APPARATUS FOR DIGITIZING NOISY TIME DURATION SIGNALS

摘要

1391532 Transistor pulse circuits GENERAL SIGNAL CORP 23 Oct 1972 [5 Nov 1971] 48672/72 Heading G4H Apparatus for processing time-duration signals (a) containing transient noise portions Tb includes means 18-21 for obtaining a pulse counter representative of the duration of each signal and means 11, 22, to ensure that the transients do not affect the accuracy of the count. Each signal is input (at time To) via a relay 13 and contact 17 to enable clock pulses to pass through a gate 18 to a counter 19, contact bounce being responsible for the transients. The signal passes (T1) via a differentiator 28, 29 to a NOR gate 24 forming part of a monostable circuit 24-27 whose output 31 passes via another differentiator 32, 33 to a second monostable 22 (signals b-f). At time T2 the signal is at level "O" so that a diode 34 conducts to ensure that the positive triggering "spike" of signal f does not reach monostable 22: however, after the second transients (T4) the signal reverts to the "1" level and diode 34 cannot prevent the next positive "spike" from causing circuit 22 to output a latch pulse h to a register 21 and a reset pulse to counter 19. With the above arrangement, the reset and latch pulses are produced only at the end of each signal, and not by each transient. Since the pulses lost during the first transients are to all practical purposes offset by the extra pulses arising from the second ones, the count is effectively the signal length (T0, T3). The time constant of 26, 27 determines the length of the time intervals (T1, T2) and (T3, T4) and is sized to exceed the bounce period adjacent the leading edge of the signal since this is in practice longer than that adjacent the trailing edge.