A robust, adaptive transform coder for 9.6 kb/s speech transmission

This paper will describe the design of a robust 9.6 kb/s speech transmission system which degrades slowly under high error rate conditions. The system is based upon a combination of adaptive transform coding (ATC) principles and a vocoder-driven strategy (VDS) proposed by previous authors and operates in real-time on a commercially available array processor (1), (3). The channel error protection process utilizes a fixed block length BCH code on a rank ordered message list composed of discrete cosine transform (DCT) coefficients and side band information. The resultant system exhibits little degradation at 1 percent channel error rates and is not degraded perceptually by inaccurate pitch estimation.