Patent ID: 7834986

Claim:
A velocimeter comprising: a plurality of photodetectors detecting scattered light in different directions, the light being emitted from a light source and reflected on a moving object; an analog-to-digital conversion unit configured to convert detection signals of the photodetectors into digital form and output a plurality of digital signals; a velocity calculator configured to calculate velocities of the moving object based on the digital signals; an amplitude calculator configured to calculate amplitudes of the detection signals based on the digital signals; a dropout detector configured to detect dropouts of the detection signals based on the amplitudes calculated by the amplitude calculator; a time keeper configured to keep detection times at each of which a dropout has been detected by the dropout detector; a switching-time calculator configured to calculate signal switching times of the digital signals based on the detection times; a storage unit configured to store the velocities, the amplitudes, and the signal switching times calculated from the digital signals; and an output selector configured to select one of the velocities stored in the storage unit based on a result of comparison between the amplitudes and a result of determination as to whether the digital signals are not relevant to the signal switching times, and output the selected velocity.