GB1442444A - Signal decoder - Google Patents

Abstract

1442444 Signal decoding INTERNATIONAL BUSINESS MACHINES CORP 30 Aug 1973 [7 Sept 1972] 40776/73 Heading G4C A signal decoder for decoding binary information, e.g. from a magnetic record, carried by a train of regular clock pulses or transitions, binary digits of one value being represented by the presence and those of the other value by the absence of a pulse or transition in the interval between the clock pulses or transitions, comprises circuitry for producing an interval signal representative of the time interval between each pulse or transition and the preceding clock pulse or transition, for storing an associated reference signal related to the interval between the preceding pair of clock pulses or transitions, and for comparing each interval signal and its associated reference signal to decode the pulse train by identifying each pulse or transition as a clock pulse or transition or as representing a binary digit of the one valve. Several circuit embodiments are described, it being stated that a programmed computer could be used. In a first embodiment Fig. 2 the pulse train is applied at input 200, each clock pulse switching flip-flop 212 to actuate ramp generators 214, 216 alternatively, the signal levels of the ramps being compared at each pulse (clock or date) to determine whether the pulse defines the end of a clock period or is an intervening digit representing pulse.