Accession Number:

AD0726668

Title:

Delay Adaptive Differential Pulse Code Modulation System,

Descriptive Note:

Corporate Author:

NORTH CAROLINA STATE UNIV RALEIGH DEPT OF ELECTRICAL ENGINEERING

Personal Author(s):

Report Date:

1971-04-25

Pagination or Media Count:

230.0

Abstract:

A delay adaptive differential pulse code modulation system, consisting of a delay adaptive predictor and a delay adaptive quantizer, is investigated. These components are first analyzed separately, and then in combination, using a stationary Gaussian Markov signal. They employ a buffer to store a segment of the signal at a time. Parameters are computed from each segment, and then used to encode this segment. It is shown that the delay adaptive can achieve a significantly lower mean square prediction error than the analogous nonadaptive predictor. A technique of delay adaptive quantization, in which the levels of a core quantizer are scaled in proportion to the local r.m.s. value of the signal, is described and analyzed. The signal-to-quantizing noise ratio of the delay adaptive differential pulse code modulation system is obtained. For small learning periods, this SNR is very close to a general upper bound for digital encoding systems. Finally, the transmission of the adaptive parameters to the receiver is considered. The parameters must be quantized uniform quantizers are employed. The SNR is obtained as a function of total channel bit rate and compared to a bound for nonadaptive DPCM. The system performs quite well for learning periods larger than about fourteen samples. Author

Subject Categories:

  • Cybernetics
  • Voice Communications

Distribution Statement:

APPROVED FOR PUBLIC RELEASE