Quantizing schemes for the discrete Fourier transform of a random time-series

Abstract

The problem of quantizing a large-dynamic-range, possibly nonstationary signal after it has been transformed via the discrete Fourier transform (DFT) is investigated. It is demonstrated that, for purposes of d, the polar-form representation for these DFT coefficients is preferable to the Cartesian-form when fixed-information-rate quantization schemes are considered. A technique called spectral phase coding (SPC) is described for transforming the DFT coefficients into a bounded sequence\{\psi_{p}\}, where- \pi < \psi_{p} \leq \pi. In most cases, the terms\psi_{p}are uniformly distributed over this range. The results indicate that SPC is a robust suboptimum procedure for coding nonstationary or large-dynamic-range signals into digital form.