CHAPTER ONE

INTRODUCTION

1.1 BACKGROUND OF THE SYUDY

Mobile phones are everywhere these days, and according to the Cellular Telecommunications
and Internet association, almost 195 million people in the United States had mobile-phone
service in October 2005. Mobile phones are also ubiquitous in Nigeria.
It’s great and awesome to be able to call anyone at anytime, but unfortunately, lecture halls,
worship centers, movie theatres, concerts, shopping malls e.t.c. all suffer from the spread of
mobile phones because not all mobile phone users know when to stop talking. However, for
those that are tired of hearing endless mobile phone conversations or constantly being interrupted
by incessant phone ring outs, a mobile phone jammer seems like the perfect device.
A Mobile Network Jammer, also known as Mobile Phone Jammer or Wireless Signal Jammer is
a device or an instrument that is used to prevent mobile phones from sending or receiving signals
from base stations, by transmitting a dirty (noise) signal on the same frequency at which the
mobile phone operates. The jamming succeeds when the mobile phones in the area where the
jammer is located are disabled from making or receiving calls and other smart phone activities
(sending or receiving text massages and receiving internet services). (Uno et al 2013)
These devices can be used in practically any location, but are found primarily in places
where a phone call would be practically disruptive because silence is expected. They can also be
used where bombs are being planted and detonated by GSM or Radio Frequency signals, by
jamming the signals required for the detonation of the bomb, and can also be used to checkmate
examination malpractice (Ahlin 2012). They were first developed and used by the military to
deny the successful transport of information from the sender (tactical commanders) to the
receiver (the army personnel) and vice-versa, and also by law enforcement to interrupt
communications between criminals and terrorists, while some were also designed to foil the use
of certain remotely detonated explosives (Nihad 2009).

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Nowadays the mobile jammer devices are becoming civilian products rather than electronic
warfare devices, because with the increasing number of the mobile phone users, the need to
disable mobile phones in specific places where the ringing of mobile phone would be disruptive
and where the use of mobile phones is prohibited has also increased (Husin 2010). Some of these
places have also been listed above.
As stated earlier, a mobile phone jammer blocks the use of mobile phones by sending out radio
waves (signals) along the same frequencies that mobile phones operate. This creates disturbance
(noise) for the mobile phones by interfering with the communication between the phones and
their base stations, to render the phones unusable (Okoye et al 2013).
Mobile phone jamming devices are an alternative to more expensive measures against mobile
phones, such as Faraday cages, which are mostly suitable as built in protection for structures
(Nihad 2009).
Mobile network jammer is an illegal device in many countries, and this is due to the fact that the
device blocks the signal approved by the government as a legal communication transmission
system (Ahlin 2012). According to the Federal Communications Commission (FCC) in the USA,
"The manufacture, importation, sale, or offer for sale, of devices designed to block or jam
wireless transmissions is prohibited". Also, according to the National Communications
Commission (NCC) in Nigeria, “The manufacture, importation, sale, or offer for sale, of devices
designed to block or jam wireless transmissions is prohibited”. However, the design and testing
of this device that will jam MTN, GLO, ETISALAT and AIRTEL networks in this project, is
done solely for academic purpose, precisely the presentation of Bsc. Project work. There is no
intention of manufacturing or selling this device anywhere.

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1.2 STATEMENT OF THE PROBLEM

Due to the increasing sophistication of mobile technology in the present day world, virtually
everyone now makes use of a mobile phone. Mobile phones are very important information and
communication tools, and in some countries like Nigeria, most citizens can own more than one,
making it difficult to minimize their use at some point. With the use of these mobile phones
everywhere, it becomes an annoying and a distracting device if activated in a work, study and
prayer environment e.t.c.
Also, modern technology has contributed to the sophistication of bombs which are being
triggered by GSM and Radio signals.
Lastly, in various kinds of exams, mobile phones are a major tool for examination malpractice,
especially in the Jamb exam, WAEC and university semester exams.
Signal jamming devices can be placed, rather than mounting or drawing images that may do little
or no good, as shown in figure 1 below.

Figure 1: Typical sign used in places where mobile phones are not allowed.

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1.3 AIM AND OBJECTIVES OF THE STUDY

This project aims at the designing, constructing and testing a simple mobile network jammer.

OBJECTIVES
The objectives are as follows:
 To build a module to prevent mobile phones from receiving and transmitting frequency
signals to the base station.
 To build a module to block mobile phones from ringing in places where silence and
concentration is needed like churches, libraries and conference rooms, e.t.c.
 To build a module to effectively disable mobile phones within the defined regulated
zones without causing any interference to other communication outside the range
 To build a module to disconnect mobile services from specified service providers

1.4 SIGNIFICANCE OF THE STUDY

Most times, unnecessary scenes are created in environments where all manner of individuals
with unique behaviors are welcomed. This being so because unruly individuals seizes the
platform to express themselves by trying to override the system and take a warning notice for
granted, or what may be referred to as operating above the law, which further results to
unnecessary arguments and distractions that may temporarily stop the course of the program in
that place. This type of scenario can be found in places like churches, conference rooms and
most especially in banks, where laws and notice has been put in place to prohibit the use of
mobile phones.
There could be no need for all that, unruly individuals could be handled in a better, silent and
frustrating way, distractions from unintended ring-outs could also be avoided without notice and
everything goes on rightly in such places as if nothing tries to go wrong. Everything also goes on
seamlessly, because a system where there are constant interruptions and distractions may incur
serious disadvantages. The brain that will be behind this unseen coordination is known as a
Mobile Network Jammer.

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1.5 SCOPE OF THE STUDY

 This project only focuses on blocking mobile networks that operates at the frequency of
450 MHz and above. However, it will not transmit up to 900 MHz and above because the
components required to transmit such high frequencies are very scarce, almost
unavailable in Nigeria.
 Secondly, the device will be able to block signals from the four main network providers
in Nigeria, namely: ETISALAT, MTN, GLO and AIRTEL. This is because they are the
main and most common service providers in Nigeria.
 The device can restrict mobile phone signal from 30m and even higher in diameter, and
therefore jams any mobile phone that is within the meters from the transmission point.
 The device only disrupts mobile phone signals, but has no influence on other electronic
equipment, audio equipment and human body etc.
 Finally, the jamming effect can vary widely based on factors such as proximity to towers,
indoor and outdoor setting, presence of buildings and landscape, temperature and
humidity also play a role.

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 CHAPTER TWO
LITERATURE REVIEW

2.1 INTRODUCTION

Electronic devices are part of our daily lives and some of them have become necessary an
essential for our needs like computer system, microwave, home theater, fridge, ETC.
In the past few years, a new device has made its place in this list and it will not be wrong to say
that it is now part of our lives. That device is Mobile or Cell Phone. The making of mobile phone
have increased exponentially, and now more than half of the population of the world use Mobile
phones in their daily routine (Nihad 2009) and it will not be opposed if it is said that Mobile
phones have many benefits. However, every thing is of two aspects, one is good and the other is
bad and we always strive to remedy the bad aspects.
Jamming devices overpower the cell phone by transmitting a signal on the same frequency as the
cell phone and at a high enough power that the two signals collide and cancel each other out.
Since mobile phones are designed to add power if they experience low-level interference, the
jammer must also recognize and match the power increase from the phone (Husin 2010).
Older jammers sometimes were limited to working on phones using only analogue or older
digital mobile phone standards, but newer models such as the double and triple band jammers
can block all widely used phone systems and are even very effective against newer phones which
hop to different frequencies when interfered with (Nihad 2009). Analogue mobile phones often
suffered from chronically poor reception and could even be disconnected by simple interference
such as high frequency (noise), increasingly sophisticated digital phones led to more elaborate
counters like the double and the triple band jammers.
GSM (Mobile Phone) jammers are usually simple devices with typically only a switch to turn it
on and off, a light to show that it is working and an external antenna to send the signal. If the
jammer is more sophisticated, it might include controls to set the jamming for varied frequencies
or strengths. Small GSM jammers are usually powered by batteries. Often, the batteries are even
the same as mobile phone batteries. Larger GSM jammers are electrically powered.
GSM jammers typically have a range of (between 50 and 80) feet, meaning that they will only
successfully jam mobile phones that are within this range. As soon as the mobile phone travels
out of range, the signal will return and the phone can be used again.

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More sophisticated mobile phone jammers might have larger ranges, typically associated with
higher power (wattage) jammers (Ahlin 2012).
Although the range of a portable or pocket sized mobile phone jammer is not as broad as larger
fixed models, they are large enough to help bring peace and quiet to a specified environment.
There are concerns that crudely designed jammers may disrupt the functioning of medical
devices such as pacemakers, but most of the devices in common use, including mobile phones,
operate at a very low power output (less than one watt) to avoid causing any problems.

