Patent ID: 8603002

Claim:
An apparatus for calculating microvibration feature quantity, comprising: a beat signal receiver that receives a beat signal output from a Doppler sensor, the Doppler sensor radiating a radiation wave at a predetermined frequency to a body and sensing part of the radiation wave reflected by the body to output the beat signal at a frequency associated with a difference in frequency between the radiation wave and the reflected part; a frequency converter that transforms the received beat signal to a corresponding frequency-domain signal; and a beat signal feature quantity calculator which uses the frequency-domain signal to derive a beat signal feature quantity exhibiting an abrupt change with respect to time of a vibration velocity of the microvibration, said beat signal feature quantity calculator deriving the beat signal feature quantity by calculating a second-order derivative with respect to time of the vibration velocity and emphasizing the microvibration from a temporal change of the vibration velocity.