MOBILE PHONE JAMMER DESIGN

Prepared for

Dr. M. K. Satyarthi

Project supervisor

Training and Placement OfficerUSICT, GGSIP University

Prepared by

Subodh Kumar Sharma08116412812

Vipin Kumar07616412812

The Department of Electronic and Communication Engineering

USICT, GGSIP University

GGSIP University, Electronic and Communication Engineering Department

Acknowledgement

I would like to offer my special and endless thanks to my supervisor Dr. M. K. Satyarthi,Training and Placement Officer, USICT,GGSIP University for his help, guidance, support and encourage throughout

my study.

i

TABLE OF CONTENTS

1. INTRODUCTION 1

1.1.Background & Problem ..................................................... …....11.2.Purpose ………………………………………………………..11.3.Significance ……………………………………………………11.4.Scope …………………………………………………….........11.5.Sources & Methods ……………………………………………..11.6.Summary ……………………………………………………...21.7.Organization …………………………………………………....2

2. DISCUSSION of FINDINGS 3

2.1.Stages of the project…………………………………………..…….........3 2.1.1.The first stage of the project-Phase 1……… ……….….............3 2.1.1.1.Researching Literature …………………………………..3 2.1.1.2.Determining Operational Parameters ……………….........4

a 1) Frequency band………………………………….4

b 1) Distance to be jammed……………………………5

c 1) Free Space Loss(Path Loss) (F)…………………….5

2.1.1.3.Power Calculation…………….……………………….5

2.1.2. The second stage of the Project-Phase 2…………………….. 9

2.1.2.1.Determining the compatibility of the theory and practice…….9

2.1.2.2.Determining the design components……………………..10

a 2) THE IF SECTION…………………………….. 11

b 2) THE RF SECTION ……………………………..13

2.1.2.3.Assembling the mobile phone jammer for 900 MHz network...14

2.1.2.4.Conducting tests……………………………………...14

ii

3. CONCLUSIONS ………………………………………………………………144. COST OF THE DEVICE……………………………………………………...15

5.WHAT CAN BE DONE MORE?..........................................................15

REFERENCES ………………………………………………………...16

iii

1.INTRODUCTION

1.1.Background & Problem

We have experienced a boom in the number of mobile phone users in recent years. This has

caused the need of a more efficient and controllable signal transmission in some environment such as

library, hospital or conference room where silence is required.For this aim, the usage of mobile

phone jammers have been growed up. Mobile phone jammer is a transmitter that disrupts the

communication between base stations and mobile phones. Today, mobile jammer devices are

becoming civilian products rather than electronic warfare devices.

1.2.Purpose

In this project, we attempted the design and development of mobile phone jammer for GSM

900. We aimed to determine system parameters, make power calculations for device, and compare

our parameters and power calculations with the reality. Additionally, we planed to establish system

desing and assemble a device and lastly conduct some tests.

1.3.Significance

Designing mobile phone jammer is a hard issue in Turkey. In literature, we can not find

almost no study related to this topic. So, if we achieve to design a jammer at the end of this project,

this will make an important contribution to the people wanting to study on this topic.

1.4.Scope

In this project, we worked on one of the networks to jam, not on all networks. GSM 900 was

dealt with, but not GSM 1800 or CDMA 1900.

1.5.Sources & Methods

While dealing with this project, primary and secondary sources were used. Some research

was done and studies and analysis on this topic were obtained. Later, as a primary source, some

experiments were carried out and lastly a hardware design was implemented.

1

1.6.Summary

At the end of the project, we could achieve to assemble a mobile phone jammer for 900

MHz network.

1.7.Organization

In this report, firstly the stages of the project are mentioned. The all process is analysed in

detailed.In the following parts, the results obtained by the end of the project and the cost information

are mentioned respectively. In the last part, how the project can be improved is debated.

2

2. DISCUSSION of FINDINGS

Mobile jammer is a device which disturbs the communication between the mobile base station

and mobile equipment by transmitting the noise signal at the frequency, on which both are trying to

communicate with each other. Firstly, jammers were invented to prevent the communication between

the army personnels of enemy and in time they developed into civilian life. The technology behind

the mobile jammer is overpowering the mobile phone signals and decreasing the SNR( Signal to

Noise Ratio)for mobile communication.

2.1.Stages of the Project

Our project mainly consists of two different stages, Stage 1 and Stage 2.

2.1.1.The first stage of the project- Phase 1

Stage 1 is the part of that I tried to understand the logic and working principle

behind a mobile phone jammer. For this reason, this part consists of researching literature as a first

step and determining the operational parameters as a second step. Lastly, in the framework of this

data, some power calculations have been carried out.

2.1.1.1. Researching Literature

Five types of devices are known to have been developed (or being

considered for development) for preventing mobile phones’ communications in certain specified

locations.