2.2 OVERVIEW OF MOBILE PHONE

A mobile phone is a portable telephone which receives or makes calls through a cell site (base
station), or transmitting tower. They transmit and receive signal through radio waves.
Modern mobile phone networks use cells because radio frequencies are a limited, shared
resource. Cell sites and handsets change frequency under computer control and use low power
transmitters so that the usually limited number of radio frequencies can be simultaneously used
by many callers with less interference (Wikipedia 2014).
Ahlin (2012) clearly explains the brief history of mobile phones chronologically as follows:
Mobile Telephone Service (1946 - 1984): This system was introduced on 17 th of June, 1946, also
known as Mobile Radio-Telephone Service. This was the founding father of the mobile phone.
This system required operator assistance in order to complete a call. These units do not have
direct dial capabilities.
Improved Mobile Telephone System (1964-present): This system was introduced in 1969 to
replace MTS. IMTS is best known for direct dial capabilities. A user was not required to connect
to an operator to complete a call. IMTS units will have a keypad or dial similar to what you will
find on a home phone.
Advanced Mobile Phone System (1983-2010): This system was introduced in 1983 by Bell
Systems; the phone was introduced by Motorola in 1973 and released for public use in 1983 with
the Motorola 8000. Advanced Mobile Phone System (AMPS) also known as 1G is an
improvement of IMTS. Later on, the AMPS was upgraded to Digital Advanced Mobile Phone
System (D-AMPS), which made use of 2G standard, and then further improvement brought

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about more advanced digital wireless networks known as CDMA2000 or Global System for
Mobile Communications (GSM), which allow for higher capacity data transfers for services such
as WAP, Multimedia Messaging System, and wireless internet access. GSM uses a variation of
time division multiple access (TDMA) and is the most widely used of the three digital wireless
telephone technologies (TDMA, GSM, and CDMA).

However, the mobile phone jammer being treated in this project will be effective for the
Advanced Mobile Phone System (AMPS), D-AMPS, but mostly effective for GSM, since it
operates at the same frequency with GSM, and also GSM accounts for about 70% of the global
mobile market (Ahlin 2012).
It is worthy to note that some phones are capable of supporting AMPS, D-AMPS and GSM all in
one phone (Wikipedia 2014).
Generally, a mobile phone works by communicating with its service network through a cell
tower or base station. Cell towers divide a city into small areas, or cells, and as a mobile phone
user moves down the street, the signal is handed from tower to tower (Husin 2010).
Mobile phones are full-duplex devices, which means they use two separate frequencies, one for
talking and one for listening simultaneously, which also implies that they use one
band(frequency) to send signal to the base station (upward signal) and another band to receive
signal from the base station (downward signal). The upward signal refers to transmission from
mobile phone to base station while the downward signal refers to transmission from base station
to mobile phone. The Jammer blocks any one of this frequency by transmitting relatively high
power signals (noise) on the same frequency which the mobile phone operates, and when these
two frequencies collide, they cancel out each other, which then results to the inability of the
mobile phone to identify the signal transmitted from the base station (downward signal), and
then it keeps searching for signal and so it can be seen on the mobile phones display screen “no
network coverage” or “searching for network” or “no service” , and same situation applies to all
phones in the 100m radius of the jammer. It is worthy to note that the jammer easily blocks the
frequency transmitted with the downward signal because base stations are far away from the
phone, and the signal coming from them that reaches the mobile phone is of low power
(Uno et al 2013).
Less complex jammers block only one of the frequencies used by mobile phones, which in turn
has the effect of blocking both frequencies, because the phone is tricked into thinking that there

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is no service because it can receive only one of the frequencies, while sophisticated jammers can
block several types of networks at once to head off dual-mode or tri-mode phones that
automatically switch among different network types to find an open signal.
It is also necessary to note that mobile phones are designed to add power if they experience low-
level interference, so the jammer must also recognize and match the power increase from the
phone. The power of the jammer's effect can vary widely based on factors such as proximity to
base stations, indoor and outdoor settings, presence of buildings and landscape, even temperature
and humidity play a role (Husin 2010).

2.3 MOBILE NETWORKS

A mobile network or a cellular network is a wireless radio network distributed over land areas
called cells, where each cell is served by at least one fixed-location transceiver, known as cell
site or base station (Wikipedia 2014).
It is the network that allows mobile phones to communicate with each other, and it works using a
series of cells, each served by a base station which receives and sends radio signals to the mobile
phones (Legget 2014). In a cellular network, each cell uses a different set of frequencies from
neighboring cells, to avoid interference and provide guaranteed bandwidth within each cell.
When joined, these cells provide radio coverage over a wide geographic area. This enables a
large number of portable transceivers (mobile phones, pagers, e.t.c.) to communicate with each
other and also with fixed transceivers and telephones anywhere in the network, via base stations,
even if some of the transceivers are moving through more than one cell during transmission.
In a cellular network, as the distributed mobile transceivers or mobile phones move from cell to
cell during an ongoing continuous communication, switching from one cell frequency to a
different cell frequency is done electronically without interruption and without a base station
operator or manual switching. This is called handover or handoff. The base station is responsible
for monitoring the level of the signals when a call is made from a mobile phone. When the user
moves away from the geographical coverage area (cell) of the base station, the signal level may
fall, this may result to interrupting the call. Handover therefore occurs when the base station
makes a request to the mobile switching center (MSC) to transfer the control (the ongoing call

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and the mobile phone in use) to another base station that is receiving the strongest signals
without notifying the subscriber (Janssen 2014).
Generally, a mobile network is made up of base transceiver station (BTS), mobile switching
center (MSC), location registers and public switched telephone network (PSTN). The BTS
enables cellular devices to make direct communication with mobile phones. The mobile phone
acts as a base station to route calls to the destination base center controller. The base station
controller (BSC) coordinates with the MSC to interface with the landline-based PSTN, visitor
location register (VLR) and home location register (HLR) to route calls toward different base
center controllers (Janssen 2014).
In the case of cellular networks, the data is transmitted not to a central hub in a small network of
devices (as it is with Wi-Fi) or even directly from device to device (as it is with Bluetooth), but
through a global network of transmitters and receivers as seen above (Miller 2013).
A typical cellular network can be envisioned as a mesh of hexagonal cells, as shown in figure 2
below, each with its own base station at the center. The cells slightly overlap at the edges to
ensure a successful and unnoticeable handover.

Figure 2: Cells in a cellular or mobile network

The base station at the center of each group of cells functions as the hub for those cells, not of
the entire network, but of that individual piece of the network (Miller 2013).

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Radio frequency signals are transmitted by an individual phone and received by the base station,
where they are then re-transmitted from the base station to another mobile phone. Transmitting
and receiving are done over two slightly different frequencies.
Base stations are connected to one another via mobile switching centers which track calls and
transfer them from one base station to another as callers move between cells. Each base station is
also connected to the main telephone network, and can thus relay mobile calls to landline phones
(Miller 2013).
A mobile network is used by the mobile phone operator to achieve both coverage and capacity
for their subscribers. In cities, each cell site may have a range of up to approximately ½ mile
(0.80km), while in rural areas; the range could be as much as 5 miles (8.0km). It is possible that
in clear open areas, a user may receive signals from a cell site 25miles (40km) away (Wikipedia
2014).
In summary, a mobile network is a network of radio base stations forming the base station
subsystem. The core circuit switched network serves for handling voice calls and text messages.
A packet switched network for handling mobile data and the public switched telephone network
to connect subscribers to the wider telephony network (Wikipedia 2014).

2.3.1 Features of a Mobile Network

 The main feature of a mobile network is the ability to re-use frequencies to increase both
coverage and capacity. Mobile phones transmit at a very low power of about 0.6watt to
3watt signals, unlike a radio station that transmits at about 50000watt signal. They get by
with such low power transmission because they transmit within a relatively limited range;
network cell. The low power transmission does not allow the mobile phone’s signal to
extend beyond the current cell, and this way the same frequency can be used by multiple
cells without danger of interference. The elements that determine frequency re-use are the
re-use distance and the re-use factor (Miller 2013).
 Larger coverage area than a single terrestrial transmitter, since additional cell towers can
be added indefinitely and are not limited by the horizon.
 Mobile networks maintain information for tracking the location of their subscribers’
mobile devices. In response, mobile devices are also equipped with the details of
appropriate channels for signals from the mobile network systems.

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 These channels are categorized into two fields:
 Strong Dedicated Control Channel: Used to transmit digital information
to a mobile phone from base station and vice versa.
 Strong Paging Channel: Used for tracking the mobile phone by a mobile
switching center, when a call is routed to it (Janssen 2014).
 They give subscribers advanced features over alternative solutions, including increased
capacity, small battery power usage, a larger geographical coverage area and reduced
interference from other signals.

2.3.2 Mobile Network Operators (MNO)

A Mobile Network Operator also known as mobile network carrier and wireless service provider
e.t.c. is a telecommunications service provider organization that provides wireless voice and data
communication for its subscribed mobile users. They are independent communication service
providers that own or control the complete telecom infrastructure (radio spectrum allocation,
wireless network infrastructure, back haul infrastructure, billing, customer care, provisioning
computer systems e.t.c.) for hosting and managing mobile communications between the
subscribed mobile users and users in the same and external wireless and wired telecom networks
(Janssen 2014).
A key defining characteristic of a mobile network operator is that an MNO must own or control
access to a radio spectrum license from a regulatory or government entity. A second key defining
characteristic of an MNO is that an MNO must own or control the elements of the network
infrastructure necessary to provide services to subscribers over the licensed spectrum (Wikipedia
2014). Mobile network operators create a network of high-end telecommunication devices,
specialized software and client-end subscriber identity modules to provide end-to-end
communication between wired and wireless telecom end-users devices (Janssen 2014).
Mobile network operators install a number of base stations, while mobile subscribers use a
circuit-like chip in their mobile phones to access network services when they are in the range or
coverage cell of a base station. Besides providing voice dialing and receiving capabilities, MNOs
also provide data communication through text messages and internet connectivity and are now
providing video communications as well (Janssen 2014).

