Abstract: A communication signalling system containing a control unit receiving input data from one source and a reference signal from another source, a modulator receiving an input from the control unit, and a plurality of tones from a separate source, the phase of each of the tones received by the modulator being modulated in response to the input received from the control unit, an adder which receives the modulated signals from the modulator and converts the signals into a composite signal which is then sent to a latch unit which also receives a signal from a symbol interval clock, the latch unit sending a composite signal to a transmitter for transmission during a given symbol interval, an antenna and receiver detector unit for receiving the signal being transmitted, the signal being forwarded to a filter and correspondence circuit which breaks out the individual modulated signals comprising the original frequency, the modulating phase, and a random unknown interference, the individual signals being applied to and

Abstract: A multitone DPSK modulator produces a composite analog signal in which the phases of the tones included within the composite analog signal represent data. The modulator uses digital circuitry to synthesize a plurality of analog tones simultaneously. On a periodic basis, input digital data controls the amount by which the phase of each of the component tones is shifted. Synthesis is accomplished by periodically retrieving signals from a sine table and applying the retrieved signals to a D/A converter. A composite analog signal is sythesized by summing a retrieved signal from the sine table for each of the component tones during each sampling period. The number of tones included within the composite analog signal and the frequency, amplitude and starting phases of each of the component tones may be programmed and thus readily changed.