Hughes Electronics Corporation

Robert A Kuehn

Charles E Nourrcier

Laser range finder circuitry including an avalanche photodiode detector, a capacitor for storing a detector bias voltage, and a transimpedance amplifier for amplifying the detector signal. The capacitor is charged in response to a first control signal by a circuit employing first and second field effect transistors and is discharged in response to a second control signal by a circuit employing a third field effect transistor. An overload protection circuit including a single diode is provided to accommodate excessive charge created by backscatter upon initial laser firing. A temperature sensor is further provided to develop a temperature signal which may be monitored to adjust the detector bias voltage and other parameters so as to permit use of an associated laser range finder over a wide range of temperatures.

Temperature compensated APD detector bias and transimpedance amplifier

A laser range finder receiver for detecting a return pulse and providing an output signal indicative thereof and a single-chip microcontroller for controlling receiver operation and, in particular, for automatically recalibrating the receiver. The receiver is responsive to up and down current control signals from the microcontroller to adjust the bias of an APD photodetector. An offset voltage and receiver false alarm rate are monitored with no light on the photodetector while a calibration voltage is adjusted to recalibrate the receiver. The microcontroller further monitors photodetector temperature via a temperature sensor, and can perform APD bias adjustment and receiver recalibration in response to temperature changes, providing operation over a wide temperature range.

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El Segundo, CA, United States of America

Robert A Kuehn