This document discusses mobile phone jammers. It begins with an introduction to what a mobile jammer is and its history of use by law enforcement. It then describes four types of jamming techniques - Type A jammers, Type B intelligent cellular disablers, Type C intelligent beacon disablers, and Type D direct receive and transmit jammers. The document outlines the design and components of jammers, and lists some applications such as use in schools, prisons, hospitals and for security purposes. It concludes by noting both positive and negative aspects of jammer technology.
2. What is mobile jammer?
History
How is works?
Types of jamming techniques?
Design parameter and specification
Block diagram
Types and application
Future scope
conclusion
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3. A mobile phone jammer is an instrument used to
prevent cellular phones from receiving signals from
base stations.
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4. Mobile jammer was originally developed for law
enforcement and the military to interrupt
communications by criminals and terrorists.
Some were also designed to foil the use of certain
remotely detonated explosives.
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5. Transmits same radio frequencies of greater power as the cell
phone, disrupting the communication between the phone
and the cell-phone base station in the tower.
This causes interference with
communication of cell phones
and towers to render the phones
unusable. On most phones,
the network would be out of
range.
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6. Type "A" Device: JAMMERS
Type “B” Device: INTELLIGENT CELLULAR DISABLERS
Type “C” Device: INTELLIGENT BEACON DISABLERS
Type “D” Device: DIRECT RECEIVE & TRANSMIT JAMMERS
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7. 1.Type "A" Device: JAMMERS
This type of device comes equipped with several
independent oscillators transmitting ‘jamming
signals’ capable of blocking frequencies used by
cellular systems for call establishment.
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8. 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 ’quite’ area, functions as a ’detector’.
When the device detects the presence of a mobile phone in
the "silent" room; a prevention of authorization of call
establishment is done by the software at the base station.
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9. 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
operation, while within the coverage area of beacon.
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10. 4. Type “D” Device : DIRECT RECEIVE & TRANSMIT JAMMERS
This jammer behaves like a small, independent and portable
base station, which can directly interact with the operation of
the local mobile phone. The jammer is predominantly in
receive mode and will intelligently choose to interact and
block the cell Phone directly if it is within close proximity of
the jammer.
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11. The frequency band GSM 900 (935-960 MHz )
GSM 1800 (1805-1880 MHz)
The distance to be jammed (R)
Jamming–to-signal ratio
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13. Adjustable Mobile Jammer
School &Prison Mobile Jammer
Remote Control Mobile jammer
Explosion – Proof Mobile jammer
Police & Military Mobile Jammer
Portable Mobile Jammer
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15. To maintain the complete silence in library and
lecture hall.
To avoid fraud in examination hall.
To avoid disturbance in class room.
For providing security in business conference, board
of directors rooms, seminars, etc.
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17. While the law clearly prohibits using a device to
actively disrupt a cell-phone signal, there are no
rules against passive cell-phone blocking.
Companies are working on devices that control a cell
phone but do not jam the signal.
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18. Every technology has good aspect as well as bad
aspect, the important thing is, how we are using it.
Cell phone jammers are very useful to the society
from the anti-social elements.
Cell phone jammers prevent the students from using
cell phones to the schools and colleges.
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The frequency bands UPLINK (Handset transmit) DOWNLINK(Handset receive) GSM 900: 890-915 MHz 935-960 MHz GSM 1800 1710-1785 MHz 1805-1880 MHz Jamming frequency must be the same as the downlink, because it needs lower power to do jamming than the uplink range and there is no need to jam the base station itself. So, our frequency design will be as follows: GSM 900 935-960 MHz GSM 1800 1805-1880 MHz The distance to be jammed (D) This parameter is very important in our design, since the amount of the output power of the jammer depends on the area that we need to jam. Later on we will see the relationship between the output power and the distance D. Our design is established upon D=10 meters for GSM 1800 band and D=20 meters for GSM 900 band. 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.Jamming–to-signal ratio {J/S} Jamming is successful when the jamming signal denies the usability of the communication transmission. In digital communications, the usability is denied when the error rate of the transmission can not be compensated by error correction. Usually, a successful jamming attack requires that the jammer power is roughly equal to signal power at the receiver (mobile device). The general equation of the jamming-to-signal ratio is given as follows: Jamming–to-signal ratio {J/S} = PjGjrGrj R2trLr Br / PtGtrGrt R2jrLjBj where: Pj=jammer power, Gjr= antenna gain from jammer to receiver, Grj=antenna gain from receiver to jammer, Rtr=range between communication transmitter and receiver, Br=communication receiver bandwidth, Lr =communication signal loss, Pt=transmitter power, Gtr= antenna gain from transmitter to receiver, Grt=antenna gain from receiver to transmitter, Rjr=range between jammer and communication receiver, Bj=jammer bandwidth, and Lj=jamming signal loss.For GSM, the specified system SNRmin(Minimum detectable signal (MDS) by a device) is 9 dB which will be used as the worst case scenario for the jammer.
The Power supply This is used to supply the other sections with the needed voltages. Any power supply consists of the following main parts: Transformer: - is used to transform the 220VAC to other levels of voltages. Rectification: - this part is to convert the AC voltage to a DC one. We have two methods for rectification: A] Half wave-rectification: the output voltage appears only during positive cycles of the input signal. B] Full wave –rectification: a rectified output voltage occurs during both the positive and negative cycles of the input signal. The Filter: used to eliminate the fluctuations in the output of the full wave rectifier “eliminate the noise” so that a constant DC voltage is produced. This filter is just a large capacitor used to minimize the ripple in the output. Regulator: this is used to provide a desired DC-voltage. IF-SectionThe function of the IF-section of the mobile jammer is to generate the tuning signal for the VCO in the RF-Section, which will sweep the VCO through the desired range of frequencies. This tuning signal is generated by a triangular wave generator((To tune the VCO in the RF section) along with noise generator(provides the output noise), and Mixer summer((to mix the triangle and the noise waves). RF Section The RF-section is the most important part of the mobile jammer , it consists of the VCO,RF Power Amplifier, and the antenna.VCO: The VCO is responsible for generating the RF signal which will over power the mobile downlink signal. It should match the frequency of the GSM system.Power Amplifier: It is needed to amplify the to increase the VCO output to a desired range.Antenna: A proper antenna is necessary to transmit the jamming signal. In order to have optimal power transfer, the antenna system must be matched to the transmission system.