Rate-distortion performance in coding bandlimited sources bysampling and dithered quantization

摘要

The rate-distortion characteristics of a scheme for encodingcontinuous-time band limited stationary sources, with a prescribed band,is considered. In this coding procedure the input is sampled atNyquist''s rate or faster, the samples undergo dithered uniform orlattice quantization, using subtractive dither, and the quantizer outputis entropy-coded, The rate-distortion performance, and the tradeoffbetween the sampling rate and the quantization accuracy is investigated,utilizing the observation that the coding scheme is equivalent to anadditive noise channel. It is shown that the mean-square error of thescheme is fixed as long as the product of the sampling period and thequantizer second moment is kept constant, while for a fixed distortionthe coding rate generally increases when the sampling rate exceeds theNyquist rate. Finally, as the lattice quantizer dimension becomes large,the equivalent additive noise channel of the scheme tends to be whiteGaussian, and both the rate and the distortion performance becomeinvariant to the sampling rate