The Detection Characteristic's Study Of Vector Transducer In The Isotropic Noise Field

The signal detection technique with vector hydrophone is one of the new technique in the acoustic science. It has wide prospect in weak signal detection and measurement for low -level noise target. It is called "Acoustic technique in the twenty-one century". The signal detection technique with vector hydrophone measures acoustic vector components comprising the direction information comparing to the traditional hydrophone .The acoustic energy flux detector based on vector hydrophone using counteractive technique of spacial acoustic energy flux, can obtain spatio-temporal gain proportion with time-bandwidth product. Comparing to the acoustic pressure detector it is the main advantage of the signal detection technique of vector hydrophone.Under ideal condition, one vector hydrophone can obtain infinite gain, if energy flux of noise can be counteracted in the entire space. But in practice, The acoustic energy of noise is only to be counteracted finitely, because existing anisotropic component in the noise field. Consequently, the gain of detection of the vector hydrophone is reduced, and the detective capability of vector hydrophone is limited.In the thesis, the model of anisotropic noise field is established based on isotropic ingredient in the noise field. The influence of isotropic noise field on detective capability of vector hydrophone is discussed. The contents of the thesis is:(1) Horizontal acoustic energy flux detector is maximum likelihood detector and maximum likelihood estimator in the sea surface noise field. The gain of horizontal acoustic energy flux detector is proportion with square root of time-bandwidth product; CRB of DOA is decreased with time-bandwidth product increased and with signa]-noise ratio increased.(2) The gain limitation of particle velocity and acoustic energy flux in the sea surface noise field and half-isotropic noise field is discussed based on orientation-exponent theoretic.(3) The cohere-function evaluation Standard of half-isotropic noise field is established based on space-correlation of noise field.(4) The method of time-domain self-adaptive pretreatment is discussed based on correlation of signal and noise.By the experiment at result, the influence of isotropic noise field on detective capability of vector hydrophone is tested.