Abstract: To enhance the detection of a desired signal in the presence of interference, the degree of modulation of a received input signal is amplified. In the preferred embodiments, this is accomplished by amplifying the degree of amplitude modulation. This works especially well in situations where constant or substantially constant envelope jamming is employed. However, the arrangement is also effective in some cases where the jamming signal has a rapidly fluctuating envelope. The success of the technique in cases of rapidly fluctuating envelopes depends upon the probability distribution of the envelope.

Abstract: An automatic alignment system for use in a digital modem, having a performance indicator circuit associated therewith, adjusts the control voltages applied to selected alignment points therein in order to minimize the error indication output of the performance indicator circuit. The alignment system interfaces with a microprocessor and provides the necessary timing mechanism to generate write pulses which control the operation of respective processing circuits associated with the various alignment points in the modem analog unit. Each of the processing circuits in the modem analog unit includes a digital-to-analog converter, a data latch, and an amplifier which processes the output of the microprocessor interface to generate an analog control voltage.