GB1388397A - Digital signal transmission systems - Google Patents

Abstract

1388397 Digital transmission; duplex signalling K W CATTERMOLE and G B B CHAPLIN 27 Sept 1972 [27 Sept 1971] 44940/71 Heading H4P In a system for simultaneous transfer of digital signals in opposite directions along a channel between stations each having a transmitter and receiver, and in which the duration of received pulses are longer due to channel dispension than transmit pulses, the receiver includes means for inhibiting detection for the duration of each transmit pulse, the detector being responsive to mutiliated pulses resulting from suppression of a part. The detector may include means for performing a weighted integration of multilated pulses and testing the value at determined instants. A repeater incorporating such features may be connected into channel 3, 4 via half equalizers 9, 10 and optional hybrid transformers 5, 6. Incoming signals on line 3 are directed to the input of preamplifier 11A and passed to a sample and hold circuit 12A where influence of outgoing signals on line 3 is removed. Output signals are generated and applied to detector 13A producing two outputs, one to rectifer 15A from which is derived a series of short pulses driving resonator 16A generating sinusoidal oscillations of pulse repetition frequency which are applied to generator 17A and back to 13A to mark digit times and enable detector 13A to produce its second output as a ternary code to regenerator 18B, also controlled by 17A, thus producing a signal for transmission by hybrid transformer 6 and half equalizer 10. Incoming signals on line 4 are similarly passed to line 3 via components bearing suffix B and a timing distributor 14A acts on 12A to act on line 4 signals. A terminal station would comprise only half the components described; a part of 17A would not be required, a source of pulses being necessary. A form of sample and hold circuit is described in connection with Fig. 10 (not shown).