Transmission power of gsm interceptor

Perfectjammer 2022/11/01

　　A gsm jammer is an electronic device that blocks signals from mobile phones.In the actual communication process, at a certain time and place, the actual transmit power of the mobile phone depends on the environment, the system's requirements for communication quality, voice activation and many other factors, which actually depend on the link budget of the system.

　　The device transmits at a lower power level than other mobile devices to protect the human body and reduce interference.The frequency of adjustment is once every 60ms.Currently, the network actually allows a maximum transmit power of 23dBm (0.2W).The specification does not require the minimum transmit power of CDMA mobile phones.At present, the commonly used GSM mobile phone has a maximum transmit power of 2W (33dBm) in the 900MHz frequency band, and a maximum transmit power of 1W (30dBm) in the 1800MHz frequency band.Let's compare the initial value of GSM and CDMA mobile phone transmit power and the power control mechanism.

　　Depending on the type of equipment used, power levels can range from zero to a few decibels or more.To ensure successful access, the mobile phone transmits at the maximum power allowed by the system (usually the maximum transmit power of the mobile phone).Our 2G includes both GSM and CDMA technologies.The communication between the mobile phone and the system can be divided into two stages, one is the access stage, and the other is the traffic communication stage.

　　However, these factors can only be used to determine the effectiveness of the device.For the GSM system, the mobile phone has no power control until it enters the dedicated mode in the random access phase.This power level is regulated by local regulators.After the dedicated channel (SDCCH or TCH) is allocated, the mobile phone will adjust the transmit power of the mobile phone according to the instructions of the base station, and the adjustment step is usually 2dB.

　　At the same time, the specification requires that for the GSM900 and 1800 frequency bands, the minimum transmit power of the mobile phone during the communication process should not be lower than 5dBm.and 0dBm.The gain is 21dB, (the gain for other low-rate codes is greater), so the requirement for the equivalent carrier-to-interference ratio of the signal before despreading is less than -14dB! (The CDMA system usually needs about 7dB after despreading) .

　　The CDMA IS-95A specification requires a maximum transmit power of 0.2W to 1W (23dBm to 30dBm) for mobile phones.In the usual network design and planning, for basically the same frame error rate requirements, the GSM system requires that the carrier-to-interference ratio of the mobile phone signal reaching the base station is usually about 9dB.

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