Chapter 5: Standard Propagation Model

2 Standard Propagation Model

The Standard Propagation Model is a propagation model based on the Hata formulas and is suited for predictions in the
150 to 3500 MHz band over long distances (from one to 20 km). It is best suited to GSM 900/1800, UMTS, CDMA2000,
WiMAX, and LTE radio technologies.

2.1 SPM Formula

The Standard Propagation Model is based on the following formula:

 K 1 + K 2  Log  d  + K 3  Log  H Txeff  + K 4  DiffractionLoss + K 5  Log  d   Log  H Txeff  + 

P R = P Tx –  
 K 6  H Rxeff + K 7  Log  H Rx eff  + K clutter  f  clutter  + K hill LOS 

where:

• PR received power (dBm)

• P Tx transmitted power (EIRP) (dBm)
• K1 constant offset (dB)
• K2 multiplying factor for Log  d 
• d distance between the receiver and the transmitter (m)
• K3 multiplying factor for Log  H Tx 
eff

• H Tx effective height of the transmitter antenna (m)

eff

• K4 multiplying factor for diffraction calculation. K 4 must be a positive number.

• DiffractionLoss losses due to diffraction over an obstructed path (dB)
• K5 multiplying factor for Log  d   Log  H Tx 
eff

• K6 multiplying factor for H Rx

eff

• K7 multiplying factor for Log  H Rx 

eff

• H Rx effective height of the receiver antenna (i.e., mobile antenna height) (m)
eff

• K clutter multiplying factor for f  clutter 

• f  clutter  average of weighted losses due to clutter
• K hill LOS corrective factor for hilly regions (=0 in case of NLOS)

2.2 The Correspondence Between the SPM and Hata

In this section, the Hata formula on which the SPM is based is described. The correspondence between the SPM and the
Hata formula is also described.

2.2.1 Hata Formula

The SPM formula is derived from the basic Hata formula, which is:

L = A 1 + A 2 log f + A 3 log h BS +  B 1 + B 2 log h BS + B 3 h BS  log d – a  h m  – C clutter

where,

• A1 , A2 , A3 , B1 , B2 , B3 Hata parameters
• f Frequency in MHz
• h BS Effective BS antenna height in metres
• d Distance in kilometres
• a  hm  Mobile antenna height correction function
• C clutter Clutter correction function
Note: The distance in this equation is given in kilometres as opposed to the SPM, where the
distance is given in metres.

Typical values for Hata model parameters are:

• A1 = 69.55 for 900 MHz, A1 = 46.30 for 1800 MHz
• A2 = 26.16 for 900 MHz, A2 = 33.90 for 1800 MHz
• A3 = 13.82

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• B1 = 44.90
• B2 = 6.55
• B3 = 0

2.2.2 Correspondence Between Hata and SPM Parameters

In this section, the Hata and SPM parameters are compared.

2.2.2.1 Reducing the Hata and SPM Equations

Because you are only dealing with standard formulas, you can ignore the influence of diffraction and clutter correction. It
is understood that, with appropriate settings of A1 and K1, and taking only one clutter class into consideration, you can set
the clutter correction factor to zero without reducing the validity of the following equations.
The correction function for mobile antenna height can also be ignored. The mobile antenna height correction factor is zero
when hm=1.5 m, and has negligible values for realistic mobile antenna heights. The B3 parameter is usually not used and
can be considered to be 0.

The Hata formula can now be simplified to: L = A 1 + A 2 log f + A 3 log h BS +  B 1 + B 2 log h BS  log d

where:

• A1 , A2 , A3 , B1 , B2 , Hata parameters
• f Frequency in MHz
• h BS Effective BS antenna height in metres
• d Distance in kilometres
The SPM formula can be simplified to:

L = K 1 + K 2 log d + K 3 log h BS + K 5 log dlog h BS + K 6 h meff + K 7 Log  h meff 

If you rewrite the Hata equation using with the distance in metres as in the SPM formula, you get:

d
L = A 1 + A 2 log f + A 3 log h BS +  B 1 + B 2 log h BS  log -------------
1000
This leads to the following equation:

L = A 1 + A 2 log f – 3  B 1 +  A 3 – 3  B 2   log h BS + B 1 log d + B 2 log h BS  log d

2.2.2.2 Equating the Coefficients

If you compare the simplified Hata and SPM equations, you see the following correspondence between the coefficients:

K 1 = A 1 + A 2 log f – 3  B 1
K2 = B1
K3 = A3 – 3  B2
K5 = B2
K6 = 0
K7 = 0

2.2.3 Typical SPM Parameter Values

By referring to typical Hata parameters, typical SPM parameters can be determined as the following:

K 2 = 44.90
K 3 = 5.83
K 5 = – 6.55

K1 depends on the frequency, some examples are:

Project type Frequency (MHz) K1

GSM 900 935 12.5
GSM 1800 1805 22
GSM 1900 1930 23
UMTS 2110 23.8
1xRTT 1900 23

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2300 24.7
2500 25.4
WiMAX 2700 26.1
3300 27.8
3500 28.3

2.3 Making Calculations in Atoll

In this section, the different aspects of making calculations using the SPM are explained in detail:
• "Visibility and Distance Between Transmitter and Receiver" on page 15
• "Effective Transmitter Antenna Height" on page 15
• "Effective Receiver Antenna Height" on page 18
• "Correction for Hilly Regions in Case of LOS" on page 18
• "Diffraction" on page 19
• "Losses Due to Clutter" on page 19
• "Recommendations for Using Clutter with the SPM" on page 20

2.3.1 Visibility and Distance Between Transmitter and Receiver

For each calculation pixel, Atoll determines:
• The distance between the transmitter and the receiver.
- If the transmitter-receiver distance is less than the maximum user-defined distance (the break distance), the
receiver is considered to be near the transmitter. Atoll will use the set of values called “Near transmitter.”
- If the transmitter-receiver distance is greater than the maximum distance, the receiver is considered far from
the transmitter. Atoll will use the set of values called “Far from transmitter.”
• Whether the receiver is in the transmitter line of sight or not.
- If the receiver is in the transmitter line of sight, Atoll will take into account the set of values (K1, K2)LOS. The
LOS is defined by no obstruction along the direct ray between the transmitter and the receiver.
- If the receiver is not in the transmitter line of sight, Atoll will use the set of values (K1, K2)NLOS.

2.3.2 Effective Transmitter Antenna Height

The effective transmitter antenna height (HTxeff) can be calculated using one of six different methods:
• "Height Above Ground" on page 59
• "Height Above Average Profile" on page 59
• "Slope at Receiver Between 0 and Minimum Distance" on page 59
• "Spot Ht" on page 60
• "Absolute Spot Ht" on page 60
• "Enhanced Slope at Receiver" on page 60.

2.3.2.1 Height Above Ground

The transmitter antenna height is its height above the ground (HTx in metres).

H Txeff = H Tx

2.3.2.2 Height Above Average Profile

The transmitter antenna height is determined relative to an average ground height calculated along the profile between a
transmitter and a receiver. The profile length depends on the minimum distance and maximum distance values and is
limited by the transmitter and receiver locations. Distance min. and Distance max are minimum and maximum distances
from the transmitter respectively.

H Txeff = H Tx +  H 0Tx – H 0 

where,

• H 0Tx is the ground height (ground elevation) above sea level at transmitter (m).
• H 0 is the average ground height above sea level along the profile (m).
Note: If the profile is not located between the transmitter and the receiver, HTxeff equals HTx only.

2.3.2.3 Slope at Receiver Between 0 and Minimum Distance

The transmitter antenna height is calculated using the ground slope at the receiver.

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H Txeff =  H Tx + H 0Tx  – H 0Rx + K  d

where,

• H 0Rx is the ground height (ground elevation) above sea level at the receiver (m).
• K is the ground slope calculated over a user-defined distance (Distance min.). In this case, Distance min. is the
distance from the receiver.
Notes:
• If H Txeff  20m , Atoll uses 20 m in calculations.
• If H Txeff  200m , Atoll takes 200 m.

2.3.2.4 Spot Ht
If H 0Tx  H 0Rx then, H Txeff = H Tx +  H 0Tx – H 0Rx 

If H 0Tx  H 0Rx then, H Txeff = H Tx

2.3.2.5 Absolute Spot Ht

H Txeff = H Tx + H 0Tx – H 0Rx

Note: Distance min. and distance max are set to 3000 and 15000 m following ITU
recommendations (low frequency broadcast f < 500 Mhz) and to 0 and 15000 m following
Okumura recommendations (high frequency mobile telephony).

These values are only used in the last two methods and have different meanings for each method.

2.3.2.6 Enhanced Slope at Receiver

Atoll offers a new method called “Enhanced slope at receiver” to evaluate the effective transmitter antenna height.

Figure 2.1: Enhanced Slope at Receiver

The X-axis and Y-axis represent positions and heights respectively. It is assumed that the X-axis is oriented from the
transmitter (origin) towards the receiver.
This calculation is made in several steps:
1. Atoll determines line of sight between the transmitter and the receiver.
The LOS line equation is:

  H 0Tx + H Tx  –  H 0Rx + H Rx  
Los  i  =  H 0Tx + H Tx  – ------------------------------------------------------------------------------- Res  i 
d

where,

- H Rx is the receiver antenna height above the ground (m).

- i is the point index.
- Res is the profile resolution (distance between two points).
2. Atoll extracts the transmitter-receiver terrain profile.
3. Hills and mountains are already taken into account in diffraction calculations. Therefore, in order for them not to
negatively influence the regression line calculation, Atoll filters the terrain profile.

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Atoll calculates two filtered terrain profiles; one established from the transmitter and another from the receiver. It
determines the filtered height of every profile point. Profile points are evenly spaced on the basis of the profile
resolution. To determine the filtered terrain height at a point, Atoll evaluates the ground slope between two points
and compares it with a threshold set to 0.05; where three cases are possible.

Some notations defined hereafter are used in next part.

- H filt is the filtered height.

- H orig is the original height. The original terrain height is determined from extracted ground profile.

When filtering starts from the transmitter:

Let us assume that H filt – Tx  Tx  = H orig  Tx 

For each point, there are three different possibilities:

H orig  i  – H orig  i – 1 
a. If H orig  i   H orig  i – 1  and ------------------------------------------------------  0.05 ,
Res

Then, H filt – Tx  i  = H filt – Tx  i – 1  +  H orig  i  – H orig  i – 1  

H orig  i  – H orig  i – 1 
b. If H orig  i   H orig  i – 1  and ------------------------------------------------------  0.05
Res

Then, H filt – Tx  i  = H filt – Tx  i – 1 

c. If H orig  i   H orig  i – 1 

Then, H filt – Tx  i  = H filt – Tx  i – 1 

If, as well, H filt  i   H orig  i 

Then, H filt – Tx  i  = H orig  i 

When filtering starts from the receiver:

Let us assume that H filt  Rx  = H orig  Rx 

For each point, there are three different possibilities:

H orig  i  – H orig  i + 1 
a. If H orig  i   H orig  i + 1  and -------------------------------------------------------  0.05 ,
Res

Then, H filt – Rx  i  = H filt – Rx  i + 1  +  H orig  i  – H orig  i + 1  

H orig  i  – H orig  i + 1 
b. If H orig  i   H orig  i + 1  and -------------------------------------------------------  0.05
Res

Then, H filt – Rx  i  = H filt – Rx  i + 1 

c. If H orig  i   H orig  i + 1 

Then, H filt – Rx  i  = H filt – Rx  i + 1 

If, as well, H filt  i   H orig  i 

Then, H filt – Rx  i  = H orig  i 

Then, for every point of profile, Atoll compares the two filtered heights and chooses the higher one.

H filt  i  = max  H filt – Tx  i  H filt – Rx  i  

4. Atoll determines the influence area, R. It corresponds to the distance from receiver at which the original terrain
profile plus 30 metres intersects the LOS for the first time (when beginning from transmitter).
The influence area must satisfy additional conditions:

- R  3000m ,
- R  0.01  d ,
- R must contain at least three pixels.
Notes:
• When several influence areas are possible, Atoll chooses the highest one.
• If d < 3000m, R = d.

5. Atoll performs a linear regression on the filtered profile within R in order to determine a regression line.
The regression line equation is:

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y = ax + b

  d  i  – dm   Hfilt  i  – Hm 
i
a = -----------------------------------------------------------------------
-

2
 d  i  – dm 
i

and b = H m – ad m

where,

1
H m = ---
n  Hfilt  i 
i

i is the point index. Only points within R are taken into account.

R
d m = d – ----
2

d(i) is the distance between i and the transmitter (m).

Then, Atoll extends the regression line to the transmitter location. Its equation is:

regr  i  = a   i  Res  + b

6. Then, Atoll calculates the effective transmitter antenna height, H Txeff (m).

H 0Tx + H Tx – b
H Txeff = -------------------------------------
-
2
1+a

If HTxeff is less than 20 m, Atoll recalculates it with a new influence area, which begins at the transmitter.

Notes:
• If H Txeff  1000m , 1000m will be used in calculations.
• If H Txeff is less than 20 m, an additional correction is taken into account (step 7).

7. If H Txeff is less than 20 m (or negative), Atoll evaluates the path loss using H Txeff = 20m and applies a
correction factor.

Therefore, if H Txeff  20m ,

L model = L model   H Txeff = 20m  d f  + K lowant

where,

d - –  0.3   H 20   1 –  H Txeff – 20  
K lowant = --------
5 Txeff – 20   – ------------------------------------------------------------------------------
 9.63 + ------------ d   d
10 -  6.93 + -------------
 1000  1000

2.3.3 Effective Receiver Antenna Height

H Rxeff =  H Rx + H 0Rx  – H 0Tx

where,

H Rx is the height of the receiver antenna above the ground (m).

H 0Rx is the ground height (ground elevation) above sea level at the receiver (m).

H 0Tx is the ground height (ground elevation) above sea level at the transmitter (m).

Note: The calculation of effective antenna heights ( H Rxeff and H Txeff ) is based on extracted
DTM profiles. They are not performed properly if you have not imported heights (DTM file)
beforehand.

