The Research Of Speech Processing Used In Digital Interphone Based On DSP

In the system of trunk communication, the quality of speech should be clear and robust enough in the noisy environment, the complexity of speech algorithm should be appropriate, the equipments of signal processing in handsets should be cost-effective and low power.Continuously Variable Slope Delta Modulation (CVSD) is a speech algorithm that widely applied in the field of wireless communication, such as satellite communication system, mobile communication system, military special communication net, and so on. ITU released the standards of 16kbps & 32kbps CVSD.The thesis is based on the interphone handset. First, it researches on the speech algorithm CVSD that used in the special speech processing chipset, then it proved that CVSD can maintain the quality of speech by emulating in matlab, and ameliorated the quality of speech by using suitable filter.At the same time, considering of the limits of special speech processing chipset, such as high price, difficulty in changing algorithm, carrying out CVSD algorithm on DSP instead of the special speech processing chipset is a better way. The experiment confirms that the quality of human speech can be maintained after encoding and decoding by CVSD algorithm based on DSP So it gives another method to deal with the speech processing base on interphone handset. Finally, the thesis discusses a new structure of the interphone handset and communication protocol based on CVSD and DSP.