GB1312651A - Electronic pulse devices - Google Patents

Abstract

1312651 Differentiating circuits ROBERT BOSCH GmbH 17 April 1970 [19 April 1969] 18354/70 Heading G4G [Also in Division H3] The circuit shown, comprising an integrator 14 and a monostable circuit 11, is used to detect changes in the frequency of pulses 112 applied to an input terminal 12. The pulses trigger the monostable circuit 11 to produce a square-wave output which, in the absence of the integrator 14, would have a mark-space ratio dependent upen the pulse-repetition frequency. Part of the output is fed to the integrator which produces a voltage proportional to the mark-space ratio and compares it with a constant voltage from a source 15. The output of the integrator is fed back to the monostable circuit 11 and used to regulate the pulse length in such a manner that the mark-space ratio tends to a constant value. This constant value is determined by the value of the constant voltage. The resultant signal 113 is fed to output terminal 13. A low-pass filter (which may be omitted from the circuit) converts the square-pulse signal to a virtual D.C. which has a constant value 117 during those periods when the mark-space ratio of the square-pulse output is constant. At times when the p.r.f. of signal 112 is changing, the mark-space ratio will increase or decrease according to whether the p.r.f. is increasing or decreasing and the D.C. signal will increase or decrease by an amount 118 or 119 proportional to the rate of change. The duration of the increase of D.C. output is an indication of the duration of the p.r.f. variation. The pulses 12 may represent the velocity of a vehicle wheel and the D.C. output used to detect acceleration and deceleration.