2.3.4 Correction for Hilly Regions in Case of LOS

An optional corrective term enables Atoll to correct path loss for hilly regions when the transmitter and the receiver are in
line of sight.
Therefore, if the receiver is in the transmitter line of sight and the hilly terrain correction option has been selected:

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 Chapter 5: Standard Propagation Model

L model = K 1 LOS + K 2 LOS log  d  + K 3 log  H Txeff  + K 5 log  H Txeff  log  d  + K 6  H Rx + K clutter f  clutter  + K hill LOS

When the transmitter and the receiver are not in line of sight, the path loss formula is:

L model =K 1 NLOS + K 2 NLOS log  d  + K 3 log  H Txeff  + K 4  Diffraction + K 5 log  H Txeff  log  d  + K 6  H Rx + K clutter f  clutter 
K hill LOS is determined in three steps. Influence area, R, and regression line are assumed to be available.

1. For every profile point within the influence area, Atoll calculates height deviation between the original terrain
profile and regression line. Then, it sorts points according to the deviation and draws two lines (parallel to the
regression line), one which is exceeded by 10% of the profile points and the other one by 90%.
2. Atoll evaluates the terrain roughness, h; it is the distance between the two lines.

3. Atoll calculates K hill LOS .

K hill LOS = K h + K hf

If 0  h  20m , K h = 0

2
Else K h = 7.73  log  h   – 15.29 log  h  + 6.746

If 0  h  10m , K hf = – 2  0.1924   H 0Rx + H Rx – regr  i Rx  

2 H 0Rx + H Rx – regr  i Rx 
Else K hf = – 2   – 1.616  log  h   + 14.75 log  h  – 11.21   ------------------------------------------------------------
h

iRx is the point index at receiver.

2.3.5 Diffraction
Four methods are available to calculate diffraction loss over the transmitter-receiver profile. These methods are explained
in the Technical Reference Guide.
• Deygout
• Epstein-Peterson
• Deygout with correction
• Millington
Along the transmitter-receiver profile, you can take one of the following into consideration:
• Ground altitude and clutter height (Consider heights in diffraction option). In this case, Atoll uses clutter height
information from the clutter heights file if it is available in the ATL document. Otherwise, Atoll considers average
clutter height specified for each clutter class in the clutter classes file description.
• Only ground altitude.

2.3.6 Losses Due to Clutter

Atoll calculates f(clutter) over a maximum distance from the receiver.
n

f  clutter  =  Li wi
i=1

where,
• L: loss due to clutter defined in the Clutter tab by the user (in dB).
• w: weight determined through the weighting function.
• n: number of points taken into account over the profile. Points are evenly spaced depending on the profile resolu-
tion.
Four weighting functions are available:

1
• uniform weighting function: w i = ---
n
di
• triangular weighting function: w i = -------------
n
-

 dj
j 1
• d i = D – d' i , where d’i is the distance between the receiver and the ith point and D is the maximum distance
defined.
d
log  ----i + 1
D 
• logarithmic weighting function: w i = -------------------------------------
n
-
d
log  ---- + 1

j
D 
j 1

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Measurements and Model Calibration Guide

di
----
D
e –1
• exponential weighting function: w i = --------------------------
n dj
----


D
e –1
j=1

The following chart shows the weight variation with the distance for each weighting function.

Figure 2.2: Losses due to Clutter

2.3.7 Recommendations for Using Clutter with the SPM

The decision of what clutter information you should use with the SPM depends on the type and quality of the available
information. Normally you want to use the most detailed and most accurate information. This section gives a few
recommendations on using the information available to you efficiently with the SPM. The following scenarios are possible:
• No clutter height information is available: You do not have a clutter height file and the height per clutter class
is either not defined, or is too roughly defined. In this case, you should define a loss per clutter class and not use
the height per clutter class. For more information, see "Losses per Clutter Class" on page 64.
• No clutter height file is available: You do not have a clutter height file. However, the clutter classes file has rel-
atively good data defining the height per clutter class and has a high enough resolution. In this case, you can use
the height per clutter class, but, if you use the height per clutter class, you must not define a loss per clutter class.
For more information, see "Clutter Height per Class" on page 65.
• Clutter height file is available: You have a clutter height file available that has accurate data over a resolution
that is fine enough for your network. In this case, you should use the clutter height file. But, if you use the clutter
height file, you must not use a loss per clutter class. For more information, see "Clutter Height File" on page 66.
More information is given on each option in the following sections.

Losses per Clutter Class

If you specify losses per clutter class, as illustrated in Figure 2.3:, you must not consider clutter altitudes in diffraction loss
over the transmitter-receiver profile. This approach is recommended if the clutter height information is statistical (i.e.,
where the clutter is roughly defined and without a defined altitude).
Note: Because the Standard Propagation Model is a statistical propagation model, using this
approach is recommended.

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Figure 2.3: Setting losses per clutter class

Clutter Height per Class

If you consider clutter height per class, as illustrated in Figure 2.5:, you must not define any loss per clutter class. In this
case, f(clutter) will be "0;" losses due to clutter will only be taken into account in calculated diffraction. This approach is
recommended if the clutter height information is semi-deterministic (i.e., where the clutter is roughly defined with an
average altitude per clutter class).
When the clutter height information is an average height defined for each clutter class, you must specify a receiver
clearance per clutter class. Both ground and clutter height are considered along the entire transmitter-receiver profile
except over a specific distance around the receiver (clearance), in which Atoll bases its calculations only on the DTM. The
clearance information is used to model streets because it is assumed that the receiver is in the street.

Figure 2.4: Tx-Rx profile

In Figure 2.4:, the ground altitude and clutter height (in this case, average height specified for each clutter class in the
clutter classes map description) are taken into account along the profile.

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Measurements and Model Calibration Guide

Figure 2.5: Settings when using clutter heights set per class

Clutter Height File

If you use a clutter height file, do not define any loss per clutter class, as illustrated in Figure 2.7:. In this case, f(clutter)
will be "0;" losses due to clutter will only be taken into account in calculated diffraction. This approach is recommended if
the clutter height information is deterministic (in this case, where there is a clutter height file).
It is not necessary to define receiver clearance if the height information is from a clutter height file; the clutter height
information is accurate enough to be used without additional information such as clearance. Atoll calculates the path loss
if the receiver is in the street (i.e., if the receiver height is higher than the clutter height). If the receiver height is lower than
the clutter height, the receiver is assumed to be inside a building. In this case, Atoll does not consider any diffraction for
the building (or any clearance) but takes into account the clutter class indoor loss as an additional penetration loss.
Nevertheless, Atoll does consider diffraction caused by surrounding buildings. In Figure 5.6 on page 66 this diffraction is
displayed with a green line.
Important: In order to consider indoor losses inside a building when only using a deterministic clutter
map (i.e., a clutter height map), you must clear the Indoor Coverage check box when
creating a prediction or indoor losses will be added twice (once for the entire reception
clutter class and once as indoor losses).

Figure 2.6: Diffraction caused by surrounding buildings when the receiver is indoors

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Figure 2.7: Clutter class settings when using a clutter height file

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 Chapter 4: The Model Calibration Process

4 The Model Calibration Process

This chapter explains the propagation model calibration process, from creating or selecting the project you will use to
calibrate the model, to calibrating the model, to deploying the calibrated propagation model. Two types of models can be
calibrated: SPM and Hata Models (Hokumura and Cost-Hata).
Before you can begin the calibration process, you must ensure that you have properly prepared for the process. First, the
necessary CW measurements must be available. For information on planning the CW measurement survey, see
"Collecting CW Measurement Data" on page 27.
When the CW measurement data is available, you can begin the SPM calibration process:
1. Setting up the calibration project: The first step consists of creating an Atoll document with all of the network
and geographical data necessary to recreate the CW measurement survey area. When the Atoll document has
been created with all the necessary data, you can import the CW measurement data and filter them in order to
ensure that only meaningful data is used for calibration.
- "Setting Up Your Calibration Project" on page 33.
2. Calibrate the SPM: When the CW measurement data has been selected and filtered, you can begin calibrating
the model. You must first set a few initial parameters in the propagation model and then you can begin the
calibration process, using either the automated or the assisted method. After calibration, Atoll offers several
different ways for you to analyse the calibrated propagation model.
- "Calibrating the SPM" on page 53.
3. Finalising the calibrated propagation model: When you have calibrated the propagation model and are
satisfied with the results, you must make a few final adjustments to compensate for values that could not be
calibrated due to missing or incomplete data. The missing values can be extrapolated from existing data or from
standard values.
- "Finalising the Settings of the Calibrated SPM" on page 68.
4. Deploying the calibrated propagation model: The final propagation model can now be deployed to the
transmitters for which it was calibrated.
- "Deploying the Calibrated Model" on page 70.

4.1 Setting Up Your Calibration Project

When you set up the calibration project, you must first create or select an Atoll document with the network and
geographical data necessary to recreate the CW measurement data survey area. Creating the Atoll document is
explained in "Creating an Atoll Calibration Document" on page 33. If you already have an Atoll document that you will use
to calibrate the propagation model, you can continue directly with "Importing CW Measurements" on page 34.
When you have imported the CW measurements, your next step is to verify that the CW measurement data you have just
imported correspond to the geographical data of the Atoll document you will be using for calibration. This step is very
important because Atoll will use the geographical data of the document to evaluate the CW measurement points. If the
points are not properly situated on the map, Atoll will not be able to apply the correct geographical data, especially clutter
to each point. This is explained in "Verifying the Correspondence Between Geo and Measurement Data" on page 41.
In theory, the imported measurement values are supposed to be smoothed by the measurement equipment so that they
are not subject to any fading effect. In the case the fading effects occur on the measured samples, and in order to improve
the input data for calibration, you can average them by defining a smoothing sliding window as explained in "Smoothing
Measurements to Reduce the Fading Effect" on page 76.
Once you are satisfied that the positions of the CW measurement points correspond properly to the geographical data in
the Atoll document, you can filter out the CW measurement data that, for various reasons, can not be used in the
calibration process. This is explained in "Filtering Measurement Data" on page 42.
After preparing the CW measurement data, the final step before proceeding to the calibration step is selecting the base
stations that will be used for calibration and those that will be used to verify the calibration process, as explained in
"Selecting Base Stations for Calibration and for Verification" on page 52.

4.1.1 Creating an Atoll Calibration Document

You can create the Atoll calibration document in one of two ways:
• From a template: You can create a new Atoll document from a template. Atoll is delivered with a template for
each technology you will be planning for. For information on creating a document from a template, see the User
Manual.
• From an existing document: If you already have an existing document covering the CW measurement survey
area, you can make a copy of it to use in the calibration process so that you can calibrate the propagation model
without making changes to the original document. For information on making a copy of an existing document, see
the User Manual.

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Once you have created the calibration document, you must set a few necessary parameters and import or create the
preliminary data. These steps are explained in the following sections:
• "Setting Coordinates" on page 34
• "Importing Geo Data" on page 34.

4.1.1.1 Setting Coordinates

In Atoll, you define the two coordinate systems for each Atoll document: the projection coordinate system and the display
coordinate system. By default, the same coordinate system is used for both.
The maps displayed in the workspace are referenced with the same projection system as the imported geographic data
files; thus, the projection system depends on the imported geographic file.
Note: All imported raster geographic files must be use the same cartographic system. If not, you
must convert them to a single cartographic system.

For more information on the projection and display coordinate systems in Atoll, see the User Manual.

4.1.1.2 Importing Geo Data

The geographic data is an important part of an Atoll document when the document is going to be used for a calibration
project. Several different geographic data types are used in a calibration project:
• Digital Terrain Model: The DTM describes the elevation of the ground over sea level and is indispensable in a
calibration project.
• Clutter Classes: The clutter class geo data file describes land cover or land use. Either clutter classes or clutter
heights must be present in a calibration project.
• Clutter Heights: Clutter height maps describe the altitude of clutter over the DTM with one altitude defined per
pixel. Clutter height maps can offer more precise information than defining an altitude per clutter class because,
in a clutter height file, it is possible to have different heights within a single clutter class.
Note: The only propagation models that can take clutter heights into account in calculations are
the Standard Propagation Model and WLL model.

• Vector Maps: Maps with possible survey routes defined as vectors can be imported to verify the planned survey
routes against other maps.
• Scanned Images: Scanned images are geographic data files which represent the actual physical surroundings,
for example, road maps or satellite images. They are used to provide a precise background for other objects.
Although they are not used in calculations, they can be used to verify the accuracy of proposed survey routes.
• WMS Raster-format Geo Data Files: Raster images from a Web Map Service (WMS) server. The image must
be in TIF format and be referenced in the document; it can not be embedded. You can use a WMS image to add
a precise background for other objects, or to add place names, or a map of roadways. WMS images are not used
in calculations.
For more information on any of the geographic data formats that can be used in Atoll, see the User Manual, and the
Technical Reference Guide. For information on importing geographic data, see the User Manual.

4.1.2 Importing CW Measurements

In Atoll, you can import CW measurement files in the form of ASCII text files (with tabs, semi-colons, or spaces as
separator), with DAT, TXT, and CSV extensions. For Atoll to be able to use the data in imported files, the imported files
must contain the following information:
• The position of the CW measurement points. When you import the data, you must indicate which columns give the
abscissa and ordinate (XY coordinates) of each point.
• The measured signal level at each point.
The imported files can also contain other information, such as point names and field characteristics, that can be used to
define the display of measurement points, for example, to filter points.
You can import a single CW measurement file or several CW measurement files at the same time. If you regularly import
CW measurement files of the same format, you can create an import configuration. The import configuration contains
information that defines the structure of the data in the CW measurement file. By using the import configuration, you will
not need to define the data structure each time you import a new CW measurement file.
In this section, the following are described:
• "Importing a CW Measurement Path" on page 35
• "Importing Several CW Measurement Paths" on page 36
• "Creating a CW Measurement Import Configuration" on page 37
• "Defining the Display of CW Measurements" on page 38.

