Patent ID: 7184131

Claim:
A multifunction rangefinder, comprising: a power supply; a distance measurement unit capable of short and long distance measurements, coupled to the power supply to transmit a light beam to a target, receive reflected light from the target, and output a distance measurement signal; a compass measurement unit coupled to the power supply to measure terrestrial magnetism, generating a compass measurement signal; an altitude measurement unit coupled to the power supply to measure atmospheric pressure, generating an altitude measurement signal; a microprocessor calculating a distance between the target and the distance measurement unit and altitude according to the distance measurement signal and the altitude measurement signal respectively, and determining the direction to of the target according to the compass measurement signal; and a display unit coupled to the microprocessor to display the calculated distance between the target and the distance measurement unit, the calculated altitude and the determined direction to of the target, wherein the distance measurement unit comprises: a transmitter transmitting the light beam to the target; a receiver receiving the reflected light from the target and outputting a corresponding distance signal; a comparison/gain device receiving and processing the distance signal in a comparison mode or in a gain mode; and a mode switching device selectively switching between the comparison and gain modes of the comparison/gain device, wherein the comparison/gain device detects whether a pulse is higher than a reference voltage when the comparison/gain device is switched in the comparison mode by the switching device, and the comparison/gain device amplifies the distance signal to output an amplified signal when the comparison/gain device is switched in the gain mode by the mode switching device.