Signal multiplexer and demultiplexer

Claim 1

Improved apparatus for supplying at a remote site the information content of at least three pulse trains, the first and second of the trains comprising respectively, periodic timing pulses of relatively low and high frequencies and whose pulses on occasion coincide, and the third pulse train comprising aperiodic data pulses of varying duration occurring between the timing pulses, wherein the improvement comprises: a. means receiving the pulse trains for providing a composite signal following the instantaneous sum of voltages of said pulse trains; and b. separating means for receiving the composite signal and reproducing from the composite signal a plurality of signals, each comprising pulses corresponding to the pulses in one original pulse train, comprising i. level sensing means for producing a data signal pulse whenever composite signal voltage reaches a predetermined value; ii. frequency-tuned means for producing timing pulses corresponding to those of the first timing pulse train; and iii. means reproducing the second timing pulse train for attenuating all composite signal frequency components outside a predetermined bandwidth surrounding the frequency of the second pulse train, and producing a pulse of the second train each time signal voltage falls within a predetermined range.