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Generally, mobile network operators make use of mobile networks to offer wide network
coverage to their subscribers. Some good examples of MNOs include: AT&T, T-Mobile,
Verizon Wireless, AIRTEL, MTN, ETISALAT, and GLO.

2.4 MOBILE TECHNOLOGY

Mobile technology is simply the technology that is used for cellular communication. They can be
in the form of mobile IT devices which include: laptops and net book computers, palm top
computers or personal digital assistants (PDA), mobile phones and smart phones, global
positioning system (GPS) devices and wireless debit/credit card payment terminals e.t.c.
But there are the mobile technologies that power the mobile networks, classified or known as
mobile telecommunication technology. The mobile devices listed above connect to the mobile
telecommunication technologies to participate in a mobile network. Some mobile
communication technologies include: wireless fidelity (Wi-Fi) - a type of wireless local area
network technology, Bluetooth – which connects to mobile devices wirelessly, third generation
(3G), fourth generation (4G), global system for mobile communication (GSM) and general
packet radio service (GPRS) data services – data networking services for mobile phones, dial-up
services – data networking services using modems and telephone lines and virtual private
networks – secure access to a private network. The 3G and the 4G network will be discussed in
details.

2.4.1 3G Technology

The term 3G refers to the third generation of mobile phone standards, as set by the International
Telecommunications Union (ITU). It is the third type of access technology that has been made
widely commercially available for connecting mobile phones (Thomas 2014).
The first generation of mobile phones was launched in the 1980’s and transmitted across with
analogue signal; these phones were large, brick-like devices that were often kept in a vehicle as
they were impractical and inconvenient to carry around.
They were supplanted by the second generation in the 1990’s, which now used a more reliable
digital signal, and enabled the use of text messaging, or SMS (short message service). However,

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the technology was still not robust or fast enough to deal with the thousands, and then millions of
consumers who wanted to use mobile phones; the signal could not carry enough data
simultaneously, and there were many areas the signal did not cover. There was also a rapidly
growing demand for transmitting data – using email and accessing the internet across mobiles,
which 2G was just not fast or reliable enough to manage. An intermediate technology known as
EDGE or 2.5G came next, but the technology rapidly moved on towards proper 3G (Thomas
2014).
The development of 3G services in the early years of the 21 st century was a major step forward
both in terms of reliability and coverage for voice calls and text messaging, as well as providing
far more rapid access to the internet due to its capability of carrying larger amounts of data. In
theory, the service should allow users the capacity to an amount of data equal to a song per
minute, but in reality, actual experienced speeds are likely to be some what less than this.
The introduction of widespread 3G led to the adoption of the term “mobile broadband”, as this
was the first time it became a realistic option whilst on the move; for example, on a bus as a
passenger (Thomas 2014).
The 3G services work using a cellular-based technology; the signals are passed from base station
to base station, and then the base station nearest to the phone passes the signal to it. The base
stations ensure that a wide spread strong and reliable signal is available. It also means there can
be dips in service as you move around, as the signal switches from base station to base station.
3G comes with a lot of added functions which include the broadband, and it is also possible to
use mobile broadband through 3G on other devices such as laptop computers, by using a small
pencil-sized device known as dongle (also known as USB modem), which is simply slotted into
one of the USB ports on the side of the PC to give access on the move. 3G broadband simply
implies that 3G enables devices such as mobile phones and dongles to browse the internet, check
emails and download files, music and video clips where ever there is coverage (Thomas 2014).
3G is made possible by two complementary technologies – HSDPA (high speed download
packet access) and HSUPA (high speed upload packet access respectively. These technologies
enable mobile broadband users to access download speeds of up to 21mb and upload speeds of
up to 1.76mb via a mobile dongle, mobile phone e.t.c. (Thomas 2014)
Predecessors of 3G such as 2G and GPRS offered limited internet connectivity that was often
costly and slow. Conversely, because 3G uses the air waves more efficiently, it can offer greater

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speeds and flexibility at a very cheap rate. The relationship between 2G and 3G is similar to that
of dial-up and broadband, or terrestrial TV and digital TV. In all, the later examples, greater
spectral efficiency has enabled more consumer choice and a more effective service. Simply put,
more data is transmitted faster.
Whilst 3G is quite effective when it comes to giving users mobile access to the internet, and is a
vast improvement of the previous 2G technology, it is still far from perfect. Download speeds
can sometimes be slower than expected with the signal strength very variable, and coverage
below 100%, as coverage fade in and out as you move around. However, the technology
continues to improve rapidly, with phone manufacturers producing phones with faster
processors, and mobile operators also upgrading their networks. The High Speed Packet Access
plus (HSPA+) also known as 3.5G, which has a faster speed of up to 42Mbps, twice that of
HSPA has also helped to improve network speeds (Thomas 2014).

2.4.2 4G Technology

4G is the name given to fourth generation of mobile networks, just as the previous generation is
called 3G. Another thing that is seen tagged onto the end of 4G is “LTE”, which stands for Long
Term Evolution and is a type of 4G technology. 4G LTE aims to offer users faster, more reliable
broadband internet for devices like smart phones, tablets and laptops (Martin 2012).
Loosely speaking, 4G is around five times faster than existing 3G services. Theoretically, it can
provide download speeds up to 100mbps, but it cannot be achieved in reality.
4G technology does not work in already existing smart phones, it functions with newer smart
phones like the Samsung Galaxy S3 LTE (not the regular S3) or one of the other brand new 4G-
capable smart phones. This is because the 4G networks use different frequencies to data than 3G,
and only the mobile phones that have a modem to support these new frequencies can operate on
the network (Martin 2012).
Although 4G is a new technology, it has actually been around for many years. Two forms of 4G
have been developed and are in use: WiMAX and LTE. WiMAX was launched by South Korean
firm in 2006, have been in use at sprint, across the Atlantic in US in 2008 and was trialed in UK
in 2009. The first LTE was deployed in Scandinavia in 2009, but it was debatable whether the
speeds on offer back then were really 4G or not (Martin 2012).

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4G’s headline download speed is 100mps and a blistering 50Mbps for upload. This makes 4G
more than twice as fast as the latest 3G technology and many more times faster than previous
versions. Of course these speeds are theoretical, and such speeds won’t be reached in reality.
However, that doesn’t mean that 4G isn’t twice as fast. The faster speeds mean websites load
quicker, and that videos and podcasts will be streamed without first waiting for them to buffer. It
addition, large email attachments or other content from the web will be downloaded faster.
Applications which need to download data, such as maps, will work more smoothly, especially
when zooming in or out as this generally requires a lot of data. The speed differential should be
akin to switching from 3G to Wi-Fi (Martin 2012).
For video streaming and similar tasks, where Wi-Fi would be typically required for smooth
performance, 4G should allow for a ‘home broadband’ experience on the move. EE (Everything
Everywhere, which is the name of the firm that tested the 4G network in UK), expects the
average speed to be between 8 and 1212Mbps, potentially faster than the 5.9Mbps average for
ADSL home broadband. 4G also provides faster upload speeds, for example, pictures would be
posted to Facebook or Twitter very quickly (Martin 2014).
The main reason why 4G is faster than 3G is because of the Orthogonal Frequency-Division
Multiplexing (OFDM). It is the same technology used in Wi-Fi, ADSL broadband, digital TV
and radio. ODFM is a technique for squeezing more data onto the same amount of radio
frequency. It also reduces latency and interference. Data is split up and sent via small chunks of
frequency in parallel, therefore increasing the capacity of the network (Martin 2012).
Multiple-input and multiple-output (MIMO) is another reason why 4g is able to provide faster
speeds. It is simply the use of multiple antenna arrays at both the transmitter and receiver to
improve communication performance. This allows more data to be transferred without requiring
additional bandwidth or drawing more power. The most common configuration currently is a 2x2
MIMO, found in many smart phones and some tablets. A 4x4 setup is also possible and promises
even faster speeds but is still a little way of making its way onto devices. Since different setups
are possible, one phone could provide faster 4G speeds than another (Martin 2012).
With 3G phones, there is the ‘data roaming’ function which enables one to pick up emails and
browse websites as soon they enter another country. But with 4G, things are different. Although
there are 4G networks in many countries around the world, the Nigerian 4G smart phone won’t
necessarily work everywhere. This is because 4G doesn’t operate on the same frequencies in

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every country. If your phone’s 4G modem doesn’t work on the same frequencies as those used in
the country you are visiting, then you will have to do with 3G instead. Even if the numbers do
match, there needs to be a 4G roaming agreement between operators. Currently, such agreement
doesn’t exist, and when they do, the data prices are going to be very expensive (Martin 2012).

Technology Frequency Spectrum (UK)

3G 850MHz 900MHz 1900MHz 2100MHz
4G 800MHz 1800MHz 2600MHZ
Wi-Fi 2400MHz 5000MHz
Bluetooth 2400MHz

2.5 JAMMING TECHNIQUES

Ahmed (2006) stated that there are several ways to jam a mobile set, and went further to explain
the three most common ways/techniques of jamming a mobile phone as follows:

 SPOOFING: In this kind of jamming, the device forces the mobile phone to turn off
itself. This type is very difficult to be implemented since the jamming device first detects
any mobile phone in a specific area, then the device sends the signal to disable the mobile
phone. Some types of this technique can detect if a nearby mobile phone is there and
sends a message to tell the user to activate silent mode or switch the phone off. These
types of jamming devices are known as Intelligent Beacon Disablers.

