Research Of Combined Acoustic Receivers

The directivity of underwater acoustic receiver is very important for the underwateracoustic system, which directly determines sonar resolution accuracy. The directivity ofconventional acoustic array is limited by its own aperture, and the problem which needs to besolved is how to improve the sensor directivity while maintain its small size at the same time.Based on the vector hydrophone technology, the combined acoustic receivers wereresearched here to implement high directivity and small size underwater acoustic receivers.This thesis started with the Taylor power series expansion of sound field, and introducedthe concept of acoustic dyadic and combined acoustic receivers here, and the directivitycharacteristics of combined acoustic receivers were also analyzed theoretically. Here, thethesis also analyzed the influence to combined acoustic receivers directivity, brought by thefinite difference approximation error and vector hydrophone misalignments.In this paper, a acoustic combined acoustic receivers were assembled with four acoustichydrophones, two spherical vector hydrophones as well as a capsule dome, which could beused to achieve the measurements of acoustic information of scalar, vector and dyadic soundfield. The hydrophones with small piezoelectric ceramic tubes as the transducer components,had a size of φ20×13(mm), and their sensitivity are-217dB~-213dB(0dB=1V/μPa). Thevector hydrophones had the pressure sensitivity level between-194dB to-192dB(0dB=1V/μPa,500Hz), which had a cosine directivity and φ40(mm)diameter. The capacitivesilicon micro-accelerometers were used as sensitive elements of vector hydrophones. Thecapsule dome was made by the polyurethane material to ensure good acoustic transparency.Finally, the results of the combined acoustic receivers directivity measurements show that thedyadic channel had a narrow beam, reaching the requirements for high directivity and smallsize.