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4.1.2.1 Importing a CW Measurement Path

To import a CW measurement file:
1. Click the Data tab in the Explorer window.
2. Right-click the CW Measurements folder. The context menu appears.
3. Select Import from the context menu. The Open dialogue appears.
4. Select the file or files you want to open.
5. Click Open. The Import of Measurement Files dialogue appears.
6. On the General tab:
a. Enter a Name for the CW measurement. By default, the CW measurement is given the name of the file being
imported.
b. Under Reference Transmitter, select the Transmitter with which the CW measurements were made and
select the Frequency.
c. Under Receiver, enter the Height of the receiver, the Gain, and the Losses.
d. Under Measurements, define the Unit used for the CW measurements.
e. If the Coordinates used for the CW measurement data are different than the one displayed, click the Browse
button ( ) and select the coordinate system used.
Important: CW measurements are usually made using WGS84. By default the coordinate system
displayed in the coordinates field is the display system used in the document. If the CW
measurements were made using WGS84, be sure to select WGS84, a geographic system
as indicated by the globe symbol ( ).

7. Click the Setup tab (see Figure 4.1:). If you already have an import configuration defining the data structure of the
imported file or files, you can select it from the Configuration list on the Setup tab of the Import of Measurement
Files dialogue. If you do not have an import configuration, continue with step 8.
a. Under Configuration, select an import configuration from the Configuration list.
b. Continue with step 9.

Figure 4.1: The Setup tab of the Import of Measurement Files dialogue

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Notes:
• When importing a CW measurement path file, existing configurations are available in the Files
of type list of the Open dialogue, sorted according to their date of creation. After you have
selected a file and clicked Open, Atoll automatically proposes a configuration, if it recognises the
extension. In case several configurations are associated with an extension, Atoll chooses the
first configuration in the list.
• The defined configurations are stored, by default, in the file "MeasImport.ini", located in the direc-
tory where Atoll is installed. For more information on the MeasImport.ini file, see the Adminis-
trator Manual.

8. Under File, on the Setup tab:

a. Enter the number of the 1st Measurement Row, select the data Separator, and select the Decimal Symbol
used in the file.
b. Click Setup to link file columns and internal Atoll fields. The CW Measurement Setup dialogue appears.
c. Select the columns in the imported file that give the X-Coordinates and the Y-Coordinates of each point in
the CW measurement path file.
Note: You can also identify the columns containing the XY coordinates of each point in the CW
measurement path by selecting them from the Field row of the table on the Setup tab.

d. In the Measurements box, select the field that contains the value of the measured signal for each defined
point.
e. Click OK to close the CW Measurement Setup dialogue.
f. If there is other data available in the file, in the table under File, define the Type for each additional column of
data.
9. Once you have defined the import parameters, click Import. The CW measurement data are imported into the
current Atoll document.

4.1.2.2 Importing Several CW Measurement Paths

To import several CW measurement files:
1. Click the Data tab in the Explorer window.
2. Right-click the CW Measurements folder. The context menu appears.
3. Select Import from the context menu. The Open dialogue appears.
4. Select the file or files you want to open.
Note: You can select contiguous files by clicking the first file you want to import, pressing SHIFT
and clicking the last file you want to import. You can select non-contiguous files by pressing
CTRL and clicking each file you want to import.

5. Click Open. The Import of Measurement Files dialogue appears.

6. On the General tab:
a. Enter a Name for the CW measurement. By default, the CW measurement is given the name of the file being
imported.
b. Under Reference Transmitter, select the Transmitter with which the CW measurements were made and
select the Frequency.
c. Under Receiver, enter the Height of the receiver, the Gain, and the Losses.
d. Under Measurements, define the Unit used for the CW measurements.
e. If the Coordinates used for the CW measurement data are different than the one displayed, click the Browse
button ( ) and select the coordinate system used.
Important: CW measurements are usually made using WGS84. By default the coordinate system
displayed in the coordinates field is the display system used in the document. If the CW
measurements were made using WGS84, be sure to select WGS84, a geographic system
as indicated by the globe symbol ( ).

7. Click the Setup tab (see Figure 4.1:). If you already have an import configuration defining the data structure of the
imported file or files, you can select it from the Configuration list on the Setup tab of the Import of Measurement
Files dialogue. If you do not have an import configuration, continue with step 8.
a. Under Configuration, select an import configuration from the Configuration list.
b. Continue with step 9.

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Notes:
• When importing a CW measurement path file, existing configurations are available in the Files
of type list of the Open dialogue, sorted according to their date of creation. After you have
selected a file and clicked Open, Atoll automatically proposes a configuration, if it recognises the
extension. In case several configurations are associated with an extension, Atoll chooses the
first configuration in the list.
• The defined configurations are stored, by default, in the file "MeasImport.ini", located in the direc-
tory where Atoll is installed. For more information on the MeasImport.ini file, see the Adminis-
trator Manual.

8. Under File, on the Setup tab:

a. Enter the number of the 1st Measurement Row, select the data Separator, and select the Decimal Symbol
used in the file.
b. Click Setup to link file columns and internal Atoll fields. The CW Measurement Setup dialogue appears.
c. Select the columns in the imported file that give the X-Coordinates and the Y-Coordinates of each point in
the CW measurement path file.
Note: You can also identify the columns containing the XY coordinates of each point in the CW
measurement path by selecting them from the Field row of the table on the Setup tab.

d. In the Measurements box, select the field that contains the value of the measured signal for each defined
point.
e. Click OK to close the CW Measurement Setup dialogue.
f. If there is other data available in the file, in the table under File, define the Type for each additional column of
data.
9. If you wish to save the definition of the data structure so that you can use it again, you can save it as an import
configuration:
a. On the Setup tab, under Configuration, click Save. The Configuration dialogue appears.
b. By default, Atoll saves the configuration in a special file called "MeasImport.ini" found in Atoll’s installation
folder. In case you cannot write into that folder, you can click Browse to choose a different location.
c. Enter a Configuration Name and an Extension of the files that this import configuration will describe (for
example, "*.csv").
d. Click OK.
Atoll will now select this import configuration automatically every time you import a drive test data path file
with the selected extension. If you import a file with the same structure but a different extension, you will be
able to select this import configuration from the Configuration list.

Notes:
• You do not have to complete the import procedure to save the import configuration and have it
available for future use.
• When importing a CW measurement file, you can expand the MeasImport.ini file by clicking the
button ( ) in front of the file in the Setup part to display all the available import configurations.
When selecting the appropriate configuration, the associations are automatically made in the
table at the bottom of the dialogue.
• You can delete an existing import configuration by selecting the import configuration under Setup
and clicking the Delete button.

10. Once you have defined the import parameters, you can import the selected files:
- When importing several files for the same transmitter: Click Import All. The CW measurement data are
imported into the current Atoll document.
Note: When you click the Import All button, Atoll does not import files that do match the
currently selected import configuration. It displays an error message and continues with the
next file.

- When importing several files for different transmitters:

i. Click Import. The CW measurement data are imported into the current Atoll document.
ii. Click the General tab to ensure that the information on the General tab, especially the Reference
Transmitter selected, reflect the current file being imported.
iii. If necessary, click the Setup tab and redefine the import configuration for the current file being imported.
iv. Click Import to import the current file.
v. Repeat these steps for each file being imported.

4.1.2.3 Creating a CW Measurement Import Configuration

If you regularly import CW measurement files of the same format, you can create an import configuration the first time you
import the CW measurement files. The import configuration contains information that defines the structure of the data in

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the CW measurement file. By using the import configuration, you will not need to define the data structure each time you
import a new CW measurement file.
To create a CW measurement import configuration:
1. Click the Data tab in the Explorer window.
2. Right-click the CW Measurements folder. The context menu appears.
3. Select Import from the context menu. The Open dialogue appears.
4. Select the file or files you want to open.
5. Click Open. The Import of Measurement Files dialogue appears.
6. Click the Setup tab (see Figure 4.1:).
7. Under File, on the Setup tab, define the data structure of the file or files you have selected:
a. Enter the number of the 1st Measurement Row, select the data Separator, and select the Decimal Symbol
used in the file.
b. Click Setup to link file columns and internal Atoll fields. The CW Measurement Setup dialogue appears.
c. Select the columns in the imported file that give the X-Coordinates and the Y-Coordinates of each point in
the CW measurement path file.
Note: You can also identify the columns containing the XY coordinates of each point in the CW
measurement path by selecting them from the Field row of the table on the Setup tab.

d. In the Measurements box, select the field that contains the value of the measured signal for each defined
point.
e. Click OK to close the CW Measurement Setup dialogue.
f. If there is other data available in the file, in the table under File, define the Type for each additional column of
data.
8. On the Setup tab, under Configuration, click Save. The Configuration dialogue appears.
a. By default, Atoll saves the configuration in a special file called "MeasImport.ini" found in Atoll’s installation
folder. In case you cannot write into that folder, you can click Browse to choose a different location.
b. Enter a Configuration Name and an Extension of the files that this import configuration will describe (for
example, "*.csv").
c. Click OK.
Atoll will now select this import configuration automatically every time you import a drive test data path file
with the selected extension. If you import a file with the same structure but a different extension, you will be
able to select this import configuration from the Configuration list.

Notes:
• You do not have to complete the import procedure to save the import configuration and have it
available for future use.
• When importing a CW measurement file, you can expand the MeasImport.ini file by clicking the
button ( ) in front of the file in the Setup part to display all the available import configurations.
When selecting the appropriate configuration, the associations are automatically made in the
table at the bottom of the dialogue.
• You can delete an existing import configuration by selecting the import configuration under Setup
and clicking the Delete button.
• The defined configurations are stored, by default, in the file "MeasImport.ini", located in the direc-
tory where Atoll is installed. For more information on the MeasImport.ini file, see the Adminis-
trator Manual.

4.1.2.4 Defining the Display of CW Measurements

You can define how CW measurements are displayed in Atoll’s map window. CW measurements are organised in folders
according to their reference transmitter on the Data tab of the Explorer window.
You can define the display of individual CW measurements but also set the same display parameters for all CW
measurements or for all CW measurements for the same reference transmitter.
To define the display of a CW measurement path:
1. Click the Data tab in the Explorer window.
2. Click the Expand button ( ) to expand the CW Measurements folder.
3. Click the Expand button ( ) to expand the folder of the reference transmitter.
4. Right-click the CW measurement whose display you want to define. The context menu appears.
5. Select Properties from the context menu. The Properties dialogue appears.
6. Select the Display tab. The following options are available:
- "Defining the Display Type" on page 39
- "Using the Actions Button" on page 39

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- "Defining the Visibility Scale" on page 40

- "Defining the Tip Text" on page 40
- "Adding CW Measurement Points to the Legend" on page 40.
7. Set the display parameters.
8. Click OK.

Defining the Display Type

Depending on the object selected, you can choose from the following display types: unique, discrete values, value
intervals, or advanced.
To change the display type:
1. Open the Display tab of the Properties dialogue as explained in "Defining the Display of CW Measurements" on
page 38.
To modify the appearance of the symbol:

a. Click the symbol in the table below. The Symbol Style dialogue appears.
b. Modify the symbol as desired.
c. Click OK to close the Symbol Style dialogue.
2. Select the display type from the Display Type list:
- Unique: defines the same symbol for all CW measurement points.
- Discrete values: defines the display of each CW measurement point according to the value of a selected field.
This display type can be used to distinguish CW measurement points by one characteristic. For example, you
could use this display type to distinguish CW measurement points by the clutter type they are on, or by their
reference transmitter.
i. Select the name of the Field by which you want to display the objects.
ii. You can click the Actions button to access the Actions menu. For information on the commands
available, see "Using the Actions Button" on page 39.
- Value intervals: defines the display of each object according to set ranges of the value of a selected field.
This display type can be used, for example, to distinguish population density, signal strength, or the altitude
of sites.
i. Select the name of the Field by which you want to display the objects.
ii. Define the ranges directly in the table.
iii. You can click the Actions button to access the Actions menu. For information on the commands
available, see "Using the Actions Button" on page 39.
- Advanced: allows you to display measurement points by more than one criterion at a time.
- only available for transmitters; Atoll automatically assigns a colour to each transmitter, ensuring that each
transmitter has a different colour than the transmitters surrounding it.
i. Click the symbol in the table below. The Symbol Style dialogue appears.
ii. Modify the symbol as desired.
iii. Click OK to close the Symbol Style dialogue.
iv. You can click the Actions button to access the Actions menu. For information on the commands
available, see "Using the Actions Button" on page 39.

Using the Actions Button

The Actions button on the Display tab of the Properties dialogue allows you to modify the display type as defined in
"Defining the Display Type" on page 39.
To access the Actions menu:
1. Open the Display tab of the Properties dialogue as explained in "Defining the Display of CW Measurements" on
page 38.
2. Click the Actions button. The Actions menu gives you access to the following commands:
- Select all: Atoll selects all the values in the table.
- Delete: Atoll removes selected value from the table.
- Insert before: When the selected display type is value intervals, Atoll inserts a new threshold in the table
before the threshold selected in the table.
- Insert after: When the selected display type is value intervals, Atoll inserts a new threshold in the table after
the threshold selected in the table.
- Shading: Atoll opens the Shading dialogue. When "Value Intervals" is the selected display type, you select
Shading to define the number of value intervals and configure their colour. Enter the upper and lower limits
of the value in the First Break and Last Break boxes respectively, and enter a value in the Interval box.
Define the colour shading by choosing a Start Colour and an End Colour. The value intervals will be
determined by the set values and coloured by a shade going from the set start colour to the set end colour.

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Note: Predictions and CW measurements are shaded differently. Nevertheless, you can obtain a
similar colouring by excluding the last break of the CW path display. To do this, select the
’Filter up to Last Break’ check box.

When "Discrete Values" is the selected display type, you select Shading to choose a Start Colour and an
End Colour.

Defining the Visibility Scale

You can define a visibility range for CW measurement points. A measurement point is visible only if the scale, as displayed
on the zoom toolbar, is within this range. This can be used to, for example, prevent the map from being cluttered with
symbols when you are at a certain scale.
Visibility ranges are taken into account for screen display, and for printing and previewing printing. They do not affect which
measurement points are considered during calculations.
To define the visibility range:
1. Access the Display tab of the Properties dialogue as explained in "Defining the Display of CW Measurements"
on page 38.
2. Enter a Visibility Scale minimum in the between 1: text box.
3. Enter a Visibility Scale maximum in the and 1: text box.
Note: For most object types, you can also display object information in the form of a tool tip that is
only visible when you move the pointer over the object. This option has the advantage of not
filling the map window with text. For more information on tool tips, see "Defining the Tip
Text" on page 40.

