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Power spectra of ADPCM

1977; Institute of Electrical and Electronics Engineers; Volume: 25; Issue: 1 Linguagem: Inglês

10.1109/tassp.1977.1162902

0096-3518

Bede Liu, L. H. Goldstein,

Advanced Adaptive Filtering Techniques

We consider the power spectra of signals modulated by adaptive differential pulse-code modulators (ADPCM) and adaptive delta modulators (ADM). A technique for computing these spectra without the significant use of hardware multipliers is presented. A fast Fourier transform (FFT) implementation is then described that uses an ADPCM signal as input and accomplishes the necessary code conversion and computation with a saving in hardware over conventional designs. Finally, simulations of RC-filtered Gaussian signals modulated by ADM and ADPCM systems are used to provide some insight into the problem of how well the spectra of signals modulated in this manner approximate the original input signal spectra.