Parametric Receiving Array And The Technique Of Signal Processor

As the development of science technology, along with the developing of the ocean resources requirements, much more attention has been taken to the exploitation prospect and the important strategy position of the ocean. The parametric acoustic receiving array not only can detect useful weak signal under strong noise background, but also has poignant directivity, which are the superiorities that conventional array can’t compare. The research and application of parametric receiving array are taking more attention. This dissertation is going to make a systemic research of parametric acoustic array based on the previous research. Some characteristics of parametric receiving array have been discussed, and some experiments have been operated in the anechoic tank. Designed a parametric receiving array based on lock-in amplifier technology. The main contents of the study include:1. Based on the theory of nonlinear acoustics, the theory which makes parametric acoustic array generating was researched detailed and systematically, along with the principle. Both the history and the development were introduced briefly in the paper.2. Some characteristics of parametric acoustic receiving array have been researched. The directivity of the parametric receiving array in end-fire direction is satisfactorily, and is narrow beam in both horizontal and vertical direction. The directivity is related to the medium, which determine the performance of the directivity. In the practical application of parametric receiving array, the conversion efficiency of original wave energy to the difference-frequency wave energy is very low, which is the main problem that parametric receiving array faced with. This dissertation from the derivation theory, analyses the relevant parameters of parametric array conversion efficiency. Some improvement measures are proposed.3. Two kind of non-water medium have been researched. Discussed the reason of improving parametric receiving array conversion efficiency by micro-bubbles layer and silicon rubber respectively. It also compares some performances between parametric receive in water and silicon rubber under the same condition.4. Designed the test system of parametric receiving array. Including signal transmitting part, receiving part and processing part. The parametric receiving equipment is also given. Parametric receiving array in water and in silicon rubber have been tested in anechoic tank respectively.5. Designed a kind of parametric receiving array, which uses the lock-in amplifier technique to suppress the residual pump signal. It is capable of making the difference-frequency wave matches its theory value, and detecting the frequency of unknown signal source. The performance between traditional parametric receive system and the designed parametric receive system were also compared and analyzed by simulation.