15-10-2012, 01:20 PM
Jammer for Mobile Phone Systems
Jammer for Mobile Phone.pdf (Size: 110.38 KB / Downloads: 53)
Abstract
This paper presents the design, implementation, and
testing of a dual-band cell-phone jammer. This A Jammer for
Mobile Phone Systems works at GSM 900 and DSC 1800
simultaneously and thus jams the three operator in Thailand :
AIS,DTAC and TRUE MOVE. This project follow in studying
the GSM-system to find the best jamming technique, establishing
the system design and selecting suitable components. After that
drawing the overall schematics, fabricating the PCB layout,
assembling the devices, performing some measurements and
finally testing the mobile jammer.
The designed a jammer for mobile phone systems was
successful in jamming the three operator in Thailand could meet
the aim set.
INTRODUCTION
A Jammer for Mobile Phone Systems is a device which
transmits noise-induced signals at the same frequencies at
which a GSM system operates, thus rendering mobile phones
in the specified area unusable.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. Cell phones are
designed to add power if they experience lowlevel
interference, so the jammer must recognize and match the
power increase from the phone. Cell phones are full-duplex
devices, which means they use two separate frequencies, one
for talking and one for listening simultaneously. Some
jammers block only one of the frequencies used by cell
phones, which has the effect of blocking both. The phone is
tricked into thinking there is no service because it can receive
only one of the frequencies. Less complex devices block only
one group of 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. Some of the high-end
devices block all frequencies at once, and others can be tuned
to specific frequencies. To jam a cell phone, all you need is a
device that broadcasts on the correct frequencies.
The Control-section
The tuning section of the jammer sweeps the VCO through
the desired range of frequencies. Basically, it is just a triangle
or sawtooth-wave generator, offset at a proper amount so as
to sweep the VCO from the minimum desired frequency to a
maximum. The tuning signal is generated by a triangular
wave mixed with noise. The Control section consists of three
main parts:
Triangle wave generator. (To tune the VCO in the RF section.
Noise generator (provides the output noise).
Mixer “summer” (to mix the triangle and the noise waves).
CONCLUSION
The jamming device was successfully designed and
subsequently constructed with similar success. The device
was tested against all cellular carriers currently operating on
the GSM band in Thailand, including: AIS,DTAC and TRUE
MOVE. The range varied from 12m to up to 30m