.21 V.21 PREAMBLE TONE DETECTING METHOD OF BASE STATION CONTROLLER IN THE WLL SYSTEM

摘要

The present invention relates to a V.21 preamble tone detection method for a WLL system in the control station to the V.21 preamble incoming tone via the in-band when the data service to the control station vocoder detected by software, QCELP encoding unit and decoding unit and the QCELP V.21 preamble tone detector configuration step of configuring and operating a separate V.21 preamble tone detector for detecting a V.21 preamble tone in the vocoder, the V.21 preamble tone and a signal detecting step of storing the signal in the energy level has a value larger than a certain degree is detected that has a value above a certain level for a V.21 preamble tone detector configured in configuration phase detection signal to the incoming vocoder buffer, and the FFT conversion step of converting the signal detected by the signal detecting step FFT, frequency-band through the FFT transform in the FFT conversion step Or if the signal from a vocoder to measure the audio signal and the energy V.21 preamble tone is determined whether the energy level comparing step of, in said energy level comparison stage determination result, V.21 preamble tone vocoder is selected when it is determined that perform a service option change request to the processor to switch to data service mode and, if the predetermined time is elapsed after V.21 preamble tone is detected comprising the further pre do not execute the data service preamble tone detection operation mode switching step and that is characterized.