Broadband Radiation Noise Measurement Array DSP Beam-forming Technology

With the development of vibration and noise reduction technology, radiated noise of underwater targets reduced year by year, making stealth capability of underwater targets significantly enhanced . And how to measure the radiation noise, and then evaluate its stealth performance has become a problem. The paper analyzed necessary conditions of radiated noise measurements by using of underwater large structures with linear array, combined theory broadband beamforming, vector signal processing method and high-speed DSP computing platform, presents a large-scale structure for underwater low-E Realization method of noise measurement, the main contents are as follows1.This paper described the underwater radiated noise measurement method by vertical array, and analyzed the characteristics of this method. After reviewied the basis of conventional beamforming method, the conventional methods of measurement of underwater radiated noise in the measurement of the drawbacks were analyzed.2.This paper briefly described the principle of the linear model nested array principle and extended this model. The basic principles of constant beamwidth beamforming on an octave was derived. And the method of formation of constant beamwidth on the direction of the spindle and non-spindle and the simulation of the theory were given. Then the forming method of constant beamwidth on several octave bands was described briefly. Since the gain of the line array and main beam direction and array size were related, this paper analyzed the measured array gain in three cases and shows the measurement limit state.3.This paper described the general method of time delay beamforming. The problem of digital signals processing that the signal could not be accurate delayed when it is focused was solved. First, the principle of FIR filter and the main steps to establish FIR filter to be used for constant beamwidth beamforming were described. Then a simulation of time delay beamforming was conducted on this basis. Finally, the simulation results of spindle and non-spindle direction beamforming were analyzed.4.This paper analyzed the results of three kinds of linear beamforming affected by the flow and presents the appropriate solutions.5.This paper realized the beamforming algorithm in an octave on the DSP chip platform. And the experimental data on the lake was analyzed with the front method.Theoretical and experimental results show that:linear nested array constant beamwidth beamforming method of vertical linear array based on DSP processor can guarantee a constant width of the main beam, and it's an effective method to solve the problem of measuring underwater radiation noise target.