A comparative study of DPCM-AQF speech coders for bit rates of 16-32 kb/s

A comparative study of DPCM-AQF speech digitizers employing various second order prediction algorithms is presented. A new prediction scheme called Correlation Switched Prediction is also discussed. Computer simulation results for the range of 16 to 32 kbits/sec, indicate an improved segmented signal-to-noise ratio (SNRSEG) performance when using Forward Block Adaptive (FBA) instead of Backward Sequentially Adaptive Prediction. The introduction, in DPCM-AQF, of the relatively simple Correlation Switched Predictor produces SNRSEG values comparable to those obtained from DPCM-AQF-FBA. A more complex prediction scheme which combines Correlation Switched and Backward Sequential Adaptive Prediction (CSP-SGEP) is also considered. DPCM-AQF using the latter prediction is shown to provide the best overall SNRSEG performance.