Racal Data Communications Inc.

Racal-milgo Limited

Yoon B Park

Ran F Chiu

Charles R Baugh

William A Dambrackas

David E Nizel

Edwin J Hilpert

George R Kushin

In a data communication system involving modems transmitting over a link including terrestrial and one or more satellite links, a nontransmitting modem sends a secondary channel tone during the absence of data transmission. The cessation of said tone is detected by the other modem and used to de-squelch the remote modem receiver. In this manner, the receiver is protected from echoes impinging upon it during long transmission delay times. This method optimizes data throughput by adapting to the transmission delay of the circuit.

Method and apparatus for maximizing efficiency in satellite

An automatically adjusted equalizer circuit includes an operational amplifier having a parallel resonant circuit, a voltage controlled resistor, and an amplifier output signal monitoring circuit in a feedback path for the adjustable equalizer. The presence of the parallel resonant circuit in the feedback path causes the amplifier gain to vary with frequency. An input signal to the operational amplifier will be distorted depending upon the particular loss characteristic of a telephone wire to which the input is connected. Automatic adjustment of the voltage controlled resistor, and the presence of the resonant circuit, causes the slope of the gain of the amplifier to inversely compensate for the loss characteristic of the particular line in question. Within the variety of lines, each line will have different loss characteristics as a function of length and gauge of the different telephone lines. This equalizer automatically provides a compensated output signal which is equalized for the particular loss characteristic of the line selected from such a variety of lines.

Adaptive equalizer for short distance metallic circuits

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Miami, FL, United States of America

Yoon B Park