Patent ID: 8831908

Claim:
A signal processing apparatus configured to process a signal output from a rangefinder, the rangefinder comprising: a light emitting unit configured to output a pulse measurement beam to a measurement target space through an optical window; and a light receiving unit configured to detect a reflected beam reflected from a target measured object present in the measurement target space and to output a reflection signal corresponding to the reflected beam; the signal processing apparatus comprising: a differential processing unit configured to differentiate the reflection signal output from the light receiving unit; a waveform determining unit configured to determine whether the reflected beam includes a plurality of overlapping reflected beams reflected from a plurality of measured objects including the target measured object based on a rising characteristic and a falling characteristic of a first-order-differential reflection signal obtained by first order differential of the reflection signal by the differential processing unit and based on a rising characteristic of a second-order-differential reflection signal obtained by second order differential of the reflection signal by the differential processing unit; and an arithmetic unit configured to, in response to a determination of the waveform determining unit, calculate and output a distance to the target measured object based on the reflection signal.