QCELP Vocoders Design in CDMA System
Qi Yong · Journal of Information Engineering University · 2002
In wideband spread spectrum systems, QCELP 8 kbps and 13 kbps voice coders (vocoders) are speech coding standards. Dynamically adjusting the coding data rate makes the QCELP algorithm different from the traditional CELP algorithm. It significantly reduces the average encoded data rate without sacrificing the voice quality. This paper describes the basic principles and key features of QCELP vocoders, including functional structures and signal processing flow in each major module. Finally,the difference of performance between QCELP and traditional CELP is presented. And the performance of QCELP when implemented in DSP is discussed.