 SHIELDING ATTACKS: This is known as TEMPEST or EMF shielding. This kind

requires closing an area in a faraday cage so that any device inside this cage cannot
transmit or receive RF signal from outside of the cage. This area can be as large as
buildings, for example: banks, schools, worship centers e.t.c. This type is usually very
expensive and prohibitive because to shield power-frequency AC magnetic field is next
to impossible, hence, not the best of ideas.

17
  DENIAL OF SERVICE: This technique is referred to DOS. In this technique, the
device transmits a noise signal at the same operating frequency of the mobile phone in
order to decrease the signal-to-noise ratio (SNR) of the mobile phone under its minimum
value. This kind of jamming technique is the simplest one since the device is always on.
The jammer being developed in this project is of this type.

2.6 WIRELESS SIGNAL JAMMER

Apart from mobile phones, it is also possible for a jammer to interfere with wireless technologies
like Bluetooth and Wi-Fi, e.t.c.
According to (Wikipedia 2014), Wireless Signal Jammers are devices used to interrupt radio
signals. They are most often used to interfere with wireless local area network (WLAN).
Advanced and expensive versions are used to jam satellite communications. The wireless signal
jammer can be used to temporarily stop transmission in any unit that receives electrical signal for
operation like the radios, televisions, and microwave e.t.c. Jamming can be categorized into two
namely:
 Obvious Jamming, which is easy to detect, and manifests as some type of noise such as:
random noise, stepped tones, spark, gulls, random pulse, wobble, recorded sounds and
preamble jamming.
 Subtle Jamming, which is not obvious, which no sound is heard on the receiving
equipment. The unit doesn’t receive incoming signals, yet everything seems normal to the
operator. It manifests as “squelch capture”.
According to Milt (2010), it is possible to have a jammer that can jam Wi-Fi and Bluetooth
signals at once. This jammer was presented in his website (www.jammerfromchina.com). It was
also stated that Wi-Fi and Bluetooth technologies support exchanging data within short distances
by using the 2.4G frequency band for the convenience of those who need to use them for transfer
of information and files. Also, Wi-Fi is cheaper for big businesses since it can connect several
systems to one connection. However, there are some problems encountered, like the possibility
of a hacker hacking into your privacy of classified documents because of their poor abilities to
work against hackers. Also on the other hand, the ability of tracking your location is another
problem. With these in view, a jammer that jams wireless signals is most likely the best chance
at removing the potential dangers.
18
Also, a Wireless Spy Camera Jammer that can protect your privacy from spying cameras
working via wireless video, wireless LAN and Bluetooth bands is possible and even available.
According to Vondracek (2014), the frequency range covered by the jammer is between 900MHz
to 2.5GHz, covering all video cameras mentioned and also effective for Bluetooth and Wi-Fi. It
was also stated that business men or individuals who do not want their meetings recorded, as
well as their activities in hotel rooms, dressing rooms, and rest rooms e.t.c. recorded without
their consent, has this jammer as the perfect device. Once it is turned on, you can have peace of
mind conducting your presentations, meeting and legal proceedings e.t.c. The device also has a
“hidden camera detector” function, which locates and disables cameras if you prefer the service.

2.7 MOBILE JAMMING REQUIREMENTS

Husin (2010), jamming objective is to inject an interference signal into the communications
frequency so that the actual signal is completely submerged by the interference. It is important to
notice that transmission can never be totally jammed - jamming hinders the reception at the other
end. The problem here for the jammer is that only transmitters can be found using direction
finding and the location of the target must be a specific location, usually where the jammer is
located and this is because the jamming power is never infinite. Jamming is successful when the
jamming signal denies the usability of the communications transmission. In digital
communications, the usability is denied when the error rate of the transmission cannot be
compensated by error correction. Usually a successful jamming attack requires that the jammer
apower is roughly equal to signal power at the receiver. The effects of jamming depend on the
jamming-to-signal ratio (J/S), modulation scheme, channel coding and interleaving of the target
system. Generally Jamming-to-Signal ratio can be measured according to the following
Equation:

J = Pj Gjr Grj R2tr Lr Br

S Pt Gtr Grt R2jr Lj Bj where:

Pj= jammer power Pt= transmitter power

Gjr= antenna gain from jammer to receiver

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Grj= antenna gain from receiver to Jammer
Gtr= antenna gain from transmitter to receiver
Grt= antenna gain from receiver to transmitter
Br= communications receiver bandwidth
Bj= jamming transmitter bandwidth
Rtr= range between communications transmitter and receiver
Rjt= range between jammer and communications receiver
Lj= jammer signal loss (including polarization mismatch)
Lr= communication signal loss
The above equation indicates that the jammer Effective Radiated Power, which is the product of
antenna gain and output power, should be high if jamming efficiency is required. On the other
hand, in order to prevent jamming, the antenna gain toward the communication partner should be
as high as possible while the gain towards the jammer should be as small as possible. As the
equation shows, the antenna pattern, the relation between the azimuth and the gain, is a very
important aspect in jamming.
Also as we know from Microwave and shown in the equation distance has a strong influence on
the signal loss. If the distance between jammer and receiver is doubled, the jammer has to
quadruple its output in order for the jamming to have the same effect. It must also be noted here
the jammer path loss is often different from the communications path loss; hence gives jammer
an advantage over communication transmitters (Husin 2010).

2.8 MOBILE JAMMING TECHNOLOGY

Alkan (2012) stated in his work that the technologies behind mobile jamming include:
 Overpowering the mobile phone signals
 Decreasing the SNR for mobile communication.
Overpowering the mobile phone signal simply implies transmitting a signal at a very high
frequency that equates the frequency of the mobile phone, thereby colliding with the frequency
of the phone, and cancelling out each other. While
Decreasing signal-to-noise-ratio (SNR) is the process of deactivating communication by match-
making the mobile signal (meaningful information) and the transmitted signal (noise), resulting
to loss of communication or network.
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 CHAPTER THREE
METHODOLOGY AND SYSTEM ANALYSIS

3.1 INTRODUCTION

Methodology is seen as a very important aspect of project writing because it provides a detailed
explanation on the procedures to be used in carrying out the research (Abdul 2004). This chapter
briefly summarizes the whole idea of methodology and the types of methodology in existence, it
will also talk about data collection methods and fact findings, indicating each one used in the
research. This chapter also covers the analysis of the existing system, and provides justification
for the new system.

3.2 METHODOLOGY

Methodology is the systematic, theoretical analysis of the methods applied to a field of study, or
the theoretical analysis of the body of methods and principles associated with a branch of
knowledge. Methodology does not set out to provide solutions but offers the theoretical
foundation or support for understanding which method, set of methods or so called “best
practices” can be applied to a specific case (Wikipedia 2014).
It is also defined in the thesaurus dictionary as a set or system of methods, principles, and rules
for regulating a given discipline, as in the arts of sciences.

3.2.1 Types of Methodology

 Object Oriented Methodology: this is a system development approach that encourages

and facilitates re-use of software components. With this methodology in view, a
computer system can be developed on a component basis which enables the effective re-
use of existing components and facilitates the sharing of its components by other systems.
The object oriented methodology simply emphasizes modularity and re-usability, and its
goal is to satisfy the open closed principle. A module is open if it supports extension; that
is, it provides standardized ways to add new behaviors or describe new states. In the

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 object-oriented methodology, this is often accomplished by creating a new subclass of an
existing class. A module is closed if it has a well defined stable interface that all other
modules must use and that limits the interaction and potential errors that can be
introduced into one module by changes in another. In the object oriented methodology,
this is accomplished by defining methods that invoke services on objects. Methods can be
either public or private, i.e. certain behaviors that are unique to the object are not exposed
to other objects. This reduces a source of many common errors in computer
programming. (Wikipedia 2014)

 Waterfall Methodology :this type of methodology is a sequential design process used in

software development processes, in which progress is seen as flowing steadily
downwards (like a waterfall) through the phases of conception, initiation, analysis,
design, construction, testing, implementation and maintenance. This is practically a
hardware methodology, but because no software development methodologies existed at
the time, it was simply adapted for software development. (Wikipedia 2014)

 Prototyping Methodology: this is a software development process which allows

developers to create portions of the solutions to demonstrate functionality and make
needed refinements before developing the final solution. (Bowman 2009). The
methodology works very well with online transaction processing systems, which usually
interact. It also works well with web-based development and can very quickly help
confirm page navigation and other user interaction requirements. It is very useful for
confirming business intelligence analytic requirements, because end users do not usually
think in terms of facts and dimensions, and they are frequently not exposed to the
capabilities of business intelligence software and the power of the tools. (Bowman 2009).
The basic premise of prototyping is the software should not be used for production, and
the technique can save considerable development time by reducing re-work as users see
the product for the first time. (Bowman 2009).

 Descriptive or Qualitative: this type of research methodology involves describing in

details specific situations using research tools like interviews, surveys and observations.

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 The approach adopted by qualitative researchers tends to be inductive which means that
they develop a theory or looks for a pattern of meaning on the basis of the data collected.
It involves a move from specific to the general and it’s sometimes called a bottom-up
approach (Alzheimer 2013).

