Modem designs, and systems using the modem designs for communicating information between a number of remote locations and one or more central locations

摘要

Various modem designs are described, along with systems that use the modem designs for communicating data between a large number of remote locations and one or more central locations preferably over CATV. One aspect features a modem having a transmitter which uses a state machine and digital waveform signals stored in a memory to create a modulated signal. Another aspect features a modem having a receiver which uses a digital correlator including an SRAM for detecting a bipolar phase shift keyed signal. Still another aspect features a modem comprising an oscillator circuit having a feedback loop, wherein the feedback loop utilizes a downlink signal, and a protection circuit which prevents a malfunction in the modem from causing system-wide shutdown.