Envelope Dynamic Ratio Quantizer
Costas S. Xydeas, M. Faruqui, Robert JC Steele · IRE Transactions on Communications Systems · 1980
The envelope dynamic ratio quantizer (envelope DRQ) is an adaptive quantizer for speech signals. By utilizing the envelope of the speech, nonlinear elements, a fixed quantizer and a simple predictor, a closed-loop adaptive quantizer emerges having a high constant SNR over a wide dynamic range. The theory of the quantizer is presented, together with computer simulation results which show an improvement.compared to the one word memory APCM system. Finally, the simplicity of implementing the envelope DRQ is described.