Patent ID: 7508497

Claim:
A rangefinder configured to determine a range to a target by measuring a flight time of a beam traveling between the rangefinder and the target, the rangefinder comprising: a transmitter configured to emit the beam towards the target; a receiver configured to detect a reflection of the beam from the target, the receiver comprising: a photodiode configured to generate a current signal proportional to the received reflection; a transimpedance amplifier configured to receive the current signal and to generate a voltage signal proportional thereto; noise reduction circuitry configured to reduce noise present in the voltage signal by limiting the voltage signal relative to a first voltage level, the first voltage level selected according to a methodology of reducing said noise in said voltage signal; a comparator configured to indicate when the noise-reduced voltage signal exceeds a second voltage level, the second voltage level selected above an expected noise in the noise-reduced voltage signal, thereby confirming that when said noise-reduced voltage signal exceeds said second voltage level, said received reflection comprises a desired reflection; one or more filters configured to remove noise components from the voltage signal; and an amplifier configured to amplify the voltage signal, wherein the amplifier is further configured to set a mean value of the voltage signal to the first voltage level; and a processor configured to convert the flight time of the beam into a range measurement when the comparator indicates the noise-reduced voltage signal has exceeded the second voltage level.