Patent ID: 8649244

Claim:
A target searching device for searching presence or absence of a target within a propagation space, which searches the target by using, from a backward scattering wave scattering backward from the target and a forward scattering wave scattering forward from the target, the forward scattering wave, and by using the forward scattering wave and a traveling wave from a sound source making incident on the target within the propagation space, the device comprising: a sound source which transmits a sound wave that is a probe signal into the propagation space; a transducer array placed in an area to receive the forward scattering wave that is a data signal which scatters forward from the target when present within the propagation space; a subtraction processing device which performs subtraction processing for subtracting the traveling wave that is the probe signal directly traveling from the sound source towards the transducer array when the target does not exist within the propagation space from a mixed wave of the forward scattering wave that is the data signal and the traveling wave that is the probe signal directly traveling from the sound source towards the transducer array so as to separate a difference obtained by the subtraction processing as the forward scattering wave that is the data signal; a passive-phase conjugate processing device which performs passive-phase conjugate processing on the forward scattering wave separated by the subtraction processing device so as to generate a passive-phase conjugated signal of the forward scattering wave; an autocorrelation processing device which performs autocorrelation processing on the traveling wave that is the sound wave transmitted from the sound source, which makes incident on an arbitrary position within the propagation space by having the sound source as a reference position so as to generate an autocorrelation processed signal of the traveling wave; and a correlation device which judges presence or absence of the target from a similarity between the autocorrelation processed signal and the passive-phase conjugated signal.