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Convention Paper

Companded Predictive Delta Modulation: A Low-Cost Conversion Technique for Digital Recording

Authors: Adams, Robert W.

AES Convention 73 · Paper 1978 · March 1983

Abstract

A digital recording system has been designed which employs a new type of A/D converter in place of the 16-bit linear PCM converters currently in use. The conversion process described in this paper is called Companded Predictive Delta Modulation, and differs from adaptive delta modulation in that the input signal is dynamically adjusted by a voltage-controlled amplifier and then passed through a fixed (nonadaptive) delta modulator. Dither is added to provide a white noise floor and minimize low-level distortion. Instead of a simple integrator, the delta modulator uses a second-order feedback filter, which substantially increases its dynamic range. (If nonlinear stabilization techniques are employed, high-order filters may be used.) Since delta modulators have low sensitivity to bit errors, the error-correction circuitry can be simplified. A convolutional error-correction code was chosen for this application.

Details

Published in
AES Convention 73
AES Convention
73
Paper number
1978
Publication date
March 6, 1983
Session subject
Applications in Digital Audio
Affiliation
DBX Inc., MA (See document for exact affiliation information.)
Type
Convention Paper