DEVICE FOR DETERMINATION AND CLASSIFICATION OF OBJECTS ACCORDING TO THEIR ACOUSTIC IMPEDANCE Russian patent published in 1994 - IPC

FIELD: acoustic location systems. SUBSTANCE: probe pulse having high-frequency amplitude-modulated constituent and modulation-frequency constituent is emitted into water by double-resonance transducer. The same transducer receives signals that were reflected from probed object. Then signals through receipt/transmit commutator enter inputs of selective amplifiers tuned to modulation frequency and carrier correspondingly. Converted signals after amplification, detection and clipping enter inputs of phase detector. Phase of reflected wave having carrier frequency depends on ratio of acoustic impedance of probed object and environment. Phase of envelope does not depend on this ratio. So, polarity of pulse at output of phase detector depends on acoustic impedance of probed object. This simplifies classification performed by means of oscilloscope. EFFECT: increased reliability of classification. 2 dwg