Patent ID: 6922402

Claim:
A full duplex communications link comprising: first receiver means for receiving a first signal at a first predetermined frequency, the receiver means having a signal input, data output, and an offset signal output representing the frequency difference between the first predetermined frequency and the frequency of the first signal, first transmitter means for transmitting a second signal at a second predetermined frequency, the transmitter means having a data input, frequency tuning input, and a signal output, first control means taking the offset signal from the first receiver and producing the frequency tuning input for the first transmitter, signaling the offset in the first signal to the second receiver, second receiver means for receiving the second signal at the second predetermined frequency, the receiver means having a signal input, data output, and an offset signal output representing the frequency difference between the first predetermined frequency and the frequency of the second signal, second transmitter means for transmitting the first signal at the first predetermined frequency, the transmitter means having a data input, frequency tuning input, and a signal output, and second control means for taking the offset signal from the second receiver and producing the frequency tuning input for the second transmitter, thereby responding to the offset sensed by the first receiver, and correcting the frequency of the second transmitter accordingly.