Realization of an adaptive delta modulation codec robust to channel errors

An adaptive delta modulation codec with companding logic incorporating an algorithm which automatically corrects mistracking between the coder and decoder logic circuits is described in this paper. The performance of this codec is evaluated using both computer simulation and hardware realization. The results show that at 64-kHz sampling rate using seven different quantizing steps, 30-40-dB S/ can be obtained for 900-Hz sinusoidal input over the input range of 50 dB. The mistracking correction time is calculated to be 0.5-2.5 ms for single channel error case and 1-7 ms for a larger mistracking case like at the moments of power application. The entire codec was realized on a 12 by 5- printed circuit board using a custom designed LSI for the companding logic part.