Delay Adaptive Differential Pulse Code Modulation System,
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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 25, 1971
- Accession Number
- AD0726668
Entities
People
- Ying Hui Shih
Organizations
- North Carolina State University