Technological Institute of the Philippines

Electronics Engineering Department

PSK and QAM Generation

Experiment No. 4

OBJECTIVES:
1. To be able to generate PSK and QAM.
2. To be able to understand and explain the simulation process and the functions of each
blocks used.
3. To be able to explain the results of the waveform.

Course Code/Section: ECE 015 / ECE31S2

Group No.: 6

Members: Signatu Interpretation of Conclus Overall

Data and Results ion
re Lab
Grade

Alinea, Arns Vhinzy

Dacir, Renz Marlo
Viduya, Tan Hay II

Data and Results Group Grade:

Question and Answer Group Grade:

Engr. Dennis Jefferson A. Amora

Instructor

Date Performed: November 14, 2020

Date Submitted: November 15, 2020
Simulation set up of PSK and QAM:

Figure 1. Simulation set up for PSK and QAM

MODULATION SCHEME OUTPUT

4-PSK
8-PSK

16-PSK

4-QAM

8-QAM
 16-QAM

Data and Results:

4 - PSK Simulation Setup and Constellation

This setup was made with simulating 4-PSK in mind. By simply changing channel A’s output,
the constellation for 4-PSK can be seen. This in itself shows what a 4-PSK constellation
should look like, and as such displays all its visual characteristics, such as having 4 points
located at an equal distance from each other, forming a diamond shape. The four points
represent the output voltages usually seen in a 4-PSK setup.
 4-PSK Waveform

The PSK waveform looks chaotic, to say the least. This is attributed to the fact that 4-PSK
deals with a lot more information than normal PSK. Differing amplitudes indicate a level of
complexity not seen in more basic forms of digital modulation.

4-QAM Simulation Setup and Constellation

This setup was made with simulating QAM, specifically 4-QAM. By simply changing
channel A’s output, the constellation for 4-QAM is easily perceived. This in itself shows what
a 4-PSK constellation should look like, and as such displays all its visual characteristics, such
as having 4 points located at an equal distance from each other and to the origin, forming a
rectangular shape, as opposed to the diamond shape of the 4-PSK setup. The four points
represent the output voltages usually seen in a 4-QAM setup.
 4-QAM Waveform

The 4-QAM Waveform looks quite odd compared to a normal waveform, but this is due to the
In-phase (I) and Quadrature (Q) signals working together. The differing time intervals in the
amplitude are also caused by the Q signal and the I signal. This provides the characteristic
results expected from a QAM setup.

8 - PSK Simulation Setup

As a source carrier for the whole 8- the 100 kHz TTL level signal was employed.
Channels A and B have been used in XY mode where Channel A is located
to view the diagram of the constellation. The modules that have been used is the Sequence
Generator (Pseudorandom Sequence Generator) produces two independent pseudorandom
sequences X and Y with the use of a common external clock signal. Next module is M-level
Encoder it has a continuous TTL-level sequence of data bits (where L = 2, 4 or 3) is grouped
together as a set of 'L' bits. Each set of 'L' bits is encrypted in a pair of baseband M-level, q & I
signals, this q & I signal pair can be represented in a signal-state-space diagram or constellation
as 2L single dots (or symbols). There are six different encoding modes available for 4-QAM, 8-
QAM, 16-QAM, 4-PSK, 8-PSK, 16-PSK signals selected via the front panel switches. In this
case 8 - PSK was used.

8 - PSK signal constellation using TIMS

8-PSK have 8 possible phases, as shown at the characteristic constellation for this modulation
type, which can be carried at a given time by the carrier. The eight phases have the same phase
vectors separated by 45 degrees.
 8 - PSK Waveform

PSK, information transmitted by phase changes, since it cannot be established absolute phase.
The phase can change once in every period, while the amplitude remains constant. Eight
possible phases exist in 8-PSK and thus three bits of information transmitted in each slot. The
signal bandwidth is determined by the rate of change (baud), but the output or bit rate of 8-PSK
is 3 times the baud rate.
 8 - QAM Simulation Setup

As the source clock for blocks, the 8.3kHz CLK signal was used. They've been to be used.
Channels A and B were used to show a constellation diagram when Channel A is in XY mode.
The modules that have been used is the Sequence Generator (Pseudorandom Sequence
Generator) produces two independent pseudorandom sequences X and Y with the use of a
common external clock signal. Next module is M-level Encoder it has a continuous TTL-level
sequence of data bits (where L = 2, 4 or 3) is grouped together as a set of 'L' bits. Each set of 'L'
bits is encrypted in a pair of baseband M-level, q & I signals, this q & I signal pair can be
represented in a signal-state-space diagram or constellation as 2L single dots (or symbols).
There are six different encoding modes available for 4-QAM, 8-QAM, 16-QAM, 4-PSK, 8-
PSK, 16-PSK signals selected via the front panel switches. In this case 8 - QAM was used.
 8 - QAM signal constellation using TIMS

The XY graph was used to identify 8 points. In each quadrant of the graph consisting of 2
points with phases of similar importance only amplitude value is the difference. It is easy to
notice that the diagram is somehow reflected because the only major difference is Phase
polarity.
 8 - QAM Waveform

QAM, quadrature amplitude modulation provides some significant benefits for data
transmission, amplitude and phase variations are present in this total signal, consisting of the
combination of both I and Q carriers. Because both amplitude and phase variations are present,
the mixture of amplitude and phase modulation can also be considered. As the QAM order
increases, the spacing of the constellation diagram between the various points decreases and the
possibility of data errors is greater.

Conclusion:
Task Distribution:

Members Task Performed

Alinea  Simulation & Documentation

Dacir  Simulation & Documentation

Viduya  Simulation & Documentation