| The main task of this thesis is to design a voice compression/decompression communication system based on the AMBE-2000TM vocoder chip. A special voice compression/decompression chip, based on the standard-setting advanced AMBE voice compression software algorithm, is used in this system. It can achieve high compression rate at 2.4kbps and reduce the space of saving data and efficiently save band-width.In this paper, we have presented in detail the configuration of the voice communication system and the controlling of timing sequence. The system is full-duplex. At the sending end, the input analog speech signal is sent into A/D coder to perform the A/D conversion. The PCM signal, get from the conversion, is then sent into the compression/decompression chip to be encoded. By sending the coding data packages to the controlling chip (FPGA), the process of extracting voice data, relaxative saving in FIFO and simultaneously adding synchronous header to be sent out at low data rate for the coding data packages is accomplished. In addition, at the receiving end, by receiving low bit rate data, reformation of the frame in FPGA is achieved. The PCM signal, get from the process of decompressing in the compression/decompression chip, is sent to D/A coder to perform D/A switching. The signal is then amplified in the power amplifier to renew the original sound and finally... |
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