 Descriptive or Quantitative: this type of research methods requires quantifiable data

involving numerical and statistical explanations. It usually involves collecting and
converting data into numerical form, so that statistical calculations can be made and
conclusions drawn. The quantitative researchers will have one or more hypotheses
(questions to be addressed which include predictions about possible relationships
between the things to be investigated). In order to find answers to these questions, the
researchers will also have various instruments and materials and a clearly defined plan of
action (Alzheimer 2013). Quantitative analysis hinges on researchers understanding the
assumptions inherent within different statistical models.

3.2.2 Choice of Methodology

In this research work, more than one choice of methodology was used. The main or major
methodology type used is the Waterfall Methodology. It involves a sequential down flow of the
design process, from the conception phase to the implementation phase. Another methodology
used in this project is the object oriented methodology, which involves the effective re-use of
existing components to design a new system. Though the object oriented methodology is a
software development methodology, which implies software components, it also applies to this
project.

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3.3 DATA COLLECTION AND FACT FINDING

Data collection is the process of gathering and measuring information on variables of interest, in
an established systematic fashion that enables one to answer stated research questions, to test
hypothesis and to evaluate outcomes. Data collection is common to all fields of study, including
physical and social sciences, humanities, business e.t.c. while the methods of data collection vary
by discipline. Fact finding on the other hand, refers to identifying the facts that are essential to
the research from the collected data (Wikipedia 2014).

3.3.1 Methods of Data Collection

The methods of data collection are as follows:

 QUESTIONNAIRE
This consists of set questions submitted to a number of persons known as respondents, used for
collecting a relevant data in a study. It sets out to gather factual information in an enquiry form
through which respondents answer questions or responds to statements in writing.
Questionnaire can be categorized as Close/Structured and Open/Unstructured.
When structured/closed, respondents are provided with alternative answers from which they will
select one or more answers depending on the way the question was structured. On the other hand,
they are unstructured or open-ended when they require free responses in the respondents’ words
and style. This type is designed to permit free responses from participants rather than those
limited to specific alternatives. It is common to find both the structured and the unstructured
designs in one questionnaire, each with its set objectives (Abdul 2004).
One of the advantages of questionnaire is that it can be sent to a large number of people, which
saves time and money. Also, people are more truthful while responding to the questionnaires
regarding controversial issues, due to the fact that their responses are anonymous. One of the
disadvantages is that majority of the people who receive questionnaires don’t return them, and
those who do might not be representative of the originally selected sample (Abdul 2004).
Questionnaires often make use checklist and rating scales, which helps to simplify and quantify
people’s behaviors and attitudes. A checklist is a list of behaviors, characteristics or other entities
being sought for while a rating scale is more useful when a behavior needs to be evaluated.

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  INTERVIEW
The interview method is similar to questionnaire in a number of ways, to the extent it has been
described as an oral questionnaire since the respondent/interviewee does not have to give written
responses. By its nature, interview allows for the collection of first-hand data as well as for a
greater depth of response from the respondent. Like the questionnaire, interviews are of two
categories namely Structured/Close and Unstructured/Open.
When the questions o be asked at the interview session have been listed in what is called an
Interview Schedule, such is considered as being structured. In that case, the interviewer will be
guided by the questions listed in the schedules as he adheres strictly to them.
On the other hand, an unstructured interview is open-ended and allows for freedom of both
questions and answers. It is more flexible than the structured one as further probing questions not
listed in the Interview Schedule could be asked (Abdul 2004).
Interviews could be done fact-to-face, which enables the interviewer to establish rapport with
potential participants, and therefore gain their cooperation. It could also be done via telephone
(telephone interview), which is less time consuming and less expensive.
Another form of interview is the computer assisted personal interview, which involves the
interviewer bringing a laptop or hand-held computer to enter the information directly into a
database. This method saves time involved in processing the data, as well as saving the
interviewer from carrying around hundreds of questionnaires (Abdul 2004).

 OBSERVATION
Observation is used for the purpose of collecting data, and it can be used virtually in all research
situations. It is categorized into two namely: participant and non-participant.
In the former, the researcher is directly involved in the data collection exercise through
observation, while in the latter, the researcher does not directly participate in the exercise.
Participant Observation is usually structured while the Non-participant is unstructured (Abdul
2004). Observation is often used as a data collection method, to complement the use of other
methods. In that case, it is used to cross-validate certain responses from the either the
questionnaire or the interview. For Observation to be effective, the observer should record his
observation on the spot and have a good safekeeping of record of their observations.

25
The most convenient way of using observation as a tool for data collection is to have a checklist.
A checklist is a list of all possible behaviors, for example behaviors that could occur during a
particular event/phenomenon being investigated. Against each item in such a list, the observer
scores or rates their observations (Abdul 2004).
In recording observations, it is important that it does not distract or create a barrier between the
observer and those being observed.

 DOCUMENTARY SOURCES
This method of data collection is not common in research/project, it is very important only when
experimentation is not possible (Abdul 2004). Documentary Sources are categorized into
primary and secondary sources, where the primary sources consists of original materials such as
official or personal documents; which are records containing first hand information like
eyewitness accounts, personal papers, archival records, local government publications,
autobiographies and memoirs, collected speeches and contemporary articles.
On the other hand, secondary sources are records or accounts prepared by someone else other
than the person or persons who were participants/observers of an event. They consist of
testimonies of individuals who were not eyewitnesses, but who prepared records of the events for
one reason or the other. Examples here include news, stories, and feature articles in news paper
and periodicals, written accounts of related events like committee meetings, hearings, board
deliberations, dedication ceremonies, memorials e.t.c. particularly when they were written by
participants in the activities.

In this project, the Observation method of data collection was used, and also, the Documentary
Sources was used. The project was compiled and written from the combination of materials, both
the ones containing first hand information (primary sources) and otherwise (secondary sources)
as describe lastly in this section, and also from the combination of direct and indirect
Observations.

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3.4 ANALYSIS OF EXISTING SYSTEM

A mobile network jammer simply transmits a high frequency signal that cancels out one of the
mobile phone signals, thereby deactivating the mobile phone as earlier stated. As easy and
straight forward this function may seem there are also complex and more sophisticated devices
that have been produced just for the same purpose of deactivating a mobile phone. In order to
properly analyze and understand the various kinds of jamming devices already in existence, their
capabilities and their level of sophistication, they will be grouped into types, and described
chronologically.

3.4.1 Type "A" Device: JAMMERS

In this device, mobile phone signals are overpowered by a stronger signal. It comes equipped
with several independent oscillators transmitting jamming signals capable of blocking
frequencies used by paging devices as well as those used by cellular/PCS systems control
channels for call establishment.
When active in a designated area, such devices will (by means of RF interference) prevent all
pagers and mobile phones located in that area from receiving and transmitting calls. This type of
device transmits only a jamming signal and has very poor frequency selectivity, which leads to
interference with a larger amount of communication spectrum than it was originally intended to
target. Technologist Jim Mahan said, “There are two types. One is called brute force jamming,
which just blocks everything. The problem is, it’s like power-washing the airwaves and it bleeds
over into the public broadcast area. The other puts out a small amount of interference, and you
could potentially confine it within a single cell block. You could use lots of little pockets of
small jamming to keep a facility under control.” (Husin 2010)

3.4.2 Type “B” Device: INTELLIGENT CELLULAR DISABLERS

Unlike jammers, Type “B” devices do not transmit an interfering signal on the control channels.
The device when located in a designated (quiet) area, functions as a detector. It has a unique
identification number for communicating with the cellular base station. When a Type “B” device
detects the presence of a mobile phone in the quiet room; the filtering (i.e. the prevention of
authorization of call establishment) is done by the software at the base station.

27
When the base station sends the signaling transmission to a target user, the device after detecting
simultaneously the presence of that signal and the presence of the target user, signals the base
station that the target user is in a quiet room; therefore, do not establish the communication.
Messages can be routed to the user’s voice- mail box, if the user subscribes to a voice-mail
service. This process of detection and interruption of call establishment is done during the
interval normally reserved for signaling and handshaking. For emergency users, the intelligent
detector device makes provisions for designated users who have emergency status.
These users must pre-register their phone numbers with the service providers. When an incoming
call arrives, the detector recognizes that number and therefore allows the call to be established
for a specified maximum duration, say two minutes. The emergency users are also allowed to
make out going calls. Similarly, the system is capable of recognizing and allowing all emergency
calls routed to “911”. It should be noted that the Type “B” detector device being an integral part
of the cellular/PCS systems, would need to be provisioned by the cellular/PCS service providers
or provisioned by a third-party working cooperatively with full support of the cellular/PCS
service providers (Husin 2010).

3.4.3 Type “C” Device: INTELLIGENT BEACON DISABLERS

Unlike jammers, Type “C” devices do not transmit an interfering signal on the control channels.
The device, when located in a designated quiet area, functions as a beacon, and any compatible
terminal is instructed to disable its ringer or disable its operation, while within the coverage area
of the beacon. Only terminals which have a compatible receiver would respond and this would
typically be built on a separate technology from cellular/PCS, e.g. wireless, paging, ISM and
Bluetooth. On leaving the coverage area of the beacon, the handset must re-enable its normal
function.
This technology does not cause interference and does not require any changes to existing
PCS/cellular operators. The technology does require intelligent handsets with a separate receiver
for the beacon system from the cellular/PCS receiver. It will not prevent normal operation for
incompatible legacy terminals within a “quiet” coverage area, thus effective deployment will be
problematic for many years. While general uninformed users would lose functionality, pre-
designated “emergency” users could be informed of a “bypass terminal key sequence” to inhibit
response to the beacon. Assuming the beacon system uses a technology with its own license (or

28
in the license exempt band), no change to the regulations are needed to deploy such a system.
With this system, it would be extremely difficult to police misuse of the “bypass key sequence”
by users (Husin 2010).

