Abstract: A method and apparatus for improving the accuracy of laser ranging finding. The time difference obtained from laser range finding is converted into a voltage signal by a linear charge circuit with constant current and then digitized into a digital value by an analog to digital converter. A self calibration method is used to compensate for the thermal effect in a user's environment and improve the precision of the distance measurement obtained from the laser range finder. The self calibration method includes measuring two voltage values by using two correction pulses with known width after the laser range finder is initialized. The standard values in response to the two correction pulses are used to calibrate the measured data for obtaining a correction gain and a correction level. An instant distance value measured from a target can be calibrated by the correction gain and level to achieve higher precision of range finding.

Abstract: A method and apparatus for reducing the noise of a laser range finder. The laser range finder includes a high voltage silent circuit, a logarithmic amplifier and a sun noise averaging amplifier. The high voltage silent circuit shuts down the switched power supply controller of the high voltage power supply to reduce the noise coupled from the high voltage power supply when the receiver of the laser range finder is in a receiving mode. The logarithmic amplifier provides dynamic gain control for the receiver to avoid signal saturation and improve the signal to noise ratio of the received signal. The sun noise averaging amplifier provides an amplified average sun noise which automatically adjusts the threshold voltage of detecting the distance signal from a target.