Type‘A’Devices: ‘jammers’. It contains several independent oscillators transmitting

‘jamming signals’ that block frequencies used by mobile communication devices for call establishment.

3

Type ‘B’ Devices: ‘intelligent cellular disablers’. The device normally works as a detector. When it

detects signaling from the base station to the mobile station, it signals the base station not to establish

communication. This process of detection and interruption of call establishment is done during the

interval normally reserved for signaling and handshaking. Type‘C’Devices: ‘intelligent beacon disablers’. These devices act as ‘beacons’, i.e. they instruct

any mobile device within their area of coverage to disable its ringer or disable its operation. The

problem is that these types of devices require intelligent handsets.

Type ‘D’ Devices: ‘Direct Receive and Transmit Jammers’. They behave as a small independent

base station. 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.

Type “E” Devices: ‘EMI Shield – Passive Jamming’. This technique uses Electromagnetic

Interference (EMI) suppression techniques to construct what is called a Faraday cage. The Faraday

cage essentially blocks all electromagnetic radiation from entering or leaving the cage.

The technique we will use in our project is the first one called ‘ Denial of Service’

2.1.1.2.Determining Operational Parameters

We needed to determine some parameters which affect the performance of

a mobile jammer. These parameters can be categorized into 3 groups.

a 1) Frequency band

Frequency band is an important factor for us, since we first of all need to decide on

which frequency we will transmit our jamming signal. In mobile communication, there is

a technology called FDD (Frequency Division Duplexing). This means that for a network,

one part of the frequency band is allocated to uplink signals (from mobile phone to the

base station), another part is allocated to downlink signals (from base station to the

mobile phone). Thanks to this technology, we can talk and listen simultaneously on the

phone. In our project, we jammed downlink band since we are so remote from base

4

station generally. This means that it is so much easy to jam the signals from base station

to the mobile phone. These bands work out at 935-960 for GSM 900.

b 1) Distance to be jammed

As the distance increases, the total power we need to jam a mobile phone increases

proportionally.

c 1) Free Space Loss(Path Loss) (F)

As our jamming signal travels through the air, it will attenuate. There are some factors

affecting the magnitude of FSL. These factors can be seen in the calculation formula of

FSL.

F(dB)=32.44+20log(distance in km)+20log(frequency in MHz)

Derivation of Free Space Loss formula

FSL= (4∗π∗d)/λ)2 = (4∗π∗d∗f)/c)2

λ=Signal wavelength (in meters)

f=Signal frequency (in Hertz)

d=Distance from the transmitter (in meters)

c=Speed of light in vacuum (in meters/second) c=3*108

FSL(dB)=10*log10(4∗π∗d∗f)/c)2 = 20*log10(4∗π∗d∗f)/c)

( in our calculation; d is in km and f is in MHz)

FSL(dB)=20*log10(d)+20*log10(f)+20*log10(4∗π∗103∗106 /c )

2.1.1.3.Power Calculation

After determining the design parameters, we needed to know how much

power approximately we will need to achieve jamming.

5

As a jamming signal, we needed a signal that its frequeny spectrum can cover

all frequencies in a specific range. A White Gaussian Noise can model this in a best way.

( Figure1: Noise Power Spectral Density)

W

Pn =∫Sn(f)df= No*W (Noise Power in a restricted bandwidth)

-w

(Signal to noise ratio) SNR= €s/No, €s/T = Ps, 1/T ≈ W ( €s: Energy of

message signal, W: Bandwidth)

SNR=Ps/Pn (Ps=signal power, Pn=noise power)

SNR=Ps/Pn=(€s∗W)/(N0∗W)=Ps/(N0∗W) No=k*T at T=2930K,

k=1.38*10-23 J/K (k:Boltzman Constant) No≈ 4*10-21 J

SNR(max)=30 dB for GSM

30 dB=10*log10(Ps/Pn) Ps=Pn*1000 (Pn= No*W)6

Ps/W=No*1000 (Watt/Hz) (Signal Power Density)

No*1000=Signal Power Density=Interference Signal Power Density

In GSM network,

The spectrum is divided into 200 kHz channels.(FDMA)

The hopping sequence may use up to 64 different carrier frequencies

(frequency hopping )

So, Hopping Bandwith=64*200 kHz=12.8 Mhz

(Figure2: Noise Spectral Density in a Restricted Bandwith)

According to this;

Interference Signal Power=No*1000*64*200kHz(W)=5.12*10-11 (W)

For GSM 900 network;

7

(Figure3: Power Spectral Density of Message Signal in GSM 900)

In all 935-960 Mhz band; to jam max.100 m distance:

Interference Signal Power=No*1000*25 Mhz=10-10(W)= -70dBm

FSL(dB)=20log(0.1)+20log(960)+32.44=72.04 dB

Total power from jammer= -70 dBm + 72.04 dB= 2.04 dBm

= 1.5 mW

This calculations are so rough, because we did not take the multi fading, reflection-refraction

effects into account.

