HIGH SPEED HALF DUPLEX MODEM WITH FAST TURNAROUND PROTOCOL

摘要

A modem with improved signal processing and handshaking capabilities as described. Two digital signal processors are used to perform indpendent, concurrent operations so that a faster execution rate is obtained and more precise calculations are made possible. The modem also uses an improved handshaking technique which allows the modem to maintain compatibility with existing 1200 and 2400 bps modems while allowing for negotiation for 4800 and 9600 bps communications. The modem also incorporates an improved baud clock recovery circuit which dynamically adjusts the actual sampling point in a manner dependent upon the difference between the actual sampling point and the optimal sampling point. This allows the actual sampling point to converge upon the desired sampling point at a high rate while minimizing jitter around the optimal sampling point.