Abstract: 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.

Abstract: A multi-channel adaptive threshold circuit usable to extract affirmative detection impulses from a plurality of detection circuits each having a different background noise level. The circuit comprises a plurality of analogous detection circuits whose outputs are coupled in parallel between a threshold circuit and threshold activation device such as a switch which grounds all outputs when in the ON position. The input to each detection circuit, which is a composite of sporadic affirmative return pulses and continuous background noise, is passed through a unidirectional conducting device, such as a base-to-emitter junction of a transistor, to charge a capacitor to a value which is a function of the continuous background noise. When the threshold activation device is turned off, the output plate of the capacitor of each detection circuit is applied to a fixed threshold circuit.