3.4.4 Type “D” Device: DIRECT RECEIVE AND TRANSMIT JAMMERS

This jammer behaves like a small, independent and portable base station, which can directly
interact intelligently or unintelligently with the operation of the local mobile phone. The jammer
is predominantly in receiving mode and will intelligently choose to interact and block the cell
phone directly if it is within close proximity of the jammer.
This selective jamming technique uses a discriminating receiver to target the jamming
transmitter. The benefit of such targeting selectivity is much less electromagnetic pollution in
terms of raw power transmitted and frequency spectrum from the jammer, and therefore much
less disruptive to passing traffic. The jam signal would only stay on as long as the mobile
continues to make a link with the base station; otherwise there would be no jamming
transmission – the technique forces the link to break or unhook and then it retreats to a passive
receive mode again.
This technique could be implemented without cooperation from PCS/cellular providers, but
could negatively impact PCS/cellular system operation. This technique has an added advantage
over Type B in that no added overhead time or effort is spent negotiating with the cellular
network. As well as Type B, this device could discriminate 911 calls and allow for
breakthroughs” during emergencies (Husin 2010).

3.4.5 Type “E” Device: EMI SHIELD - PASSIVE JAMMING

This technique involves using EMI suppression techniques to make a room into what is called a
Faraday cage. Although labor intensive to construct, the Faraday cage essentially blocks, or
greatly attenuates, virtually all electromagnetic radiation from entering or leaving the cage or in
this case a target room. With current advances in EMI shielding techniques and commercially
available products one could conceivably implement this into the architecture of newly designed
buildings for so-called “quiet-conference” rooms. Emergency calls would be blocked unless
there was a way to receive and decode the 911 transmissions, pass by coax outside the room and
re-transmitted. This passive configuration is currently legal in Canada for any commercial or

29
residential location insofar as DOC Industry Canada is concerned, however municipal or
provincial building code by- laws may or may not allow this type of construction (Husin 2010).

3.4.6 Problems of Existing System

Existing mobile phone jammers as have been successfully and effectively deployed, still have
some identifiable problems as concerned within the locality of Nigeria. Some of the identified set
backs are as follows:
 They operate at a very high frequency, hence jamming mobile phones within 200 meters
distance or more, and areas in Nigeria where the devices could be deployed are not as
large as 200 meters, therefore, the jammer tends to interfere with mobile phones outside
the range of the jamming area.
 In as much as existing jammers operate at high frequencies of over 1000Mhz, and with
such frequencies generated, the four major network providers in Nigeria can be
deactivated, a jammer still has to be specially designed for the purpose of effectively and
solely deactivating signals from these four major network providers. Such jammers are
not available.
 Most of the jammers in use were not built with the correct specification, for instance, a
jammer with a circuit that should be powered by a 3 volt battery, using about a 6 volt
battery instead, which is above the required specification and therefore may cause the AC
and the DC to be transmitted together in the air, instead of only the AC being transmitted.
This can interfere with the jamming process or even cause more complication.
 Jamming devices are forbidden in many countries, Nigeria inclusive. The prohibition in
the use of these devices has made it difficult to actually understand all the defects in the
functioning of the devices, as it is not constantly in use, and when used, it is done so
under ‘hiding’. Except therefore in cases where they are used under the permission of the
law.

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3.5 JUSTIFICATION FOR THE NEW SYSTEM

For every new system, it is expected that it should have a contribution to the area in which it is to
be deployed, which should further solve a problem or problems in the designated area. This
contribution no matter how little forms the basis to justify the proposed system. The mobile
phone jammer being developed in this project has also tried to meet this expectation. Although
existing jammers has seemingly incorporated all the functions a jammer can execute, making
room for little or no added function, a jamming device could also be designed and packaged to
be deployed in a specific location, with a different or the same requirements from other jammers,
just to be able to satisfy or solve the jamming needs that is peculiar to that location, which other
jammers may not specifically solve. The justification for this new system is that it generates an
average frequency of about 450 MHz, which jams mobile phones within 100 meters around the
jamming areas, and can hardly interfere with mobile phones outside this range. Also, it will
successfully jam network signals from the four main mobile network providers in Nigeria
namely: MTN, GLO, ETISALAT and AIRTEL. It is designed with the correct specification and
everything in the circuit is working at average, thereby promoting accuracy, efficiency and
throughput.
Finally, in Nigeria today where there are so many scenarios of bomb explosions, it is believed
that some of these bombs are detonated using GSM frequency, and the Nigerian government will
be ready to adopt any solution even if it means legalizing a jamming device. With the device in
view, it can be implanted in places where there are crowd, to disrupt the GSM frequency there
incase a bomb working with GSM signal is to go off unnoticed. Also, jammers are now
becoming common electronic devices with the rate of increasing developments, and sooner than
later, it will be legalized all over, thereby grabbing a place in the future of ICT.

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 CHAPTER FOUR
SYSTEM DESIGN AND IMPLEMENTATION

4.1 INTRODUCTION
The designing phase of this project commenced with the identification of the components,
understanding the relationship between the components and understanding the circuit entirely.
When these components were identified and bought, they were carefully assembled on a Vero
board and soldered appropriately and accordingly with a soldering iron and LED. This took place
during the implementation stage of the project. After the components were assembled and
arranged, the new system was tested on some mobile phones to try getting a result. This chapter
deals with the circuits; the properties of the electronic components as well as the entire system
design features, the implementation and the testing.

4.2 DESIGN OBJECIVES AND CONSIDERATIONS

A mobile network jammer as earlier described is a device that transmits signal at the same
frequency at which mobile phones operate. When this happens, the signal being transmitted from
the device collides with the signal coming from the base station to the mobile phones, since they
are of the same frequency. When they collide, the two frequencies are cancelled out and mobile
phones are deactivated.
The objective for developing this device however is to properly deactivate mobile phones in
areas where they are not needed, to disable only the mobile phones only in such specified areas
without interfering with phones outside the range and disabling phones that operate only with the
four main network providers in Nigeria as has been mentioned above.

In order to effectively achieve this design, two major factors were considered:
1. The voltage that is supplied into the circuit as soon as it is turned ON, which is
immediately stored by the capacitor. The supply of voltage has to be average because
excess supply of voltage may not be contained in the capacitor, and minimal supply may
delay the jamming process. Therefore 3volts is supplied immediately the device is

32
 powered, and it’s further stored by a 15 Pico Farad capacitor in value. This voltage is
supplied by combining two finger batteries with the value of 1.5v each.
2. The frequency generating process which involves the capacitor (which stores the supplied
voltage) and an inductor. The values of these two components which form the tuning
circuit are very important as it determines how effective the jamming process will be and
also the distance of the jamming process, to make sure it covers the specified area totally
and that it doesn’t exceed. The value of the inductor is supposed to be 22nH, but due to
the difficulty in reading inductor values, the value ranges between 22 and 120. The
capacitor value is 15pf. Also, during course of the project, it was discovered that a
trimmer capacitor which generates different values as it communicates with the inductor,
thereby making the jammer dynamic was preferable.

4.3 CIRCUITRY DESIGN AND ANALYSIS

The circuit of any device determines the working of that device, because it is the blue print of
such device, and as so describes the laying out of the device. If something goes wrong in a
device, for instance, the device fails to work after construction; the best point of solution will be
the circuit diagram. Also adjustments and improvements to a system are also made from the
circuit diagram. This section is intended to describe the circuits that make up the jammer circuit,
explain the relationships between them and how they communicate with each other. It also
explains the configuration of the circuit to provide a better understanding of the circuit by
identifying and listing the components. This chapter also briefly describes these components and
how they communicate with each other and the entire system as a whole. The circuit diagram of
the jammer is shown in figure 3 below.

33
 Figure 3: Mobile Network Jammer Circuit

From the above circuit diagram, which represents the system diagram, there are three main
circuits, which are combined to form the jammer circuit just like any jammer. They include:
 RF (radio frequency) amplifier circuit
 Voltage Controlled Oscillator circuit
 Tuning circuit.

4.3.1 RF Amplifier Circuit

This circuit comprises of the transistor Q1, capacitors C4 and C5 and resistor R2. Their main
function is to amplify the signal generated by the tuned circuit. The amplification signal is given
to the antenna through capacitor C6.

34
4.3.2 Voltage Controlled Oscillator Circuit
This circuit represents the process of the tuning circuit; the tuning circuit becomes tuned by
controlling the voltage supplied into the circuit. Basically, when the transistor Q1 is turned ON,
the tuned circuit at the collector will get turned ON. The tuned circuit will act as an oscillator
with zero resistance. The oscillator or tuned circuit will produce the very high frequency with
minimum damping. The both inductor and capacitor of the tuned circuit will oscillate at its
resonating frequency. Therefore the voltage controlled oscillator circuit comprises of the tuned
circuit, transistor T1 and capacitors C2 and C3.

