A robust, low complexity 5.0 kbps stochastic coder for a noisy satellite channel

Abstract

A code excited linear predictive coding (CELP) based coder operating at 5065 bps is presented. The coder uses a self-excitation sequence for long-term prediction in addition to a fixed codebook populated with stochastic multipulse vectors as the excitation signal. The authors describe how the complexity of the coder is reduced, and present methods of increasing its spectral robustness, thus making it a suitable candidate for mobile satellite communication. The complexity is greatly reduced by using overlapping codevectors in both the adaptive and multipulse codebook. For robustness a filter correction scheme is derived, which, together with frame repetition techniques, will let the coder operate with little perceivable degradation in burst durations up to 40 ms.