Blue listener software APP official website template

The principle of GSM is to encode, encrypt, and interleave the voice signal channel on the system channel to form a burst pulse train that is modulated and then transmitted. At the mobile phone receiving end, the signal is demodulated, deinterleaved, channel decoded, and voice decoded, and then restored to a voice signal in the user's mobile phone. The GSM system uses narrowband time division multiple access (TDMA) technology during the transmission process. The bandwidth of each carrier channel is 200KHz, and each frame has 8 time slots. In theory, one radio frequency can conduct 8 groups of calls at the same time, and each time slot The length is 0.577ms, and the frame duration is 4.615ms. It divides time into periodic frames, and each frame is divided into many time slots. Then, according to the specific time slot allocation principle, mobile phone users can specify in each frame In the time slot, signals are sent to the base stations, and the base stations are in their respective designated time slots. After receiving signals from different mobile phone users, the base station also transmits signals to different mobile phone users according to the specified time slot. Each mobile user receives the signal in the specified time slot. This does not guarantee that the signals are on the same channel. Users can not interfere with each other. This is why individual mobile users occasionally hear other people's conversations from the microphone when using mobile phones. When consulting the operator on this issue. They won't say, and of course, they won't say at what point the cell phone monitors are monitored.