4.3.3 Tuning Circuit

The tuning circuit consists of capacitor C1 and inductor L1. When the circuit is turned on, the
voltage is stored by the capacitor according to its capacity. The main function of the capacitor is
to store electric energy. Once the capacitor is completely charged, it will allow the charge to flow
through the inductor. The inductor on the other and is used to store magnetic energy. When the
current is flowing across the inductor, it will store the magnetic energy by this voltage across the
capacitor and the capacitor decreases. At some point complete magnetic energy is stored by the
inductor and the charge or voltage across the capacitor becomes zero. The magnetic charge
through the inductor will be decreased and the current will charge the capacitor in opposite or
reverse polarity manner. Again, after some period of time, the capacitor will get completely
charged and magnetic energy across the inductor will be completely zero. Again capacitor will
give charge to the inductor and becomes zero. After some time, inductor will give charge to the
capacitor and become zero and they will oscillate (become tuned) and generate the frequency.
This circle run up till the internal resistance is generated and oscillations will get stopped.
Generally, the RF amplifier feed is given through the capacitor C5 to the collector terminal
before C6 for gain or like a boost signal to the tuned circuit signal. The capacitors C2 and C3
will generate the electronic pulses (technically called noise) for the frequency generated by the
tuned circuit. The feedback boost given by the RF amplifier, frequency generated by the tuned
circuit and the noise generated by capacitors C2 and C3 will be combined, amplified and
transmitted to the air through the antenna.

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4.3.4 Components list

Component Name Component No Value

Resistor R1 100R
Resistor R2 39k
Capacitor C1 15pf
Capacitor C2 4.7pf
Capacitor C3 4.7pf
Capacitor C4 102pf
Capacitor C5 1MF
Capacitor C6 2.2pf
Capacitor C7 103pf
Transistor Q1 BF494
Inductor L1 22nH
Antenna 800MHz

4.4 COMPONENT DESCRITPION

This section briefly describes each of the components listed above as represented in the circuit,
their functions and how they communicate with each other to achieve successful jamming.

4.4.1 Resistor 100R (ohms)

Resistors generally act to reduce current flow, and at the same time to lower voltage levels
within circuits. The resistor 100R is directly connected to the emitter of the transistor and then
goes to the ground. Therefore this resistor which is shown in figure 4 below is the load resistor
(emitter loading) which loads the emitter by limiting the maximum current flowing through the
voltage controlled oscillator circuit which is connected to the collector terminal of the transistor.
This function can also be achieved by the 100k (kilo ohms) resistor.

Figure 4: 100R reisitor

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4.4.2 Resistor 39k (kilo ohms)
This resistor makes its connection directly from the power and then to the base of the transistor.
It serves the same purpose of reducing the voltage in the circuit. It reduces the voltage that is
supplied to the tuning circuit and also serves as base resistor (base biasing) which again limits
the maximum transistor’s base current. It is clearly shown in figure 5 below:

Figure 5: 39k resistor

4.4.3 Capacitor 15pf (Pico Farad)

The general function of a capacitor is to store electric current or charge. They are of different
types; paper capacitors, ceramic capacitors, electrolytic capacitors, trimmer capacitors and
variable capacitors e.t.c. This particular capacitor, a ceramic capacitor is a major component of
the jammer device. It generates the frequency needed, together with the inductor which will be
described later. It stores the supplied voltage to the circuit as electric energy until it is fully
charged, after which it allows the charge flow through the inductor. When this process executes
repeatedly, frequency will be generated. A trimmer capacitor is the best alternative for this
function. It is shown in figure 6 below:

Figure 6: 15 Pico Farad capacitor

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4.4.4 Capacitor 4.7pf (Pico Farad)
This capacitor seen as the feedback capacitor appears twice in the circuit, and they are
interconnected to work together to generate the noise signal which is sent out along with the
generated freqeuncy from the tuned circuit and boosted signal from the RF amplifier circuit.
They are ceramic capacitors as shown shown in figure 7 below and they store the current
received from the emmiter of the transistor which is used to generate the noise signal. The
capacitor used for this function has a value of 5pf.

Figure 7: 4.7 Pico Farad capacitor

4.4.5 Capacitor 102 pf (Pico Farad)

This capacitor is responsible for reducing the generaed noise in the circuit. It is interconnected
from the power line to the feed boost line which is connected at the base of the transistor. It
stores part of the voltage supplied from the power line and utilizes t in the reduction of noise. It
is clearly shown in figure 8 below:

Figure 8: 102 Pico Farad capacitor

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4.4.6 Capacitor 1MF (Micro Farad)
This is an electrolytic capacitor that is responsible for boosting the signal from the tuned circuit
at the RF amplifier circuit. After boosting the signal, it is passed on (feed back) to the transistor
along with the generated frequency and noise. It is clearly shown in figure 9 below:

Figure 9: 1 micro farad capacitor

4.4.7 Capacitor 2.2pf (Pico Farad)

This is a ceramic capacitor that collects all generated signals and frequency and sends it to the
antenna. It also removes the DC signal and allows only the AC (generated) signal to be
transmitted to the air. It is at the edge of the circuit to determine and kind of filter what goes to
the air. It is shown in figure 10 below:

Figure 10: 2.2 Pico Farad capacitor

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4.4.8 Capacitor 103 pf (Pico Farad)
This capacitor is connected from the power line down to the ground. It is responsible for
generating the AC signal . It stores some of the voltage supplied when the circuit is powered and
utilizes it in its function. It is clearly shown in figure 11 below:

Figure 11: 103 Pico Farad capacitor

4.4.9 Transistor BF 494

A transistor is generally used to amplify and switch electronic signals and electrical power. It is
made uo of three terminals; the collector, the base and the emitter. When voltage is applied to
one terminal, it changes in other terminals. Transistors are always in two different
configurations: PNP (Positive-Negative-Positive) and NPN (Negative-Positive-Negative). The
PNP sinks current into its base while the NPN sources current through its base. But the main
difference between the two is that holes are the more important carriers for the PNP while
electrons are more important carriers for the NPN transistors. The BF 494 transistor that is used
in this circuit is a PNP transistor as shown in figure 12 below. It is responsible for the
amplification of the feedback boost given by the RF amplifier, frequency generated by the tuned
circuit and noise signals generated by the two noise generating capacitors. After amplification, it
passes it on to the antenna.

Figure 12: BF 494 transistor

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4.4.10 Inductor 22nH (nano Henry)
An inductor, also called a coil or reactor is a passive two terminal electrical component which
resists changes in electric current passing through it. It consists of a conductor such as wire,
usually wound into a coil. When current flows through it, energy is stored temporarily in a
magnetic field in the coil. When the current flowing through an inductor changes, the time-
varying magnetic field induces a voltage in the conductor which opposes the change in current
that creates it (Faraday’s law of eletromagnetic induction). Inductors can be used for so many
purposes including frequency generating. The inductor being described here is a frequency
generating inductor with a value of 22nH as shown in figure 13 below:

Figure 13: 22nH inductor

However, it is usually very difficult to know the value of an inductor due to its coil nature and
also, it is almost impossile to find 22nH inductor. The inductor used in this project ranges from
22 to 120, the specific value is not known. An inductor when connected to a capacitor generates
frequency, which is the function of the inductor in the circuit. The inductors used in this project
even during the test-run are 3 coils, 4 coils inductors that are also used in receiving FM signals
as shown in figure 14 below. Their values are not known, but the required frequency is generated
anyway.

Figure 14: frequency generating inductors

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4.4.11 Antenna
An antenna or aerial is an electrical device which converts electric power into radio waves and
vice versa. It is usually used with a radio transmitter or a radio receiver. In transmission , a radio
transmitter supplies an electric current oscillating at radio frequency (i.e. a high frequency
alternating current (AC)) to the antenna’s terminals, and the antenna radiates the energy from the
current as electromagnetic waves (radio waves). In reception, an antenna intercepts some of the
power of an electromagnetic wave in order to produce a tiny voltage at its terminals, that is
applied to a receiver to be amplified. The antenna used in this project was used for transmission
purpose. Actually, it receives the amplified signals from the transistor and the AC signal and
sends them out to the air.

4.4.12 Battery
An electric battery is a device consisting of one or more electrochemical cells that converts
stored chemical energy into electrical energy. Each cell contains a positive terminal known as
cathode and a negative terminal known as anode. Electrolytes allow ions to move between the
electrodes and terminals, which allows current to flow out of the battery and perform work. The
circuit makes use of 3volts battery which is shown in figure 15 below. Each time the circuit is
powered, 3 volts flows in to it.

Figure 15: Collection of 3 volts batteries

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4.5 SYSTEM IMPLEMENTATION

Most hardware systems under go four main phases of existence which include concept,
specification, designing and implementation. Having discussed the concept behind the project,
the specification and the designing, the implementation phase which seems like the main process
in this project will however be examined in this section in detail. The implementation phase
generally describes how the designed system was made to be functional. The implementation of
this project was not a difficult one because from understanding the circuit, all you have to do is
to solder the components to one another on a Vero board, according the configuration on the
circuit. The implementation however took the following sequence.

