International Telephone and Telegraph Corporation

Itt Defense Communications, a Division of Itt Corporation

Philip Duncan Carmichael

James Grant Dunn

Thomas E Finley

A digital divider with both integral and fractional division capabilities is provided by utilization of a counter and one decoder to trigger phase reversal and a second decoder to trigger short-cycling of the counter. The first decoder provides phase reversal to cause extra half pulses during the period established by the second decoder to thus create the fractional count needed for fractional division. A control input is included to select either whole number division or fractional division.

Digital divider with integer and fractional division capability

In the transmitter portion a multiplexer multiplexes first digital data and first teletype signals to provide first digital data signals. The first digital data signals are converted into second digital data signals having a different form than the first digital data signals by a Viterbi coder. A PSK modulator responsive to the second digital data signals provides a first PSK signal for transmission. In the receiver portion a PSK demodulator receives a second PSK signal containing third digital data signals having multiplexed second digital data and second teletype signals with the third digital data signals being extracted from the second PSK signal. A Viterbi decoder converts the third digital data signals into fourth digital data signlas having a different digital form than the third digital data signals. A PSK demultiplexer is responsive to the fourth digital data signals to separate the second digital data and the second teletype signals for utilization. The arrangement to extract the third digital data signals from the second PSK signals includes the PSK demodulator and a Costas' type phase locked loop including a number controlled oscillator, a digital phase shifter, an accumulator arrangement including three accumulators accumulating different data and errors, a clock recovery circuit and a loop filter controlling the number controlled oscillator.

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Closter, NJ, United States of America

Philip Duncan Carmichael