METHOD REGISTERING ACOUSTIC WAVE Russian patent published in 2002 - IPC

FIELD: systems detecting objects emitting acoustic signals. SUBSTANCE: method registering acoustic wave consists in action of acoustic field created by moving object on transducer manufactured in the form of extended optical cable, in formation of optical signal and its feeding into light guide of optical cable, in its transmission over optical cable, in conversion of optical signal to electric signal at receiving end of optical cable, in conducting preliminary spectral analysis of electric signal, in measurement of its amplitude and in determination of direction of propagation of acoustic wave. In addition transmitted optical signal is modulated by external discrete signal of known structure, optical signal received after conversion to electric signal is filtered , time sampling and amplitude quantization of received signal are conducted, its amplitude is measured and compared with THRESHOLD value specified in accordance with Neumann-Pirson criterion. Moments of initial and final time of excess by signal of THRESHOLD values t_i and t_f correspondingly, time moment t_m corresponding to minimal level of signal and time moment t at which Doppler frequency in signal spectrum equals zero are registered. Distance L from receiving end of optical cable to point in which moving object creating acoustic wave crosses optical cable is computed by formula , where c is speed of propagation of light in light guide. Then Doppler frequency is measured and coordinates of points of entrance and exit of moving object from zone of sensitivity of transducer at time moments t_i and t_f correspondingly are computed. Trajectory of movement of object is extrapolated by results of measurement of amplitude of signal of Doppler frequency in two or three points at time moments t_i,t_∂,t_f correspondingly and direction of propagation of acoustic wave is determined. Time scale of highly stable synchronization signals extracted from received discrete signal is formed to register above-mentioned time moments. EFFECT: simplified process of registration of acoustic wave.