Abstract

1. In a communication system, a first delay line having multiple spaced taps, means for supplying successive input pulses to said delay line, whereby in response to each input pulse variously delayed pulses appear at the taps of said delay line, means for deriving from said taps pulses representative of a MARK, means for also deriving from said taps pulses representative of a SPACE, means for selecting the MARK and SPACE representative pulses according to sigal intelligence representable by MARKS and SPACES, means for effecting carrier transmission of the selected pulses, means for receiving the carrier-transmitted pulses, a pair of synchronous detectors, means for supplying the carrier-transmitted pulses to said detectors, means for supplying phase quadrature related local oscillations respectively to said detectors, a second multi-tap delay line which is the conjugate of said first delay line, means for driving said second delay line from said detectors, and means for deriving the transmitted MARK-representative and SPACE-representative pulses from said second delay line.