Apparatus and method for ordering independent signals

摘要

A method of and apparatus for modulating, demodulating, and ordering independent signals transmitted over a single link provides mux-demux capability by asymmetric average interpulse spacing so that the information will be received only by the proper listening station despite interruptions or errors in transmission. In the two signal embodiment, a master oscillator provides an asymmetric carrier pulse train to a pair of ramp generators, one leading pulse edge triggered and the other trailing edge triggered. The ramps pulse position modulate the signals by means of a pair of comparators. The modulated outputs of the comparators are applied to an OR gate which combines the pulses to provide a time division multiplexed stream of modulated data having an asymmetric average interpulse spacing. The data stream is transmitted over a pulsed data link to a pair of synchronizers, each of which contains a phase-locked loop having a voltage controlled oscillator whose free running pulse repetition frequency is one-half that of the multiplexed stream and whose loop filter high frequency cutoff is considerably below the lowest modulation frequency. A flip-flop correlator compares the average start times of the voltage controlled oscillators of the two phase-locked loops to provide the control signals for a steering network which directs each of the signals to the proper listening station, assuring the independence of the transmissions.