| 摘要 |
<p>PHF 78/570 This system comprises an encoder in which the differential PCM signal to be transmitted is formed as the difference between the incoming linear PCM signal and a prediction signal produced by a prediction filter comprising a local decoder receiving the said differential PCM signal. According to the invention the local decoder and the remote decoder are constructed in an identical manner by means of one or several filtering sections arranged in cascade, each filtering section being of the purely recursive or non-recursive type with one sole coefficient differing from zero and having been provided with its own roundoff (or truncation) device having a step size equal to the quantizing step of the differential PCM signal, the incoming linear PCM signal being rounded (or truncated) in the same manner, This construction enables the cascade arrangement of encoders and decoders without any further degradation of the signal then the degradation produced by the first coding. Used in signal transmission in telephone networks.</p> |