8

2.1.2.The second stage of the Project-Phase 2

we determined the compatibility of the theory and practice, determined the

design components of mobile phone jammer, established the system design, and trying to

implement the hardware configuration. assembled a device for 900 MHz networks and will

conducte some test.

2.1.2.2.Determining the design components

(Figure 6: Block Diagram of a Mobile Phone Jammer)

10

a 2) THE IF SECTION

The IF design of the mobile phone jammer just consists of a Triangle Wave

Generator. (to tune the VCO in the RF section)

a 2-1) Triangle Wave Generator

The cheapest and easiest way of producing a triangle wave is to use a 555 timer in

astable vibration mode. A schematic of 555 timer can be seen in the following figure.

(Figure 7: Schematic of 555 Timer)

(Figure 8: 555 Timer)11

.

(Figure 9: 555 Timer in Astable Vibration Mode)

( Figure 10: Pin Connection of 555 Timer in Astable Mode)

Initially, when the power is turned on, the capacitor C is uncharged and thus the trigger voltage at

pin 2 is 0 V. This causes the output of the lower comprator to be high and the output of the upper

comprator to be low, forcing the output of the flip flop, and thus the base of discharge transistor low

12

and keeping the transistor off. Then, C begins charging through Ra and Rb (Figure 9). When the

capacitor voltage reaches to Vcc/3, the lower comprator switches to its low ouput state, and when the

capacitor voltage reaches to 2Vcc/3, the upper comprator switches to its high output state. This sets

the flip flop high output and transistor on. Now, the capacitor discharges through R2 and discharge

transistor. When it discharges to Vcc/3, the lower comprator switches to high, and the output

becomes zero and transistor off. And this process repeats itselfs. So, we can get a triangle wave from

the pin 2.

In our project, we needed a duty cycle, meaning that charging time equals with the discharging time.

For this aim, we simply connected a diode parellel with Rb and also Ra must be equal to Rb.

Oscillation frequency (f)= 1.44/(Ra+Rb)*C

b 2) THE RF SECTION

The RF part consists of

Voltage Controlled Oscillator

Power Amplifier

( Figure 11.Complete Block Diagram of 900 MHz Mobile Phone Jammer)

13

2.1.2.3.Assembling the mobile phone jammer for 900 MHz network

(Figure 12.Printed Circuit Board of 900 MHz Jammer)

2.1.2.4.Conducting tests

3. CONCLUSIONS

.

15

4. COST OF THE DEVICE

Circuit elements(555 timer,capacitors,resistors) ~ 250 Rs.

VCO ~ 115 Rs.

Power Amplifier: provided from cell phone

The cost of the PCB ~ 800 Rs.

Total cost = ~ 1200 Rs.

5.WHAT CAN BE DONE MORE?

Our device is cumbersome .It is just transmitting a jamming signal in all 900 MHz downlink

frequency band.Using an FPGA card,device performance can be increased.Additionaly,instead of

transmitting power in all freqency band,a ‘smart jammer’ which transmits according to frequency

usage of user can be designed for the power saving .

REFERENCES

1) Boylestad, Rober L. & Nashelsky, Louis,Electronic Devices and Circuit Theory, 9th Ed., Prentice

Hall,2006

2) Mishra, N.K.; , ”Development of GSM - 900 Mobile Jammer: An approach to overcome existing

limitation of jammer”, Wireless Communication and Sensor Networks (WCSN), 2009 Fifth IEEE

Conference on , pp.1-4, 15-19 Dec. 2009

3) Shah, S.W.; Babar, M.I.; Arbab, M.N.; Yahya, K.M.; Ahmad, G.; Adnan, T.; Masood, A.; , ”Cell phone

jammer,” Multitopic Conference, 2008. INMIC 2008. IEEE International, pp.579-580, 23-24 Dec. 2008

4) Proakis, John G., Digital Communications, 4th Ed., McGraw-Hill, 2001

16

GLOSSARY OF TERMS

Signal to Noise Ratio (SNR): In analog and digital communications, signal-to-noise ratio, often written S/N or

SNR, is a measure of signal strength relative to background noise. 

Fading: In wireless and mobie communication systems, signal is attenuated by the propagation

media and this affect is called fading.

Free Space Loss: The free space path loss, also known as FSPL is the loss in signal strength that occurs

when an electromagnetic wave travels over a line of sight path in free space. 

IF: In communications and electronic engineering, an intermediate frequency (IF) is a frequency to which

a carrier frequency is shifted as an intermediate step in transmission or reception.

RF: Radio frequency (RF) is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to

the frequency of radio waves, and the alternating currents which carry radio signals.