The Research Of Measurement Of Radiated Noise By Passive Synthetic Aperture Technique

Along with the antivibration noise reduction technology's development, the radiated noise of the submarine large-scale structure is getting lower, so it is impossible to satisfy the metrical request by the conventional noise measurement equipment. The sonar array may obtains higher gain, and may measures the lower radiated noise. However, the linear array has many elements and big volume, therefore it is expensive, and reclaims it discommodiously after deployed.The passive synthetic aperture technology can obtains beam-forming's width and gain perfectly by less elements, also the price is low and the flexibility is good, which opens a new way for the low noise measurement.The paper reviews the principle of convention beam-forming method. Discusses the mechanism of passive synthetic aperture, infers the mathematical model, educes the performance and influencing factor of passive synthetic aperture beam-forming technology by the computer simulation. The paper also gives the output of PSAS under the conditions bases on different parameters of time coherence and the hauling velocity.The paper describes the essential requirements of measure the underwater noise, and analyses the requirements through the noise measurement system to the sonar array, obtains the array parameter of PSAS what is able to apply in the noise measurement. Calculates the algorithms of FFTSA (Fast Fourier transform synthetic aperture) and ETAM (Extended towed array measurements), shows the principle for designing the passive synthetic aperture that uses in the noise measurement. Compares with conventional beam-forming, the paper shows some conclusions: uses the synthetic aperture algorithm, may obtains the array gain and azimuth resolution of large array, may reduces the difficulties of the project, may meet the requirement for measuring the low radiated noise target, has provided the reference for the following research.