Defining the Tip Text

For most object types, such as sites and transmitters, you can display information about each object in the form of a tool
tip that is only visible when you move the pointer over the object. You can display information from every field in that object
type’s data table, including from fields that you add.
To define tip text for an object type:
1. Access the Display tab of the Properties dialogue as explained in "Defining the Display of CW Measurements"
on page 38.

2. Click the Browse button ( ) beside the Tip Text box. The Field Selection dialogue appears.
3. Select the fields which you want to display in the label:
a. To select a field to be displayed in the label for the object type, select the field in the Available Fields list and

click to move it to the Selected Fields list.

b. To remove a field from the list of Group these fields in this order, select the field in the Selected Fields list

and click to remove it.

Note: You can also display information about data objects in the form of a label that is displayed
with the object. Given the large number of CW measurement points in a CW survey,
defining labels that are always visible is not recommended.

Once you have defined the tool tips, you must activate the tool tip function before they appear.
To activate the tool tip function:

• Click the Display Tips button ( ) on the toolbar. Tool tips will now appear when the pointer is over the object.

Adding CW Measurement Points to the Legend

You can display the information defined by the display type (see "Defining the Display Type" on page 39) in your Atoll
document’s legend. Only visible objects appear in the Legend window. For information on displaying or hiding objects,
see the User Manual.
In Figure 4.2:, on the Display tab of a signal level prediction, the intervals defined are:
• Signal level >= -65red
• -65 > Signal level >= -105shading from red to blue (9 intervals)
• Signal level < -105not shown in the coverage.
The entries in the Legend column will appear in the Legend window.

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Figure 4.2: Defined thresholds as they will appear in the Legend

With value intervals, you can enter information in the Legend column to be displayed on the legend. If there is no
information entered in this column, the maximum and minimum values are displayed instead.
1. Open the Display tab of the Properties dialogue as explained in "Defining the Display of CW Measurements" on
page 38.
2. Check the Add to legend box. The defined display will appear on the legend.

4.1.3 Verifying the Correspondence Between Geo and

Measurement Data
You can quickly verify the correspondence between the CW measurements and the Atoll geo data by importing the CW
measurements and a set of vector files representing roads or a scanned map of the area and checking that the CW
measurement survey routes correspond with the geo data. You can also check whether the measurement path starts or
ends at approximately the location of the base station used for the CW measurements.
It is also important to check that the CW measurement survey routes used correspond to the planned survey routes to
ensure that the CW measurement points are evenly distributed around the station. In case measurement paths do not
exactly match the vector roads (due most of the time to inconsistencies between several coordinate systems), you can
move a set of points to the appropriate location.
To move measurement points to another location:
1. On the map, click any point to select it. To select more than one point, press CTRL as you click the other points.
To select a entire segment of points, press SHIFT as you click the other extremity of the segment.
2. Click and drag the set of points to the desired position. If you want to exactly put points on a vector line, drag them
to it until it is highlighted.
3. Release the points where you would like to place them. In the case of a vector which has to be matched, the shape
of the paths might be modified accordingly after the points have been released.
If the IDs of the CW measurement points do not reflect the order in which the measurements were collected, you can check
whether the station location is consistent with its relative measurement path by displaying measurement points according
to measurement levels, as shown in Figure 4.3:. For information on setting the display according to measurement levels,
see "About Potentially Invalid Measurement Levels" on page 48.

Figure 4.3: Distribution of the Measured Signal Strength around a station

If panoramic photographs of the area surrounding the base station are available, you should verify that there are no nearby
obstacles disturbing propagation. If there is an obstacle close to the base station, you can filter out the obstructed CW

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measurement data using an angle filter or remove the station from the set of CW measurement data if the obstruction is
too wide. For information on defining an angle filter, see "Filtering by Angle" on page 51.

4.1.4 Filtering Measurement Data

One of the most important steps in preparing CW measurement data for use in a calibration project is filtering the
measurement points. When you are filtering CW measurement data, the goal is to eliminate the points that are the least
representative of the survey area while retaining a number of points that is both representative and large enough to provide
statistically valid results.
The filtering process is often, therefore, a series of trade-offs. Although you would normally consider filtering out certain
data if, for example, their values appear high or low, if filtering them all out leaves you with too small a sample, you might
consider leaving some of them in. By the same token, if filtering out the points on a clutter class means that that clutter
class will no longer be represented at all, you might consider leaving those points on the CW survey path where they are
best represented.
There are several reasons why you would not want to take certain measurement points into consideration:
• The measurement points might appear potentially invalid, they might be in clutter classes that are of no signifi-
cance in terms of the propagation model to be calibrated, they may show extreme signal levels, they might be too
close to the transmitter, or they might suffer from too much diffraction.
• The zones where the measurement points are located might be in an area where the results can not be considered
accurate (for example, any points coming from behind a directional antenna should not be used in a calibration
project).
If you wish, you can permanently delete the points you filter out. You can always re-import the original measurement data
if you want to add those points again. Or you can filter them out for the current calibration, but leave them in the
measurement data.
Filtering CW measurement data is made in several steps. Depending on the CW measurement data available and the
individual calibration project, it is possible that not all steps will be necessary, however, the basic steps are:
1. Filtering by clutter class: The first step in filtering CW measurement data is to filter out points by clutter class.
Typically you will want to remove all points on clutter classes that are represented by less than 5% of the total
measurement points in the CW survey. For information on filtering by clutter class, see "Filtering on Clutter
Classes" on page 42.
2. Filtering by signal strength and distance: The next step is to filter out points that lay outside of a defined range
of signals and that are either too close to or too far from the reference transmitter. For information on filtering by
distance and signal strength, see "Signal and Distance Filtering" on page 44.
3. Removing sections that are not representative: The final step in filtering CW measurement data consists of
examining the CW measurement data to remove points that are affected by obstruction or that are potentially
invalid, i.e., measurement points affected by diffraction or measurement points that are too high or too low. For
information on filtering by distance and signal strength, see "Filtering by Geo Data Conditions" on page 47.
Important: If you set filters on the CW Measurements folder, any filters set on individual CW
measurement paths will be erased.

4.1.4.1 Filtering on Clutter Classes

The first step in filtering measurement points is to filter out the points by clutter class. If only a few measurement paths
have points on a given clutter class or only a few points are located on this class, then the clutter class should be filtered
out. There are not enough points to give a statistically good sampling of the conditions for that clutter class. In other words,
keeping these points will likely cause the clutter class to be incorrectly calibrated, leading to incorrect coverage prediction
results when the calibrated propagation model is used. Therefore, it is highly recommended not to take irrelevant clutter
classes into account during the calibration process, and to deduce the clutter losses afterwards using similar clutter
classes and typical values.
The rule of thumb is 5%: if only 5% of the points on a measurement plan are on a given clutter class, the points for that
clutter class should be removed. However, this should just be used as a guideline. Under certain circumstances, for
example, if that clutter class is not well represented in any survey path, you might want to keep them. You can always try
calibrating the propagation model once with the clutter class and once without and comparing the results.
You should also remove the measurement points located on clutter classes that are not at all representative of the survey
area. For example, there may be a park along the survey route that is classified as "Forest" in terms of clutter class. If the
area itself is mostly dense urban, keeping the points in the forest clutter class will lead to inaccurate results.
You can view the point distribution statistics for all CW measurements, or all CW measurements for a single reference
transmitter, or for a single CW measurement path. Figure 4.4: shows the distribution of statistics for all CW measurements.
Important: Before the point distribution statistics can be displayed, you must calculate signal levels on
the CW measurement points. You can calculate signal levels by right-clicking the CW
Measurements folder and selecting Calculations > Calculate Signal Levels from the
context menu.

To display the point distribution statistics for CW measurements:

1. On the Data tab of the Explorer window, right-click the CW measurements whose statistics you wish to display:
- All CW measurements: Right-click the CW Measurements folder.

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- All CW measurements for a single reference transmitter: Click the Expand button ( ) to expand the CW
Measurements folder and right-click the folder of the reference transmitter.
- A single CW measurement path: Click the Expand button ( ) to expand the CW Measurements folder and
click the Expand button ( ) to expand the folder of the reference transmitter. Then, right-click the CW
measurement path.
The context menu appears.

2. Select Display Statistics from the context menu.

If more than one CW measurement path is selected, a dialogue appears where you can choose the statistics of
which CW measurement paths you want to display. Select or clear the check boxes to choose the CW
measurement paths and click OK.

The statistics dialogue appears, with the distribution of the selected CW measurements (see Figure 4.4:).

3. Take note of the clutter classes that have few measurement points (with only 5% or lower of the total number of
points).
4. Click Close to close the dialogue.

Figure 4.4: Point distribution in the different clutter classes

To filter out the measurement points from the under-represented clutter classes:
1. On the Data tab of the Explorer window, right-click the CW measurements whose statistics you have just
examined:
- All CW measurements: Right-click the CW Measurements folder.
- All CW measurements for a single reference transmitter: Click the Expand button ( ) to expand the CW
Measurements folder and right-click the folder of the reference transmitter.
The context menu appears.

2. Select Filter from the context menu. The CW Measurement Filter dialogue appears.
3. In the Per Clutter window, under Filter, clear the check boxes of the clutter classes you want to filter out. Only the
clutter classes whose check box is selected will be taken into account.
4. If you want to keep the measurement points inside the focus zone, select the Use focus zone to filter check box.
5. If you want to permanently remove the measurement points outside the filter, select the Delete Points Outside
Filter check box.
Warning: Remember that, by selecting the Delete Points Outside Filter check box, you are defining
a property of the CW measurement path. Once you have defined this property, points that
you filter out using other methods, for example, using the Filtering Assistant (see "Using
the Filtering Assistant on CW Measurement Points" on page 45) will also be permanently
deleted.

If you permanently delete measurement points and later want to use them, you will have to re-import the original
measurement data.

6. Click OK. The selected CW measurement data will be filtered according to the defined parameters.
The filter settings can also be saved to a filter configuration which can be retrieved afterward.
You can also filter out the measurement points from the under-represented clutter classes on a single CW measurement
path by using the Filtering assistant (see "Using the Filtering Assistant on CW Measurement Points" on page 45).

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See "Displaying Statistics Over a Measurement Path" on page 78 and "Displaying Statistics Over Several Measurement
Paths" on page 78 for more information on measurement path statistics.
Note: The Clear All button resets the existing filters.

4.1.4.2 Signal and Distance Filtering

The goal of the calibration process is to produce an accurate propagation model which can be used to reliably calculate
the propagation of each base station within the area. To respect this goal, the propagation model’s own constraints with
respect to signal levels have to be taken into account. There are limitations in the measurement equipment, which also
have to be considered.
In this section, filtering out CW measurement points based on the signal strength or their distance from the reference
transmitter is explained:
• "Typical Values" on page 44
• "Using Manual Filtering on CW Points" on page 44
• "Creating an Advanced Filter" on page 45
• "Using the Filtering Assistant on CW Measurement Points" on page 45.

4.1.4.2.1 Typical Values

The values to be used to filter CW measurements depend on a lot of factors. In this section, some typical values are given.
These values are by definition general. Atoll provides a filtering assistant that can be used for each CW measurement
path; it is highly recommended to use the filtering assistant to define a specific signal and distance filters for each CW
measurement file. For information on the filtering assistant, see "Using the Filtering Assistant on CW Measurement Points"
on page 45.
When filtering out CW measurement points by signal strength, generally, signal levels above -40 dBm are filtered out,
because they would be inaccurate because of receiver overload. When you filter on the minimum signal level, the
sensitivity of the receiver and tolerance have to be considered. Therefore, signals below “Receiver Sensitivity + Target
Standard Deviation” have to be filtered out to avoid the effect of noise saturation in the results. A typical value for the
minimum signal level filter can be then considered to be:
-120 + 8 = -112 dBm

When filtering out by distance from the reference transmitter, measurement data at a distance of less than 200 m from the
station should be discarded because these points are too close to the station to properly represent the propagation over
the whole area. A typical maximum value is 10 km for rural areas.

4.1.4.2.2 Using Manual Filtering on CW Points

When you filter CW measurements on signal strength or distance, you can filter the values in either all CW measurement
paths, in all the CW measurement paths for one reference transmitter, or in a single CW measurement path.
To filter out CW measurement points on signal strength or distance:
1. On the Data tab of the Explorer window, right-click the CW measurements whose points you want to filter:
- All CW measurements: Right-click the CW Measurements folder.
- All CW measurements for a single reference transmitter: Click the Expand button ( ) to expand the CW
Measurements folder and right-click the folder of the reference transmitter.
The context menu appears.

2. Select Filter from the context menu. The CW Measurement Filter dialogue appears.
3. Under Filter, define the settings for signal strength and distance:
- Distance between CW measurement point and reference transmitter: Enter the Min. Distance and Max.
Distance. Atoll will keep only CW measurement points which are within this range.
- Measured signal: Enter the Min. Measurement and Max. Measurement. Atoll will keep only CW
measurement points whose value is within this range.
You can also use this dialogue to filter on the following criteria:

- Clutter class: For information on filtering by clutter class, see "Filtering on Clutter Classes" on page 42.
- Angle with the antenna azimuth: For information on filtering by the angle with the antenna azimuth, see
"Filtering by Angle" on page 51.
- Additional fields: For information on filtering with additional fields, see "Creating an Advanced Filter" on
page 45.
4. If you want to keep the measurement points inside the focus zone, select the Use focus zone to filter check box.
5. If you want to permanently remove the measurement points outside the filter, select the Delete Points Outside
Filter check box.
Caution: If you permanently delete measurement points and later want to use them, you will have to
re-import the original measurement data.

6. Click OK. The selected CW measurement data will be filtered according to the defined parameters.
The filter settings can also be saved to a filter configuration which can be retrieved afterward.