4.5.1 Implementation of the RF Amplifier Circuit

The components that make up this circuit were identified;they include the resistors, the transistor
and the C4 and C5 capacitors as stated earlier in section 4.2.1. The transistor was duely observed
so as to determine the collector, base and emitter to ensure proper conection. This is because,
according to the circuit diagram, only the base and the emitter are connected to the RF amplifier
circuit, the collector went to the tuning circuit. And if the connections are wrongly made, the
emitter would not be able to do the work of the collector, which will result to system failure.
Firstly, the capacitor C7 was soldered to the vero board and connected to the ground before the
other components of the circuit were soldered.accordingly.

4.5.2 Implementation of the Tuned circuit and the VCO circuit

These two circuits were implemented together because of their relationship. All their
components were identified and soldered to the board in line with the configuration of the circuit.

4.5.3 Final Implementation and Assembly

After all the components were soldered to the Vero board by the use of LED wire, the antenna
was connected accordingly, then the excess wire from the already soldered components were cut
off. This is because in a high frequency circuit, excess wire which conducts electricity, can cause
conductance in the circuit which is unnecessary and can alter the jamming process. Finally, a
battery cage was wired at the top of the tuning circuit, and then a power button was connected to
the battery.

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 CHAPTER FIVE
SYSTEM TESTING, INTEGRATION AND DEPLOYMENT

5.1 SYSTEM TESING AND INTEGRATION

After the construction and implementation phase, the system built has to be tested for
Durability, Efficiency, and Effectiveness and also ascertain if there is need to modify this
construction.The system testing process began before the implementation, where some
components were tested, and also after the implementation where the system was tested as a
whole. The testing took the following sequence.

5.1.1 Component Testing

The testing of the components were done before the implementation of the system, but not all the
components were tested due to lack of instrument of testing. The resistor components of the
circuit were the only ones to be tested to ensure their values were correct, by the use of a
galvanometer. This was because, the galvanometer could not be utilized in measuring other
components of the system.

5.1.2 Test Plan

After the implementation of a system, there will be a test plan that will effectively check out the
working of the system and to ensure everything is in order. The test plan makes it possible for
corrections to be made where needed, even after implementation. The test plan here was to insert
a 3volts battery, since the circuit is powered by 3 volts, turn the power on and see the result of
the jammer on the mobile phones around.

5.1.3 Final Test Result

When the jammer device was turned on, it deactivated the mobile phones within the environ. It
also deactivated mobile phones powered by MTN, AIRTEL, GLO and ETISALAT network
providers as shown in figures 16, 17, 18 and 19, and the jamming was effective only within the
regulated area, as mobile phones outside the area were functioning. The jammer met the
specifications correctly, except that the jamming frequency exceeded the actual value (450MHz)

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and the jamming distance exceeded a little above 100meters. This was because the specified
value of the inductor was not used as a result of unavailability. A coil of higher value was used
instead. This project successfully achieved its aim.

Figure 16: MTN powered mobile phone screen showing when jammer was off (from the
left) and when jammer was turned on (from the right).

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Figure 17:AIRTEL powered mobile phone screen showing when jammer was off (from the
left) and when jammer was turned on (from the right).

Figure 18:GLO powered mobile phone screen showing when jammer was off (from the left)
and when jammer was turned on (from the right).

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Figure 19:ETISALAT powered mobile phone screen showing when jammer was off (from
the left) and when jammer was turned on (from the right).

The actual testing process is not just to block the transmission signal but also to check the
duration of the time taken by the device to block the transmission between the four operators.
From the testing results, the time taken for the device to block these four mobile network
operators was totally different. The power of the operator at the mobile phone is different which
makes the duration time taken to block the transmission also different. ETISALAT operator has
the closest power to the device which makes it to be blocked faster than others as shown below:

Operators Duration (seconds)

MTN 80
AIRTEL 93
GLO 89
ETISALAT 58

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5.2 SYSTEM DEPLOYMENT

There are so many areas to which a mobile network jammer could be deployed to solve the
problem of mobile phone. Some of these areas already been mentioned during the project will be
fully described as follows;
This jamming device can be deployed in areas where necessary, like churches, banks, conference
halls, filling stations and library e.t.c. where the use of mobile phone is prohibited.
It can also be deployed in exam halls, to disconect any one attempting to use a mobile phone for
malpractice purposes. It wouldn’t just be necessary to search every examination candidate and
possibly harass them prior to the exam and even during the exam, just activate the jammer device
and allow it to take care of the defaulters, and possibly expose them as they may be struggling to
get signal on the phone and unconciously forget they are in the exam hall due to the frustration
caused by the jammer.
The mobile network jammer can most importantly be deployed in crowded areas, due to the fact
that crowded areas are a major threat to Nigerians because bombs blasts occurs in crowded areas.
The good news is that many of the bombs are detonated using mobile signals or radio frequency,
and the jammer interrupts such signals.

5.3 DEVICE PACKAGING

On completion of the system testing, the device was wired on a small plastic casing, that looks
like a mobile phone as shown in figure 20 below. The measurements of the casing is not known
and also the components are not much.

Figure 20: Mobile Jammer Casing

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 CHAPTER SIX
SUMMARY, CONCLUSION AND RECOMMENDATIONS

6.1 SUMMARY OF ACHIEVMENTS

With a little more stress of soldering the components together, many of the components were
assembled according to the circuitry design on paper. At the end, a functional circuit was
produced. It was functional because the specifications were correctly implemented. It was not so
easy a task, getting to identify the entire components after mixing them up in leather. Sorting
them out was a problem, but it was successfully sorted out and put in place.
Finally, this project was an eye opener to electronics and network design. Although courses that
covers the subjects were made available, but they were not detailed enough or practicalized due
to the fact that we are computer science students and not computer engineering students.

6.1.1 Problems or Limitations

During the construction stage of this project, many problems were encountered, especially
during the specification and the implementation phase of the project.these problems are
discussed below.
 Component Problems
This is the major problem faced in this project, because most of the components are very difficult
to see. As a matter of a fact, only few of the components were implemented with the correct
specification because the correct specifications for most of them are usually unavailable. For
instance, the actual height of frequency being generated is not known, because the specified
inductor cannot be seen. Most other components are highly expensive.
 Technical Problems
The jammer in this project can only jam one of the links of the mobile phone, precisely the one
cuming from the base station to the phones. With this in view, smart phones with high frequency
operation tend to bypass the jammer. The means of jamming the both signals of the mobile
phone is a problem that could not be handled in this project.
Soldering the components to the board accurately was also another problem encounterd in this
project.

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Generally, the use of mobile network jammer is prohibited in nigeria and many other countries,
making it impossible to really deploy the device.
Apart from these few problems, the project was a huge success.

6.2 CONCLUSION

It is evident from the results that the designed mobile network jammer disabled the mobile
phones that were used for the purpose of testing the device, thus achieving its aim. It also
blocked the transmission from the four main mobile network operators in Nigeria which are
MTN, AIRTEL, ETISALAT and GLO. The costruction of the Mobile Network Jammer
successfully achieved the entire objectives targeted.
Even though this is an illegal device, it is also very useful to achieve some certain goals as duely
explained in this project. The jamming technique utilized in this project is the denial os service
commonly known as DOS, which involves transmitting a noise signal at the same operating
frequency of the mobile phones inorder to decrease the signa-to-noise ratio (SNR) of the mobile
phone under its minimum value. Jamming devices would be of more advantage than
disadvantage if made legal. This is because the advantages are very as has been discussed in the
project; it can be used in any place at all to ensure silence and orderliness, to prevent malpractice
in exams through the use of mobile phones and to prevent the detonation of bombs. However,
jammers are designed according to locattion, even though it can jam network anywhere. For
instance, a jammer designed to jam cell phones in a bank at china, may not be used for the same
purpose in a bank at nigeria. This is because, the bank in china maybe bigger, which will make
the jammer to interfere with mobile phones outside the bank. And also the bank in china maybe
smaller in radius, which will make the jammer to jam just some parts of the bank in nigeria.
Jammers must be built according to location, so that the distance to be jammed can be properly
specified Though jammers were initially used by the army, infact, the main concept behind the
development of the device at first, was for the benefit of the army during the time of war, to
deactivate communication, it only had to take a little adjustment to improve upon the device to
work on mobile phones and therefore made it a civillian device.

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6.3 RECOMMENDATIONS

This project is sort of a stepping stone to what jammers can be used to achieve, and therefore is
open to further adjustments and improvements. There are a few improvements that should be
made for the device to be more stable. Firstly, the main subject is the frequency generation. The
frequency generated can be improved by using a high frequency VCO and power amplifier or by
doing the frequency calculation using the frequency formular to increase the value of frequency
generating capacitor and inductor. Secondly, the jamming radius can be wider. It will be nice to
disconect a whole city from using mobile phones during a time of crises, if the situation calls for
it. To improve the radius, a more stable power supply should be designed for robust operation of
the device. The antenna also must be a bit bigger for the sake of power transfer.
I also recommend the integration of micro controllers and sensors in jammers, so that the
jamming process could take place when situations that requires it arises. For instance, a jammer
installed in a particular place can remain inactive, but programmed to activate itself when the
crowd accumulates to a certain number.
With these improvements and adjustments subject to jammers, they could be very useful devices
in ICT future, even though they are old devices, they could be grabbing a place in the future of
ICT.
I also recommend the proper study of electronics with hundred percent practicals, so that future
computer scientists can decipher and resolve devices of this kind and other electronic devices.

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