18-02-2011, 04:37 PM
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GSM-900 Mobile JAMMER
INTRODUCTION
A GSM Jammer is a device that transmit signal on the same frequency at witch theGSM system operates, the jamming success when the mobile phones in the area wherethe jammer is located are disabled.
Communication jamming devices were first developed and used by military. Wheretactical commanders use RF communications to exercise control of their forces, an enemyhas interest in those communications. This interest comes from the fundamental area ofdenying the successful transport of the information from the sender to the receiver.
owadays the mobile jammer devices are becoming civilian products rather thanelectronic warfare devices, since with the increasing number of the mobile phone usersthe need to disable mobile phones in specific places where the ringing of cell phonewould be disruptive has increased. These places include worship places, university lecture rooms, libraries, concert halls, meeting rooms, and other places where silence is appreciated.Mosques are example for the places were mobile jammer would be a great solution, although mosques asks politely from prayers to disable their mobile phone during the prayer ,see figure (1), some people forget and the ringing phone of their mobile phone become very annoying specially during the praying time.
Mobile Jamming and Disablers Techniques
There are different approaches to prevent mobile phones from ringing in specific area, the main five approaches used or being developed are described in RABC Mobile & Personal Communications Committee’s (M&PCC) meeting of June 22, 1999 [1], these techniques are summarized in this section :
1- Type "A" Device
In this device we overpower cell phone's signal with a stronger signal, This type of device 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.”
2- Type "B" Device
This device also called "Intelligent Cellular Disablers devices", and it does not transmit an interfering signal on the control channels. The device basically works as a detector, and it capable to communicate with the cellular base station. 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. The
device 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.
This intelligent device as it’s name imply can recognize emergency calls and also can allow specific pre-registered users to use their mobile phones for a specified duration. Although this device sounds the best solution for disabling mobile phone, a provision is needed by the cellular/PCS service providers or provision by a third- party working cooperatively with full support of the cellular/PCS service providers, allowing the detector device to be integral part of the cellular/PCS systems.
3- Type "C" Device
This device also called "Intelligent Beacon Disablers ", as in the type "B" device it does not transmit an interfering signal on the control channels.
The device, when located in a specific "silent" room, functions as a ‘beacon’ and any compatible terminal is ordered to disable its ringer or disable its operation. Inthe coverage area of the beacon only terminals which have a compatible receiverwould respond and this should be built on a separate technology from cellular/PCS,or example Bluetooth technolo. Also the handset must re-enable its normalfunction as it leaves the coverage area of the beacon.The need for intelligent handsets with a separate receiver for the beacon receiverfrom the cellular/PCS receiver, make effective deployment for the type "C" devicewill be problematic for many years.
GSM-900 Mobile JAMMER
INTRODUCTION
A GSM Jammer is a device that transmit signal on the same frequency at witch theGSM system operates, the jamming success when the mobile phones in the area wherethe jammer is located are disabled.
Communication jamming devices were first developed and used by military. Wheretactical commanders use RF communications to exercise control of their forces, an enemyhas interest in those communications. This interest comes from the fundamental area ofdenying the successful transport of the information from the sender to the receiver.
owadays the mobile jammer devices are becoming civilian products rather thanelectronic warfare devices, since with the increasing number of the mobile phone usersthe need to disable mobile phones in specific places where the ringing of cell phonewould be disruptive has increased. These places include worship places, university lecture rooms, libraries, concert halls, meeting rooms, and other places where silence is appreciated.Mosques are example for the places were mobile jammer would be a great solution, although mosques asks politely from prayers to disable their mobile phone during the prayer ,see figure (1), some people forget and the ringing phone of their mobile phone become very annoying specially during the praying time.
Mobile Jamming and Disablers Techniques
There are different approaches to prevent mobile phones from ringing in specific area, the main five approaches used or being developed are described in RABC Mobile & Personal Communications Committee’s (M&PCC) meeting of June 22, 1999 [1], these techniques are summarized in this section :
1- Type "A" Device
In this device we overpower cell phone's signal with a stronger signal, This type of device 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.”
2- Type "B" Device
This device also called "Intelligent Cellular Disablers devices", and it does not transmit an interfering signal on the control channels. The device basically works as a detector, and it capable to communicate with the cellular base station. 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. The
device 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.
This intelligent device as it’s name imply can recognize emergency calls and also can allow specific pre-registered users to use their mobile phones for a specified duration. Although this device sounds the best solution for disabling mobile phone, a provision is needed by the cellular/PCS service providers or provision by a third- party working cooperatively with full support of the cellular/PCS service providers, allowing the detector device to be integral part of the cellular/PCS systems.
3- Type "C" Device
This device also called "Intelligent Beacon Disablers ", as in the type "B" device it does not transmit an interfering signal on the control channels.
The device, when located in a specific "silent" room, functions as a ‘beacon’ and any compatible terminal is ordered to disable its ringer or disable its operation. Inthe coverage area of the beacon only terminals which have a compatible receiverwould respond and this should be built on a separate technology from cellular/PCS,or example Bluetooth technolo. Also the handset must re-enable its normalfunction as it leaves the coverage area of the beacon.The need for intelligent handsets with a separate receiver for the beacon receiverfrom the cellular/PCS receiver, make effective deployment for the type "C" devicewill be problematic for many years.