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You can also filter out CW measurement points on signal strength or distance on a single CW measurement path by using
the Filtering assistant (see "Using the Filtering Assistant on CW Measurement Points" on page 45).
Note: The Clear All button resets the existing filters.

4.1.4.2.3 Creating an Advanced Filter

Atoll enables you to create an advanced filter using several fields and expressions with which you can filter CW
measurement points. You can create an advanced filter to filter the values in either all CW measurement paths, in all the
CW measurement paths for one reference transmitter, or in a single CW measurement path.
To filter out CW measurement points using an advanced filter:
1. On the Data tab of the Explorer window, right-click the CW measurements whose points you want to filter:
- All CW measurements: Right-click the CW Measurements folder.
- All CW measurements for a single reference transmitter: Click the Expand button ( ) to expand the CW
Measurements folder and right-click the folder of the reference transmitter.
The context menu appears.

2. Select Filter from the context menu. The CW Measurement Filter dialogue appears.
3. Click the More button. The Filter dialogue appears.
4. In the Column row, select the name of the column to be filtered on from the list. Select as many columns as you
want.
5. Underneath each column name, enter the criteria on which the column will be filtered as explained in the following
table:

Formula Data are kept in the table only if

=X value equal to X (X may be a number or characters)

<> X value not equal to X (X may be a number or characters)

<X numerical value is less than X

>X numerical value is greater than X

<=X numerical value is less than or equal to X

>=X numerical value is greater than or equal to X

*X* text objects which contain X

*X text objects which end with X

X* text objects which start with X

6. Click OK to filter the data according to the criteria you have defined.
Filters are combined first horizontally, then vertically.
The filter settings can also be saved to a filter configuration which can be retrieved afterward.
You can also filter out CW measurement points using an advanced filter on a single CW measurement path by using the
Filtering assistant (see "Using the Filtering Assistant on CW Measurement Points" on page 45).
Note: The Clear All button resets the existing filters.

4.1.4.2.4 Using the Filtering Assistant on CW Measurement Points

Atoll makes available a Filtering Assistant to help you filter the CW measurements points of each CW measurement
path. Because each CW measurement path is made under different circumstances, you can only use the Filtering
Assistant on individual CW measurement paths, and not on groups of CW measurement paths, even if they are for the
same reference transmitter.
Nevertheless, if you can provide several measurement paths for a same transmitter and want to use the filtering assistant
for all of them, you can merge all or part of these in a unique table. See "Merging Measurement Paths for a Same
Transmitter" on page 76.
To use the Filtering Assistant:
1. On the Data tab of the Explorer window, click the Expand button ( ) to expand the CW Measurements folder.
The CW Measurements folder opens.
2. Click the Expand button ( ) to expand the folder of the reference transmitter. The reference transmitter folder
opens.
3. Right-click the CW measurement path. The context menu appears (see Figure 4.5:).

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Figure 4.5: Filtering Assistant Launching

4. Select Filtering Assistant from the context menu. The Filtering Assistant dialogue appears (see Figure 4.6:).
The Filtering Assistant dialogue displays measurements by 10log(d), where "d" represents the distance. This
enables you to check whether measurement points are homogeneously distributed for the relevant signal level
and distance according to a linear function.

The Filtering Assistant enables you to filter by entering the values for Min. Distance, Max Distance, Min.
Measurement, and Max Measurement. Or, you can filter by drawing a rectangle in the graph. You can select the
points to keep or you can select areas with few points to exclude the points. After including or excluding points,
you can verify the number of points remaining and their percentage of the whole.
5. Under Clutter, clear the check box of any clutter class that is either under-represented or unrepresentative of the
survey zone. For more information, see "Filtering on Clutter Classes" on page 42.
6. Filter the measurement points by selection. Typically, you will first select the points to include, respecting minimum
distance and minimum and maximum values, and then you will exclude the anomalous points from that selection.
To select points to include:

a. Click on the graph where you want to start the rectangle that will contain the points to keep.
b. Drag to the opposite corner. The selection rectangle appears outlined in red.
When you release the mouse, the values reflected by the current selection are displayed in the fields on the
left.
c. Right-click the rectangle. The context menu appears.
d. Select Filter Selected Points from the context menu (see Figure 4.6:). All points outside the rectangle are
filtered out.
The Number of Points field displays the number of points kept as well as their percentage of the whole.

Figure 4.6: Point Selection Tool in the Filtering Assistant

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To select points to exclude:

a. Click on the graph where you want to start the rectangle that will contain the points to exclude.
b. Drag to the opposite corner. The selection rectangle appears outlined in red.
When you release the mouse, the values reflected by the current selection are displayed in the fields on the
left.

c. Right-click the rectangle. The context menu appears.

Figure 4.7: Point Exclusion Tool in the Filtering Assistant

d. Select Excluded Selected Points from the context menu (see Figure 4.7:). All points inside the rectangle are
filtered out.
The Number of Points field displays the number of points kept as well as their percentage of the whole.
7. Click OK to apply the filters and close the dialogue.
Notes:
• When moving the mouse over the graph, the related distance, measurement, and point index
are displayed in the left of the dialogue.
• The Clear All button resets the existing filters.

4.1.4.3 Filtering by Geo Data Conditions

After you have made an initial selection of CW measurement points based on clutter classes and signal strength and
distance, you can filter points based on geo data conditions.
There are several reasons why you should remove certain CW measurement points from a CW measurement path:
• Areas that suffer from diffraction: Areas that suffer from a large amount of diffraction should be filtered out
because they are not representative of the entire area. For more information, see "About Diffraction" on page 47.
• Sections that are not representative of the survey area: Certain measurement points may not be representa-
tive of the entire area. For more information, see "About Specific Sections" on page 48.
• Areas around the reference transmitter where obstacles prevent proper propagation: Some measurement
points should be removed because their reception is affected by obstructions between the measurement point and
the reference transmitter. As well, measurement points that are behind a non-omni-directional antenna should be
removed. For more information, see "About Specific Sections" on page 48.
• Areas with potentially invalid points: Measurement points with a signal level that is significantly higher or lower
than the CW measurement points around them should be removed, as they could be invalid. For more information,
see "About Potentially Invalid Measurement Levels" on page 48.
You can select and remove CW measurement points in several ways:
• You can delete CW measurement points from the data table: "Deleting a Selection of Measurement Points"
on page 50
• You can draw a filtering zone: "Using Filtering Zones on CW Measurement Points" on page 51
• You can filter out the points by their angle with the reference transmitter: "Filtering by Angle" on page 51.

4.1.4.3.1 About Diffraction

CW measurement points that suffer from a large amount of diffraction should be filtered out because they are not
representative of the entire area. For example, if there are three diffraction peaks in the profile between the station and
the measurement points there’s a greater chance of errors and thereby a negative influence on calibration.
You can use the CW Measurement Analysis Tool and the Point Analysis Tool to quickly review each measurement
path for measurement points that have too many diffraction points. The profile between the site and the CW measurement
point is displayed in the Point Analysis Tool window (see Figure 4.8:).

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Figure 4.8: Point Analysis Tool window showing diffraction peaks

For more information on using the CW Measurement Analysis Tool and the Point Analysis Tool to display diffraction
peaks, see "Using the CW Measurement and the Point Analysis Tools" on page 66.

4.1.4.3.2 About Specific Sections

Under certain conditions, certain sections of CW survey routes must be removed before calibration. The values of the CW
measurements in these sections could have been influenced by conditions in the profile between the measurement point
and the reference transmitter. For example:
• A section where the profile between the transmitter and the receiver includes a forest area (unless this configura-
tion is representative of the survey area)
• A section where the profile between the transmitter and the receiver passes over water (unless this configuration
is representative of the survey area)
• A section of measurement points on a bridge
• A section of measurement points in a tunnel
• A section where the profile between the transmitter and the receiver is obstructed near the transmitter
• A section of CW measurement points behind an antenna that is not omni-directional.
These points can be selected and deleted or filtered out by:
• Selecting them in the data table: For information, see "Deleting a Selection of Measurement Points" on page 50
• Creating an exclusion zone: For information, see "Using Filtering Zones on CW Measurement Points" on page 51
• Filtering them out by their angle to the antenna: For information, see "Filtering by Angle" on page 51.

4.1.4.3.3 About Potentially Invalid Measurement Levels

Some CW measurement points might have a signal level that is significantly higher or lower than the CW measurement
points around them. These points should be removed as they could be invalid and would, therefore, have a negative effect
on the accuracy of the calibration project.
Atoll enables you to verify the signal level of the CW measurement points:
• "Displaying CW Measurement Points by Signal Level" on page 48
• "Using the CW Measurement Analysis Tool" on page 49.
Once you have verified the signal level, potentially invalid measurements can be selected and deleted or filtered out by:
• Selecting them in the data table: For information, see "Deleting a Selection of Measurement Points" on page 50
• Creating an exclusion zone: For information, see "Using Filtering Zones on CW Measurement Points" on
page 51
• Filtering them out by their angle to the antenna: For information, see "Filtering by Angle" on page 51.

Displaying CW Measurement Points by Signal Level

You can check whether propagation is homogeneous for all measurement paths by displaying each CW measurement
point on a single path by signal level and displaying a grid around the reference transmitter (see Figure 4.9:). This way you
can check on the map whether the propagation loss is spatially homogeneous. Any sudden drop in signal level or any
areas where the received signal does not match your expectations will be immediately visible.

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Figure 4.9: Distribution of the point positions around a station

To display the signal level of CW measurement points on the map:

1. Click the Data tab of the Explorer window.
2. In the CW Measurements folder, clear the display check box beside all CW measurement paths except the one
you want to display.
This will limit the number of points displayed to the ones you want to examine.

3. Define the display settings of the CW measurement path:

a. Select the Display tab.
b. Set the Display Type and select signal strength from the Field list. For more information, see "Defining the
Display Type" on page 39.
4. Add the CW measurement points to the legend, as explained in "Adding CW Measurement Points to the Legend"
on page 40.
5. Select View > Legend Window. The Legend window appears.
6. Define the grid around the reference transmitter:
a. Right-click the reference transmitter in the map window. The context menu appears.
b. Select Grid from the context menu. The Radial Grid dialogue appears.
c. Define a radial grid around the reference transmitter that covers the survey area.
d. Click OK.
By examining the displayed CW measurement points on the map, you can see on the map whether the
propagation loss is spatially homogeneous.

Using the CW Measurement Analysis Tool

You can use the CW Measurement Analysis Tool to analyse variations in the signal level on all points on the CW
measurement path. The CW Measurement Analysis Tool indicates any sudden drop in signal level or any areas where
the received signal does not match your expectations.
To analyse data variations using the CW Measurement Analysis Tool window.
1. Click the Data tab in the Explorer window.
2. Click the Expand button ( ) to expand the CW Measurements folder.
3. Click the Expand button ( ) to expand the folder with the CW measurement path you want to analyse.
4. Right-click the CW measurement path. The context menu appears.

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5. Select Open the Analysis Tool from the context menu. The CW Measurement Analysis Tool window appears
(see Figure 4.10:)

Figure 4.10: The CW Measurement Analysis Tool window

6. You can display the data in the CW measurement path in two ways:
- Click the values in the CW Measurement Analysis Tool window.
- Click the points on the CW measurement path in the map window.
The CW measurement path appears in the map window as a line connecting the reference transmitter and the CW

measurement point, which is indicated by the pointer ( ).

7. You can display a second Y-axis on the right side of the window in order to display the values of a second variable.
You can select the secondary Y-axis from the list on the right-hand side on the top of the CW Measurement
Analysis Tool window.
8. You can change the zoom level of the CW Measurement Analysis Tool window in the following ways:
- Zoom in or out:
i. Right-click the CW Measurement Analysis Tool window.
ii. Select Zoom In or Zoom Out from the context menu.
- Select the data to zoom in on:
i. Right-click the CW Measurement Analysis Tool window on one end of the range of data you want to
zoom in on.
ii. Select First Zoom Point from the context menu.
iii. Right-click the CW Measurement Analysis Tool window on the other end of the range of data you want
to zoom in on.
iv. Select Last Zoom Point from the context menu. The CW Measurement Analysis Tool window zooms
in on the data between the first zoom point and the last zoom point.
9. Click the data in the CW Measurement Analysis Tool window to display the selected point in the map window.
Atoll will recentre the map window on the selected point if it is not presently visible.

Tip: If you open the table for the CW measurement path you are displaying in the CW
Measurement Analysis Tool window, Atoll will automatically display in the table the data for the point
that is displayed in the map and in the CW Measurement Analysis Tool window.

4.1.4.3.4 Deleting a Selection of Measurement Points

When you have identified unreliable or irrelevant sections, you can remove them by deleting them from the data table.
To delete measurement points from the data table:
1. Click the Data tab of the Explorer window.
2. In the CW Measurements folder, right-click the CW measurement path with the points you want to delete. The
context menu appears.
3. Select Open Table from the context menu. The data table appears.
4. Right-click the column name for the Id column. The context menu appears.
5. Select Sort Ascending or Sort Descending from the context menu. The contents of the data table are sorted by
the Id of the CW measurement point.
Because the CW measurement points on the map are ordered sequentially by their Id, ordering the contents of
the data table by Id makes it easier to select and delete contiguous selections of CW measurement points.

6. In the data table, click the first point of the sequence to be deleted, press SHIFT and click the last point of the
sequence.

Tip: When you select a CW measurement point on the map, Atoll automatically selects the
same point in the data table. So, by arranging the map window and the data table so that both are
visible, you can locate the first and last points of the selection in the data table by clicking them on the
map.

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7. Press DEL to delete the CW measurement points permanently from the data table.
Caution: If you permanently delete measurement points and later want to use them, you will have to
re-import the original measurement data.

