A Simple PCM Coder with Improved Quantizing Noise
Joydeep Das, Prayosi Chatterjee · IETE Journal of Research · 1966
Tapped LC-delay lines have been used as coding networks to construct simple PCM coders, whose performances are similar to those of conventional systems. The binary coding technique has been extended to generate ternary-PCM codes. The approximated signal is available at the transmitter readily and the continuous comparison between the reconstructed and original signals through a secondary feedback loop has been used to reduce the quantizing noise. Considerable improvement in SNR has been obtained with this analogue feedback method, but the improvement is limited by the loop delay of the system and the saturation limit of the coder. The overall characteristics of the feedback-PCM systems are found to be better than those of the conventional PCM using six or less digits in the coder.