Research On The Execution And Experiment Of Electrocircuit System In Parametric Array Of Transient Signals

The transient signal pulse modulation parametric array is a single frequency waveemitted and nonlinear interaction between different frequency components. So the transientparameters signal to be obtained. By contrast, the transient signal parameter has manyadvantages, including low frequency, high directivity without side-lobe, high conversionefficiency, and the simple way to launch. The difference frequency wave directivity andtransient characteristics of parametric array are studied based on the basic theory of transientparametric array. The impedance matching circuit of launching system and the filter circuit ofreceiving system are designed. The results of water tank experiment show that theperformance of those circuits is suitable. Main research contents of the project include thefollowing aspects:1、 Nonlinear wave equation is derived based on the theory of nonlinear acoustics.Willem Tver (Westervelt) theory of parametric array is introduced. The difference frequencywave directivity and transient characteristics of parametric array are studied based on thetheory of Berkshire Tai (Berktay) far-field solution, which provide theoretical basis for theidentification of pseudo-second sound.2、The passive LC filter was designed to restrain high strength original wave accordingto transient characteristics of parametric array. The band-pass filter was designed to increasesignal-to-noise ratio of second-wave signal based on MAX274. The results of experimentshow that the performance is up to design requirement.3、 Impedance matching boxes which used in launching system of transient signalparameter array are designed based on transmitting transducer impedance characteristicscurve. The results of experimental show that the performances of impedance matching boxesare in agreement with design requirement.4、Pseudo-second sound effect the second sound when the second sound be tested andused in parametric array experiment of sound. Cause of pseudo-second sound in parametricarray is researched. And several methods for inhibition of pseudo-second sound are presented.The method of identification pseudo-acoustic based on secondary characteristics isintroduced. According to the results of theory and experimental, we can confirm that thesecond sound is obtained in the experiment.