Figure 4.11: Simultaneous display of measurement path and table

4.1.4.3.5 Using Filtering Zones on CW Measurement Points

When you have identified unreliable or irrelevant sections on a CW measurement path, you can filter them out by creating
a filtering zone over the points you want to exclude. A filtering zone applies only to the CW measurement path on which it
is made. This filter is added to any other filters applied to the CW measurement path.
To define a filtering zone on measurement points:
1. Click the Data tab in the Explorer window.
2. Click the Expand button ( ) to expand the CW Measurements folder.
3. Click the Expand button ( ) to expand the folder of the reference transmitter.
4. Right-click the CW measurement from which you want to exclude some points with a filtering zone. The context
menu appears.
5. Select Filtering Zones > Draw from the context menu. The Properties dialogue appears.
6. Draw the filtering zone to cover:
a. Click once on the map to start drawing the zone.
b. Click once on the map to define each point on the map where the border of the zone changes direction.
c. Click twice to finish drawing and close the zone.
The filtering zone is delimited by a red line. The points of the path inside the filtering zone are filtered out of the display
and the data table. They are not taken into consideration in any calculations.
You can create several filtering polygons for each path.
Note: When you have created several filtering polygons for a path, you can delete all of them at
the same time by selecting the Delete Filtering Polygons check box in the CW
Measurement filter dialogues.

4.1.4.3.6 Filtering by Angle

When you have sections of the CW measurement path that are obstructed by obstacles in the profile close to the
transmitter between the CW measurement point and the reference transmitter or when the antenna is not completely omni-

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directional, you can filter out CW measurement points that are outside of a set angle from the reference transmitter
antenna beam.
To define a filter by angle:
1. On the Data tab of the Explorer window, right-click the CW measurements whose points you want to filter by
angle:
- All CW measurements: Right-click the CW Measurements folder.
- All CW measurements for a single reference transmitter: Click the Expand button ( ) to expand the CW
Measurements folder and right-click the folder of the reference transmitter.
The context menu appears.

2. Select Filter from the context menu. The CW Measurement Filter dialogue appears.
3. Under Azimuth/Point Angle, select one of the following:
- Relative: Select Relative if the antenna is directional. The entered angles will then be offset from the
antenna’s azimuth.
- Absolute: Select Absolute if the antenna is omnidirectional. Because an omnidirectional antenna has no
azimuth, the entered angles will then be offset from the north.
4. Define the negative and positive angles of the aperture:
a. Min. Angle: Enter a minimum angle from 0 to -180 degrees.
b. Max. Angle: Enter a minimum angle from 0 to 180 degrees.
In the example in Figure 4.12:, a filter from -140 to 140 degrees relative to the antenna azimuth has been created
to filter out CW measurement points in the 80 degrees directly behind the antenna.

Figure 4.12: Angular Filter around a station

5. If you want to keep the measurement points inside the focus zone, select the Use focus zone to filter check box.
6. If you want to permanently remove the measurement points outside the filter, select the Delete Points Outside
Filter check box.
Caution: If you permanently delete measurement points and later want to use them, you will have to
re-import the original measurement data.

7. Click OK.
The filter settings can also be saved to a filter configuration which can be retrieved afterward.
You can also filter out CW measurement points using a filter by angle on a single CW measurement path by using the
Filtering assistant (see "Using the Filtering Assistant on CW Measurement Points" on page 45).

4.1.5 Selecting Base Stations for Calibration and for Verification

Once you have imported and filtered the CW measurement data, you can select the base stations that you will use for
calibration and those you will use for verification. Selecting the correct base stations for calibration and verification is an
important step in the process of calibrating the propagation model.
In "Selecting Base Stations" on page 28, it is recommended to have at least eight base stations. With a total of eight base
stations, two base stations will be required for verification.

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If not enough base stations are available (in other words, if there are less than eight base stations per propagation model
being calibrated), you should use all the base stations for calibration. You can verify the calibration later by using the same
measurement paths as in the calibration process.
When selecting base stations for calibration and for verification, you should keep the following guidelines in mind:
• For calibration: Select paths that cover the entire area so that all the area characteristics can be taken into
account during the calibration process.
• For verification: Select several paths (the number depends on the total number of available paths) that are within
the covered area and not at the outer boundaries. Ensure that the areas covered by the verification paths are also
covered by the calibration paths.

4.2 Calibrating the SPM

When the CW measurement data have been imported into the Atoll calibration project and prepared as explained in
"Setting Up Your Calibration Project" on page 33, you can calibrate the SPM. Atoll offers both an automatic and an
assisted calibration wizard.

4.2.1 Quality Targets

The quality of the final calibrated propagation model depends strongly on the quality of the CW measurements used in the
calibration process. Therefore, you will only be able to meet the following quality targets if the CW measurements used in
the calibration process are of good quality, the provided radio data are correct, and the described calibration procedure is
followed.
Calibration Sites:
• Global mean error on calibration sites: < 1 dB
• Global standard deviation on calibration sites: < 8 dB
• Mean error on each calibration site: < 2.5 dB
• Standard deviation on each calibration site: < 8.5 dB
Verification Sites:
• Global mean error on verification sites: < 2 dB
• Global standard deviation on verification sites: < 8.5 dB

4.2.2 Setting Initial Parameters in the SPM

Before starting the calibration process, you have to set a few parameters in the SPM.

Tip: After you have set initial parameters, you can retain the original copy of the SPM by
creating a copy of the SPM and calibrating the copy instead. This allows you to restart calibration from
the original version if you should need to. You can create a copy of the SPM by right-clicking the SPM
on the Modules tab of the Explorer window and selecting Duplicate from the context menu.

In this section, the following initial SPM parameters are explained:

• "Parameters Tab" on page 53
• "Clutter Tab" on page 55.

4.2.2.1 Parameters Tab

To set or verify settings on the Parameters tab of the SPM’s Properties dialogue:
1. Click the Modules tab in the Explorer window.
2. Click the Expand button ( ) to expand the Propagation Modules folder.
3. Right-click the copy of the SPM that you want to calibrate. The context menu appears.
4. Select Properties from the context menu. The Properties dialogue appears.
5. Click the Parameters tab (see Figure 4.13:).

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Figure 4.13: SPM Transmitter effective height method selection

6. Verify the following settings on the Parameters tab:

Near Transmitter:
- Maximum Distance (m): Under Near Transmitter, ensure that Maximum Distance (m) is set to "0." If this
parameter is not set to "0," it will be forced to "0" during the automatic calibration process because the
algorithm can not calibrate a dual-slope model.
Effective Antenna Height:

- Method: The Method you choose depends on the relief of the survey area to be used in calibration. The
automatic calibration process adapts antenna height (as set in the transmitter properties) during calculations
according to the characteristics of the profile between the transmitter and the receiver. You can either set the
method yourself now, or it can be set automatically during the automatic calibration process.
Diffraction:

- Method: You can select the method use to calculate diffraction. The Millington method can only calculate one
diffraction edge. All other diffraction methods can calculate three diffraction edges.
Other Parameters:

- Hilly Terrain Correction: The correction for hilly terrain correction cannot be modified by the automatic
calibration process and therefore you must set it beforehand. If you decide to manually adjust these
parameters, the following configurations are recommended:
For hilly terrain:

- Effective Antenna Height: Under Effective Antenna Height, select "5 - Enhanced slope at receiver" as
the Method.
- Hilly Terrain Correction: Under Other Parameters select "1 - Yes" to activate the Hilly Terrain
Correction.
For flat terrain:

- Effective Antenna Height: Under Effective Antenna Height, select "1 - Height above average profile"
as the Method.
- Hilly Terrain Correction: Under Other Parameters select "0 - No" to deactivate the Hilly Terrain
Correction.
- Kclutter: Ensure that Kclutter is set to "1." Kclutter is the multiplicative factor of loss if the losses defined per
clutter class are used inn the SPM formula.
- Limitation to Free Space Loss: Select "1 - Yes" to activate Limitation to Free Space Loss. Activating
Limitation to Free Space Loss ensures that unrealistic values are not taken into account during the
automatic calibration process.
- Profiles: Select "0 - Radial" from Profiles. Activating radial optimisation ensures that profile extraction is
precise enough for the purposes of calibration while ensuring that calculation time is significantly improved.
- K6: Ensure that K6 is set to "0." Because the K6 coefficient is a direct multiplicative factor of the receiver height
in the formula used to calculate path loss, it can influence propagation results in an unrealistic way.

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- K7: The K7 coefficient has little influence on the performance propagation model and can usually be set to "0."
It is a direct multiplicative factor of the log of the receiver height in the formula used to calculate path loss; an
incorrect setting can influence propagation results in an unrealistic way.
Other Ki values will be calibrated during the automatic calibration process.

4.2.2.2 Clutter Tab

To set or verify settings on the Clutter tab of the SPM’s Properties dialogue:
1. Click the Modules tab in the Explorer window.
2. Click the Expand button ( ) to expand the Propagation Modules folder.
3. Right-click the copy of the SPM that you want to calibrate. The context menu appears.
4. Select Properties from the context menu. The Properties dialogue appears.
5. Click the Clutter tab (see Figure 4.14:).
6. Verify the following settings on the Clutter tab (for more information on the settings available on the Clutter tab,
see "Recommendations for Using Clutter with the SPM" on page 20):
Clutter Taken into Account, you can set the following parameters under Heights:

- Clutter Taken into Account in Diffraction: Given the impact that clutter heights have when calculating loss
by diffraction, this method should only be used when the height information available is very precise.
If clutter height files or high resolution (5m) clutter class files are available, select "1 - Yes" to have clutter taken
into account in diffraction. If you select "1 - Yes", you must set Kclutter to "0" on the Parameters tab of the
Properties dialogue, to ensure that the calibration will not calculate clutter losses.

If there is no clutter heights file available and the clutter class files are low resolution, select "0 - No" to not
have clutter taken into account when calculating diffraction. The effect of clutter on propagation will be taken
into account using clutter losses, which will be calculated during the calibration process. The calculated clutter
losses can be associated with a weighting function, which can be chosen after the calibration process.

- Receiver on top of clutter: Select "0 - No", unless you are calibrating a model to be used for fixed WiMAX
and LTE receivers. This option is only used for fixed receivers which are located on top of buildings.
Under Clutter Taken into Account, you can set the following parameters under Range:
- Max. distance: This parameter indicates the distance from the receiver for which clutter losses will be
considered via a weighting function, with an effect on the influence of clutter on total losses which diminishes
with distance from the receiver. Set this value within the typical range [150 m; 500 m] depending on the model
type you are currently calibrating, where the lower value corresponds to a dense urban model whereas the
upper value is compliant with a more rural model.
The effect of this value is to simulate the real diffraction along the path which a result of the several obstacles
located in front of the receiver. If you set this value to "0", clutter classes will be considered like in Hata models
where only the clutter class on which is located the receiver is considered in the path loss evaluation.
- Weighting Function: Select the weighting function which is the mathematical formula used to calculate the
weight of the clutter loss on each pixel from the pixel with the receiver in the direction of the transmitter, up to
the defined maximum distance.
DU = Dense Urban
U = Urban
Tx
Rx
DU DU DU U U U U U

Maximum Distance

Figure 4.14: Calculating the total clutter loss between the transmitter and the receiver

In the example in Figure 4.14:, the defined maximum distance indicates that only the clutter losses on the first
six pixels will be taken into account when calculating the total loss. How the losses on each pixel within the
maximum distance are taken into account when calculating the total loss depends on the weighting function.
There are four possible weighting functions:

- Uniform
- Triangular
- Logarithmic
- Exponential.
Figure 4.14: displays how the clutter loss of each pixel will be taken into consideration. In Figure 4.14:, the
value of each pixel is displayed as a function of its distance from the receiver. With the uniform weighting
function, the clutter loss of each pixel within the maximum distance is simply added. With the other three
functions, the clutter loss of each pixel diminishes according to a mathematical formula. For more information
on the weighting functions and on the mathematical formulas used, see the Technical Reference Guide.

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Figure 4.15: Comparative behaviour of the clutter weighting functions in the SPM

Note: If clutter losses are not taken into account by the propagation model, clutter loss weighting
will not have an effect.

Under Parameters per clutter class, you can set the following parameters for each clutter class:

- Losses: Clutter losses will be calibrated.

- Clearance: Clutter clearance is only used when clutter height information from the clutter class file is used for
a clearance distance from the receiver when calculating diffraction.
- Rx Height: Ensure that the Rx Height is set to "(default)." The default receiver height is defined on the
Receiver tab of the Predictions folder Properties dialogue.

4.2.3 Running the SPM Calibration Process

There are two different calibration processes available. The goal of both processes is to reduce the mean error and
standard deviation of measured values versus calculated values. Independently of how you calibrate the standard
propagation model, it must be able to give correct results for every CW measurement point from the same geographical
zone, including CW measurement points that were not used to calibrate the standard propagation model. The difference
between the processes lies in how they accomplish the task:
• Automatic: Using acceptable data ranges that you set for the K1 to K6 variables, the automatic calibration
process attempts to reduce the mean error and standard deviation of measured values versus calculated values.
The automatic calibration process selects the method for calculating diffraction.
• Assisted: The assisted calibration process enables you to display the correlation of the K1 to K6 variables to the
mean error. There are some parameters that have more influence on error than others. You will usually proceed
by adjusting the value of the variable that correlates the most with the mean error to reduce the mean error and
standard deviation.
Both methods have their advantages. The automatic calibration process is simpler and more straight-forward. As well, the
results are constrained by limits you set. On the other hand, any solution given by the automatic calibration process is a
purely mathematical solution. So, before using a propagation model calibrated using only the automatic calibration
process, you should ensure of its relevance in a realistic environment.
The assisted calibration process relies on your input to set the values for the K1 to K6 variables. It gives you more control
over the calibration process but, because there is no defined range set, it can lead to a mathematical solution that bears
little relation to the physical environment. For this reason, the assisted calibration process is better suited to advanced
users who can apply their experience to the calibration process.
The recommended approach is to combine both calibration methods, by first using the automatic calibration process and
then fine-tuning the results of the calibrated propagation model using the assisted calibration method.
Both calibration processes are started using the same method.
To start the calibration process:
1. Click the Modules tab in the Explorer window.
2. Click the Expand button ( ) to expand the Propagation Modules folder.
3. Right-click the copy of the SPM that you want to calibrate. The context menu appears.
4. Select Calibration from the context menu (see Figure 4.16:). The Calibration Wizard window appears.

