GB1115431A - Improvements in peak-detectors - Google Patents

Abstract

1,115,431. Peak voltage detectors. NORTH AMERICAN AVIATION Inc. June 2, 1965 [June 4, 1964], No. 23587/65. Heading G1U. A peak detector providing an output representing the maximum deviation of an input applied at 14 in one sense from a datum, or if the input is solely in the other sense, the minimum deviation from the datum. incorporates a summing network 10 which sums the input and output of the detector, and a half wave rectifier 19 coupling the input to an integrating circuit 18 via an inverting amplifier 20 in such a way that only signals of a given polarity are integrated to provide the detector output. Independently operated clamping circuit 26, 22 are connected to the summing and integrating circuits respectively to restore the outputs thereof to predetermined reference levels. The detector may be used in conjunction with a terrain avoidance radar to respond to peaks in the output from such a system. Each radar pulse is initiated by a trigger, which is also applied to the circuit 28 to produce a pulse after a delay time set by unit 30 to render the detector operative, by removing the earth connection to the junction 13 for the time during which the returned radar signal is received. The integrated output (waveform 39) and the input to the detector 35 are summed for the gating period to form waveform 37. This is passed via emitter follower 16 to clamp circuit 19, to derive the waveform 38. This is amplified and inverted before being passed to the integrator 18. The integrator is initially charged to a positive voltage in response to the system trigger, which closes switch 23 for a short period to raise capacitor 18 to a constant positive reference. Thereafter, in response to the inverted waveform 38, the integrator output takes the form shown in waveform 39. The steady negative signal between operating periods represents the peak waveform being detected. The system may be used to provide an observable output for manual control of e. g. an aircraft or may be used to control an autopilot. In such a control system, the output from the detector shown is filtered and passed through a low pass filter to a second similar detector which is gated in accordance with a required azimuth range so that only peak signals in the range are detected. The detected signals are passed to the autopilot. Conventional transistorised circuitry for use as the detector is described, Figs. 5 and 6 (not shown).