Adaptive high speed data modems

Abstract

This paper summarizes two high-speed, adaptive modems for voice-band channels. The first is a 4800 bps, MOS/LSI modem which is almost entirely contained on 5 to 8 MOS/LSI chips, depending upon the version. The second modem is experimental and employs advanced, novel techniques for automatic equalization, carrier recovery, timing recovery, and jitter correction. Partial response, SSB signaling provides both high bandwidth efficiency and error correction without digit redundancy. Measured performance curves, including bit error rates, show that, under various transmission conditions, this modem provides outstanding performance. Implementation on a few MOS/ LSI chips or in an inexpensive signal processor is feasible.