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Figure 4.16: Calibration launching on SPM model

5. Select the CW measurement paths that you decided to use for the calibration process (see Figure 4.17:). For
information on selecting CW measurement paths, see "Selecting Base Stations for Calibration and for Verification"
on page 52.
6. Select the calibration method:
- Automatic Calibration: When you select the automatic calibration method, you set the acceptable ranges for
variables and Atoll attempts to find a solution that minimises the error between measurements and predictions
and their standard deviation.
- Assisted Calibration: When you select the assisted calibration method, you can adjust each variable of the
propagation model using a correlation matrix which indicates which variables have the greatest impact on the
mean error.
When you select the assisted calibration method, you can select the check boxes of LOS or NLOS to indicate
whether you want to work with the LOS or NLOS sets of variables or with both.

Figure 4.17: Path and Calibration method selection for SPM Calibration

7. Click Next.
- If you selected Automatic Calibration, continue with "The Automatic Calibration Wizard" on page 57.
- If you selected Assisted Calibration, continue with "The Assisted Calibration Wizard" on page 59.
Note: The filters defined in the properties of each CW measurement path will be taken into
account in the calibration process.

4.2.3.1 The Automatic Calibration Wizard

After you have selected the automatic calibration method in "Running the SPM Calibration Process" on page 56, you can
continue with the automatic calibration wizard:
1. For each parameter and method (i.e., HTx and diffraction method) you want to calibrate, select the check box of
the parameter in the Parameter column.

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Figure 4.18: Range definition for SPM parameters during calibration

2. Define the range of each Ki parameter to be calibrated:

a. Click the Ki parameter in the Parameter column.

b. Click the Define Range button. The Define Range dialogue appears.
c. Set the Min. Value and Max. Value for the variable.
Here are default and recommended ranges for Ki parameters:

Ki Minimum Maximum
K1 0 100
K2 20 70
K3 -20 20
K4 0 0.8
K5 -10 0

Important: Leave the K6 parameter unselected. You can set the K7 parameter to "0" as well as it has
little influence on the performance propagation model.

d. Click OK.
3. Click Next to start the calibration process.
After the calculations have completed, a results window appears with the previous parameters and methods and
current parameter values and methods (see Figure 4.19:).

The previous and the current statistics are also displayed in terms of the root mean square, the standard deviation
and the mean error (error = predicted - measured).

Figure 4.19: SPM Comparative Calibration Results

4. Click Commit to apply the results of the calculation process (i.e., calibrated Ki, methods, and clutter losses) to the
initial propagation model.

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4.2.3.2 The Assisted Calibration Wizard

After you have selected the assisted calibration method in "Running the SPM Calibration Process" on page 56, you can
continue with the assisted calibration wizard.
The table under Variables in the Assisted Calibration dialogue displays for each parameter to be calibrated (K1, K2, K3,
K4, K5, K6 and K7) the correlation of the variables (log(d), log(HTxeff), Diff, log(d)log(HTxeff), HRxeff, log(HRxeff) with the
global error. The variable with the highest absolute correlation is the variable that is the most correlated with error. In other
words, this variable has the highest impact on the error and modifying this variable with have the greatest improvement
on the global error. When you select an entry under Variables, the graph on the right shows the regression line
corresponding to the variable for all the points (see Figure 4.20:). The X-axis corresponds to the variable (in ascending
order for all paths) and the Y-axis indicates the corresponding error.

Figure 4.20: Table listing the correlation of the SPM variables to the global error

When the correlation coefficient is close to one, the graph showing the regression is a vertical line; this indicates that the
global error depends strongly on the variable. When the correlation coefficient is close to zero, the points are scattered
around a horizontal line; this indicates that the correlation between the error and the variable is limited. It means that if the
variable if modified, this will not improve the error.
To use the assisted calibration wizard to reduce the mean error:
1. In the table, select the variables that you want to modify to reduce the mean error. To select more than one
variable, press CTRL as you click the other variables.
2. Click the Identify button. The assisted calibration wizard attempts to bring the correlation as close to zero as
possible. Under Statistics, you can compare the Root Mean Square, the Average, and the Standard Deviation
before and after.
If you want to adjust the losses per clutter class to reduce the mean error, the maximum distance, as defined under
Range on the Clutter tab of the propagation model’s Properties dialogue, must be set to "0". If the maximum
distance is set to any other distance, Atoll will ask you if you want to force the maximum distance to "0" before
letting you modify the losses per clutter class.

Note: If you are not satisfied with the changes made when you clicked Identify, you can undo them
by clicking Reinitialise.

Calibration is complete when the Root Mean Square, the Average, and the Standard Deviation are as close to
zero as possible.

3. Click Statistics to view a report on the statistics of the propagation model, using the current parameter values.
Under Model Parameters, the settings defined in General and Clutter tabs of the propagation model’s Properties
dialogue are summarized: formulas, methods, distances, diffraction method, and losses per clutter class.

Under Global Statistics, the number of CW measurement points which match any filter criteria is given, along
with the mean, standard deviation, and minimum and maximum values for variables such as the error, error (LOS),
error (NLOS), log(d), log(HTxeff), Diff, log(d)log(HTxeff), and HRxeff.

Under Statistics per Clutter Classes, number of points, mean, and standard deviation for each clutter class are
given.

Under Correlation Matrix, is a matrix of all parameters.

4. When you are satisfied with the results, click Commit to update the Ki factors of the propagation model with the
changes.

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4.3 Calibrating Hata Models

When the CW measurement data have been imported into the Atoll calibration project and prepared as explained in
"Setting Up Your Calibration Project" on page 33, you can calibrate the Okumura-Hata and Cost-Hata Models. Atoll offers
both an identical automatic calibration wizard.

4.3.1 Quality Targets

The quality of the final calibrated propagation model depends strongly on the quality of the CW measurements used in the
calibration process. Therefore, you will only be able to meet the following quality targets if the CW measurements used in
the calibration process are of good quality, the provided radio data are correct, and the described calibration procedure is
followed.
Calibration Sites:
• Global mean error on calibration sites: < 1 dB
• Global standard deviation on calibration sites: < 8 dB
• Mean error on each calibration site: < 2.5 dB
• Standard deviation on each calibration site: < 8.5 dB
Verification Sites:
• Global mean error on verification sites: < 2 dB
• Global standard deviation on verification sites: < 8.5 dB

4.3.2 Setting Initial Parameters in the Hata Models

Before starting the calibration process, you have to set a few parameters in Hata Models.

Tip: After you have set initial parameters, you can retain the original copy of the Hata Model by
creating a copy of the considered Hata Model and calibrating the copy instead. This allows you to
restart calibration from the original version if you should need to. You can create a copy of an Hata
Model by right-clicking the appropriate model folder on the Modules tab of the Explorer window and
selecting Duplicate from the context menu.

The Okumura-Hata model is suited for predictions in the 150 to 1000 MHz band over long distances (from one to 20 km).
It is best suited to GSM 900, and CDMA 1xRTT radio technologies.
The Cost-Hata model is suited for coverage predictions in the 1500 to 2000 MHz band over long distances (from one to
20 km). It is best suited to DCS 1800 and UMTS radio technologies.
Hata models in general are well adapted to the urban environment. You can define several corrective formulas and
associate a formula with each clutter class to adapt the Hata model to a wide variety of environments. You can also define
a default formula to be used when no land use data is available. Additionally, you can consider diffraction losses based on
the DTM.
In this section, the following initial Hata Model parameters are explained:
• "Defining General Settings" on page 60
• "Selecting an Environment Formula" on page 61
• "Creating or Modifying Environment Formulas" on page 61.

4.3.2.1 Defining General Settings

To set general parameters on the Okumura-Hata propagation model:
1. Click the Modules tab of the Explorer window.
2. Click the Expand button ( ) to expand the Propagation Models folder.
3. Right-click the Hata Model to set-up. The context menu appears.
4. Select Properties from the context menu. The Properties dialogue appears.
5. Click the Parameters tab. You can modify the following settings:
- Add diffraction loss: The Okumura-Hata propagation model can take into account losses due to diffraction,
using a 1-knife-edge Deygout method, and using the ground altitude given in the DTM. For detailed
information on the Deygout method, see the Technical Reference Guide. The calculations take the curvature
of the earth into account. Select "1 - Yes" if you want the propagation model to add losses due to diffraction.
You can weight this diffraction for each Hata environment formula (See "Creating or Modifying Environment
Formulas" on page 61)
- Limitation to free space loss: When using a Hata-based propagation model, it is possible to calculate a
theoretical path loss that ends up being lower than the free space loss. In Atoll, you can define any Hata-
based propagation model to never calculate a path loss that is lower than the calculated free space loss per
pixel. Select "1 - Yes" if you want the propagation model to limit the path loss calculated per pixel to the
calculated free space loss.
6. Click OK.

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4.3.2.2 Selecting an Environment Formula

The Okumura-Hata propagation model can use an environment formula appropriate to each clutter class when calculating.
You can assign a default formula that Atoll can use for all clutter classes for which you have not assigned an environment
formula or if you do not have clutter classes in your Atoll document.
To select environment formulas:
1. Click the Modules tab of the Explorer window.
2. Click the Expand button ( ) to expand the Propagation Models folder.
3. Right-click Okumura-Hata. The context menu appears.
4. Select Properties from the context menu. The Properties dialogue appears.
5. Click the Configuration tab.
6. Under Formulas assigned to clutter classes, select the Default formula row. Under this grid, choose the
appropriate formula in the formula scrolling list.
Atoll uses the default environment formula for calculations on any clutter class to which you have not assigned
an environment formula or if you do not have clutter classes in your Atoll document.

7. For each clutter class under Formulas assigned to clutter classes, select the corresponding row. Under this
grid, choose the appropriate formula in the formula scrolling list and an additional loss (in dB). This additional loss
acts as correction on the loss calculated by the chosen formula.
For information on modifying the selected formula, see "Creating or Modifying Environment Formulas" on page 61.

8. Click OK.
Note: Additional losses can be evaluated using the Automatic Calibration Wizard. For information
on the Automatic Calibration Wizard, see "Running the Hata Calibration Process" on
page 61.

4.3.2.3 Creating or Modifying Environment Formulas

Several environment formulas are available with the Okumura-Hata propagation model to model different environments.
You can modify existing environment formulas used by the Okumura-Hata propagation model or create new environmental
formulas.
To create or modify an environment formula:
1. Click the Modules tab of the Explorer window.
2. Click the Expand button ( ) to expand the Propagation Models folder.
3. Right-click Okumura-Hata. The context menu appears.
4. Select Properties from the context menu. The Properties dialogue appears.
5. Click the Configuration tab.
6. Click the Formulas button. The Formulas dialogue appears. You can do the following:
- Add: To create a new formula, click the Add button and modify the parameters of the formula.
- Delete: To delete a formula, select the formula and click the Delete button.
- Modify: To modify an existing formula, select the formula and modify the parameters.
7. Click OK to save your changes and close the Formulas dialogue.
8. Click OK.
Notes:
• You can weight the diffraction loss by setting the diffraction multiplying factor within the range
[0;1].
• Constant values and diffraction multiplying factor can be evaluated using the Automatic Calibra-
tion Wizard for each environment formula. For information on the Automatic Calibration Wizard,
see "Running the Hata Calibration Process" on page 61.

4.3.3 Running the Hata Calibration Process

The goal of the automatic calibration process is to reduce the mean error and standard deviation of measured values
versus calculated values. Independently of how you calibrate the standard propagation model, it must be able to give
correct results for every CW measurement point from the same geographical zone, including CW measurement points that
were not used to calibrate the standard propagation model.
To start the calibration process:
1. Click the Modules tab in the Explorer window.
2. Click the Expand button ( ) to expand the Propagation Modules folder.
3. Right-click the copy of the Hata Model that you want to calibrate. The context menu appears.
4. Select Calibration from the context menu (see Figure 4.21:). The Calibration Wizard dialogue appears.

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Figure 4.21: Calibration launching on Hata models

5. Select the CW measurement paths that you decided to use for the calibration process (see Figure 4.22:). For
information on selecting CW measurement paths, see "Selecting Base Stations for Calibration and for Verification"
on page 52.

Figure 4.22: Path and Calibration method selection for SPM Calibration

6. Click Next.
7. For each parameter you want to calibrate, select the check box of the parameter in the Parameter column.
8. Define the range of each parameter to be calibrated:
a. Click the parameter in the Parameter column.
b. Click the Define Range button. The Define Range dialogue appears.
c. Set the Min. Value and Max. Value for the variable.

Figure 4.23: Range definition for SPM parameters during calibration

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Here are default and recommended ranges for the calibrated parameters:

Parameter Minimum Maximum

A1 0 100
B1 0 100
Diffraction Factor 0 1

d. Click OK.
9. Click Next to start the calibration process.
After the calculations have completed, a results window appears with the previous parameters and methods and
current parameter values and methods (see Figure 4.24:).

The previous and the current statistics are also displayed in terms of the root mean square, the standard deviation
and the mean error (error = predicted - measured).

Figure 4.24: Hata Models Comparative Calibration Results

10. Click Commit to apply the results of the calculation process (i.e., calibrated Ai, diffraction multiplying factors and
Additional Losses) to the initial propagation model.

4.4 Analysing the Calibrated Model

Once the propagation model has been calibrated using either the automatic or the assisted method, Atoll offers several
methods to verify the calibration or to analyse its quality.
The first step is to calculate path loss matrices on the CW measurement paths using the calibrated propagation model, as
explained in "Calculating Path Loss Matrices Using the Calibrated Model" on page 63. Once you have path loss matrices
that have been calculated using the calibrated propagation model, you can analyse the calibrated model using the
following methods:
• "Displaying Statistics on CW Measurement Paths" on page 64
• "Using Display Settings to Analyse the Calibration" on page 65
• "Using the CW Measurement and the Point Analysis Tools" on page 66.

Calculating Path Loss Matrices Using the Calibrated Model

The first step in analysing the quality of the calibration process is to calculate signal losses on the CW measurement paths
using the newly calibrated propagation model. These path loss matrices will then be used to verify the accuracy of the
calibrated propagation model.
To calculate path loss matrices on the CW measurement paths:
1. Click the Data tab in the Explorer window.
2. Select the propagation model you calibrated:
a. Right-click the CW Measurements folder. The context menu appears.
b. Select Properties from the context menu. The Properties dialogue appears.
c. Select the Propagation tab and select the name of the propagation model you calibrated from the Propagation
Model list (see Figure 4.25:).
d. Click OK.

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Figure 4.25: Selecting the calibrated model for all CW measurement paths

3. Calculate signal levels for all CW measurement points:

a. Right-click the CW Measurements folder. The context menu appears.
b. Select Calculations > Calculate Signal Levels from the context menu. Atoll calculates the signal levels for
all CW measurement paths.

Figure 4.26: Calculating the signal levels on all CW measurement paths

Displaying Statistics on CW Measurement Paths

You can display the statistics on both the CW measurement paths used for calibration and on those used for verification.
By comparing these statistics to the quality targets (see "Quality Targets" on page 53), you can see whether the calibration
process was successful.
To display the statistics of a CW measurement path:
1. Click the Data tab in the Explorer window.
2. Right-click the CW Measurements folder. The context menu appears.
3. Select Display Statistics from the context menu. The Statistics dialogue appears (see Figure 4.27:).
4. In the Statistics dialogue, select the check boxes of the CW measurement paths of either the CW measurement
paths used for calibration or the those to be used for verification and click OK. The CW Measurements dialogue
appears (see Figure 4.28:).
The CW Measurements dialogue gives the average and standard deviation for all points, grouped by clutter class.
You can compare these statistics to the quality targets listed in "Quality Targets" on page 53.

Figure 4.27: Selecting on of the verification stations for the statistics

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Figure 4.28: Comparative statistics of the verification stations

Using Display Settings to Analyse the Calibration

You can analyse the quality of the propagation model calibration on the map, by examining areas where the error
(predicted minus measured) is very high.
To display the CW measurement points on the map according to the error:
1. Click the Data tab of the Explorer window.
2. In the CW Measurements folder, clear the display check box beside all CW measurement paths except the ones
you want to display.
This will limit the number of points displayed to the ones you want to examine.

3. Define the display settings of the CW measurement path:

a. Select the Display tab.
b. Set the Display Type to "Value Intervals" and select "Error (P-M)" from the Field list. For more information,
see "Defining the Display Type" on page 39.
4. Add the CW measurement points to the legend, as explained in "Adding CW Measurement Points to the Legend"
on page 40.
5. Select View > Legend Window. The Legend window appears.

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Figure 4.29: Distribution of error around a verification station

Using the CW Measurement and the Point Analysis Tools

By simultaneously using the CW Measurement Analysis Tool and the Point Analysis Tool, you can analyse the
following elements of a CW measurement path:
• The measured signal level
• The predicted signal level
• Diffraction
• The error
• The profile between the reference transmitter and the receiver.
To use the CW Measurement Analysis Tool and the Point Analysis Tool to analyse elements of a CW measurement
path:
1. Click the Data tab of the Explorer window.
2. In the CW Measurements folder, clear the display check box beside all CW measurement paths except the one
you want to display.
This will limit the number of points displayed to the ones you want to examine.

3. Right-click the CW measurement path you want to analyse. The context menu appears.
4. Select Open the Analysis Tool from the context menu. The CW Measurement Analysis Tool opens.

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Figure 4.30: Opening the CW Measurement Analysis tool

5. Select View > Point Analysis Tool. The Point Analysis Tool appears.

As you move the pointer ( ) along the CW measurement path on the map or in the CW Measurement Analysis
Tool window, the following information appears in the CW Measurement Analysis Tool window (see
Figure 4.31:):

- The measured signal level

- The predicted signal level
- The error
- The graph
You can select an additional characteristic of the CW measurement path from the list on the right.

The Profile tab of the Point Analysis Tool window displays the profile between a reference transmitter and the
selected CW measurement point. As well, Atoll displays the strength of the received signal from the selected
transmitter as well as any diffraction peaks.

Important: The propagation model used to generate the results on the Profile tab of the Point Analysis
Tool window is the model defined in the properties of the reference transmitter.

Note: You can also move through the CW measurement points by dragging the vertical line in the
CW Measurement Analysis Tool window that indicates the current CW measurement
point.

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Figure 4.31: CW Measurement Analysis

4.5 Finalising the Settings of the Calibrated SPM

The objective of the calibration process is to reduce the error between path loss values predicted by the propagation model
and real path loss values measured during the CW measurement survey. After calibration is complete, however, there are
still a few adjustments that will need to be made before the propagation model can be used.
If clutter classes are taken into consideration in the SPM, the first step in finalising the calibrated propagation model is
ensuring that a clutter loss is defined for all clutter classes. There are usually a few clutter classes that are not represented
in the area covered by the CW measurement survey, or that are not sufficiently represented and were, therefore, filtered
out. Nevertheless, losses must be defined for these clutter classes in order for the propagation model to be effective over
all areas. This is explained in "Defining Clutter Losses for Uncalibrated Clutter Classes" on page 68.
Once you have losses defined for each clutter class, you must define how the clutter losses will be weighted. The losses
defined per clutter class refer only to receiver pixel, not to total loss. When you calculate the total clutter loss, you have to
take into consideration the loss on pixels between the transmitter and the receiver. However, the influence of clutter
diminishes with distance from the receiver. Defining how clutter loss will be weighted is explained in "Clutter Tab" on
page 55.
The final step is ensuring that a model standard deviation has been set for each clutter class. As with clutter losses, no
standard deviation will have been calculated for clutter classes that were not represented or not sufficiently represented
in the CW measurement survey. To ensure accurate calculations with the calibrated propagation model, you must ensure
that all clutter classes have a defined model standard deviation. This is explained in "Defining the Model Standard
Deviation for Uncalibrated Clutter Classes" on page 70.

Defining Clutter Losses for Uncalibrated Clutter Classes

Clutter classes that were not represented, or were not sufficiently represented and were, therefore, filtered out, will not
have had clutter losses defined by the calibration process. The clutter loss for these clutter classes will remain at "0."
However, when clutter losses are used, leaving the clutter loss at "0" could lead to large errors when you use the calibrated
propagation model in areas where these clutter classes are present. Therefore, undefined clutter losses must be
extrapolated from other sources.
You can extrapolate undefined clutter losses from:
• Propagation models calibrated on other areas: If you calibrated a copy of the same propagation model using
CW measurements made on a different area, some, if not all, of the clutter classes that are uncalibrated in your
current propagation model may have been calibrated in the copy calibrated on the other area.
• Typical losses: You can extrapolate missing clutter losses from typical losses. It is important to remember that
the relative difference (between losses per clutter class) is more important than the absolute value of clutter losses
because the absolute value is dependent on the constant K1. As well, you must calculate and use a scaling factor

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between calibrated losses and typical losses. Additionally, clutter losses should be normalised on the most repre-
sentative clutter class in order to be able to compare them. In other words, if the best represented clutter class is
"Urban," then the clutter losses for "Urban" should be shifted to "0" for that clutter class and the calibrated clutter
class losses should be shifted to respect their relative difference from the clutter losses for "Urban" and the con-
stant K1 should be modified to compensate for the shift. For example, if "Urban," the best represented clutter class,
has a loss of "-3" and "Suburban" has a loss of "-7," when you shift "Urban" it to "0," you will have to shift "Sub-
urban" by a corresponding amount, i.e., the normalised loss for "Suburban" will be "-4." As well, if the value of K1
was 22, when you shift the clutter losses by 3, you will have to shift the value of K1 by a similar value, to give you
a value of 19, in order to compensate for the shift in clutter class losses.
The following table gives typical clutter losses, normalised for the Urban clutter class.

Clutter Class Loss

Dense urban From 4 to 5
Woodland From 2 to 3
Urban 0
Suburban From -5 to -3
Industrial From -5 to -3
Open in urban From -6 to -4
Open From -12 to -10
Water From -14 to -12

To extrapolate undefined clutter losses from other propagation models:

Important: Before you can extrapolate undefined clutter losses, you must ensure that the losses from
the other propagation model are normalised on the same clutter class as the clutter class
used for normalisation in the propagation model you are calibrating.

1. On the Modules tab of the Explorer window, right-click the copy of the propagation model calibrated on another
area. The context menu appears.
2. Select Properties from the context menu. The Properties dialogue appears.
3. Under Parameters per clutter class, on the Clutter tab, note the losses for all clutter classes that remained
uncalibrated in the copy of the propagation model you are currently calibrating.
4. Open the Properties dialogue of the propagation model you are currently calibrating.
5. Under Parameters per clutter class, on the Clutter tab, enter the losses for the clutter classes that remained
uncalibrated.
To extrapolate undefined clutter losses from standard values:
1. Using values that are present in both the calibrated propagation model and in the typical values, calculate the
scaling factor between the two sets of values.
To calculate the scaling factor, you use values existing in both the propagation model and in the typical values, for
example:

  Dense Urban, project  –  Suburban, project      Dense Urban, typical  –  Suburban, typical  

Note: Remember that it is the relative difference between losses per clutter class that is important.

2. Calculate the delta between the normalised clutter class loss in the typical values (i.e., "Urban") and the clutter
class loss that is undefined in the calibrated propagation model (i.e., the standard ).
3. Multiply this delta by the scaling factor between the project losses and the standard losses to calculate the clutter
loss for the project:

project = s tan dard  scaling factor

4. Add the delta of the project to the normalised clutter loss to obtain the value of the clutter class loss that is
undefined in the calibrated propagation model.
5. Repeat these steps for each clutter loss that is undefined in the calibrated propagation model.
For example, a project has the following clutter losses:

Dense Urban = 5
Urban = (0)
Suburban = 2

The clutter loss for Urban is undefined. To extrapolate from the known values using typical values, you must first
calculate the scaling factor, using the values existing in both the standard values:

  Dense Urban, project  –  Suburban, project      Dense Urban, typical  –  Suburban, typical  

In this case:

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3
  5 – 2    4 – – 4    ---
8

Using the scaling factor, you can calculate the delta between the Urban loss and the Dense Urban in the project:

project = standard  scaling factor

Or:

3
project =  4.5 – 0   ---  1.5
8

Subtracting the result of "1.5" from "5" gives us a clutter loss of "3.5" for Urban in this project.

Defining the Model Standard Deviation for Uncalibrated Clutter Classes

During the calibration process, model standard deviations were calculated for all calibrated clutter classes. You should use
these values to update the model standard deviation for each clutter class in the clutter class properties. Clutter classes
that were not represented, or were not sufficiently represented and were, therefore, filtered out, will not have had a model
standard deviation defined by the calibration process. You should update the model standard deviation for these clutter
classes if you calibrated a copy of the same propagation model on a different area that covered different clutter classes.

Figure 4.32: Description of the available clutter classes

4.6 Deploying the Calibrated Model

Once you have calibrated the propagation model, you can use it to make coverage predictions in Atoll documents that
cover the calibration area and that use the same frequency band that was used to calibrate the propagation model. With
Atoll you can copy the calibrated propagation model and paste it into another document. Atoll also enables you to quickly
deploy the calibrated propagation model to a defined group of transmitters in a document.

4.6.1 Copying a Calibrated Model to Another Document

You can copy a calibrated propagation model from the calibration document to another Atoll document.
Important: Remember that the calibrated propagation model is valid only for the area and frequency
band on which it was calibrated. If you use it on another

To copy a calibrated propagation model to another document:

1. Open the following Atoll documents:
- The Atoll document with the calibrated propagation model
- The Atoll document into which you want to copy the calibrated propagation model.
2. Click the Window menu and select the Atoll document with the calibrated propagation model.
3. Copy the calibrated propagation model:
a. On the Modules tab of the Explorer window, click the Expand button ( ) to the left of the Propagation
Models folder to expand the folder.
b. Right-click the calibrated propagation model. The context menu appears.

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c. Select Copy from the context menu. The calibrated propagation model is copied to the clipboard.
4. Click the Window menu and select the Atoll document into which you want to copy the calibrated propagation
model.
5. Paste the calibrated propagation model:
a. Select the Modules tab of the Explorer window.
b. Press CTRL+V. The calibrated propagation model is pasted into the Atoll document.
You can verify that the calibrated propagation model has been pasted successfully by clicking the Expand button
( ) to the left of the Propagation Models folder to expand the folder. The calibrated propagation model is now
visible in the Propagation Models folder.

4.6.2 Deploying a Calibrated Model to Transmitters

You can now deploy the calibrated propagation model to all transmitters corresponding to the calibration area and
frequency band. You can assign the calibrated propagation model in several different ways but, when you are assigning
it to a large number of transmitters, it is easiest to use the Transmitters table.
To deploy a propagation model using the Transmitters table:
1. Filter out the transmitters outside of the area over which you will be deploying the calibrated propagation model
by creating a filtering polygon that selects all the transmitters within the area:
a. On the Geo tab of the Explorer window, click the Expand button ( ) to the left of Zones folder to expand the
folder.
b. Right-click the Filtering Zone folder and select Draw from the context menu. The pointer changes to the

polygon drawing pointer ( ).

c. Click on the map to start drawing the filter polygon. Click each time you change the angle on the border
defining the outside of the polygon.
d. Close the polygon by clicking twice. The transmitters outside of the selected zone are filtered out. On the Data
tab of the Explorer window, the Transmitters folder appears with a special icon ( ), to indicate that the
folder contents have been filtered. Only the transmitters within the filtering zone will now appear in the
Transmitters table.
2. Open the Transmitters table:
- On the Data tab of the Explorer window, right-click the Transmitters folder and select Open Table from the
context menu. The Transmitters table appears.
3. If necessary, sort the entries in the Transmitters table by frequency band:
- In the Transmitters table, click the title of the Frequency Band column to sort the entries by frequency band.
4. Select the calibrated propagation model for all records that will use it:
a. In the Main Propagation Model column, select the calibrated propagation model.
b. Starting with the record you have just changed, click and drag to select all records that will have the same
propagation model.
c. Select Edit > Fill > Down. The entry under Main Propagation Model changes to the value in the first record
of the selected transmitters.
Note: If the result was not what you expected, select File > Undo and repeat the steps.

d. If you want to assign the calibrated propagation model to the extended propagation model as well, repeat
these steps with the entries in the Extended Propagation Model column.

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