Research On Detection System For Multi-parameter Joint Estimation Of Underwater Moving Targets

The ultrasonic detection of underwater moving target is a very important project, it has a great application value in military and civil field. In traditional, due to position detection and motion detection use different algorithms in motion target detection system, existing mutual interference of the parameter estimation which lead to the parameters estimation having coupling relationship between of moving targets distance and velocity. So it is necessary to study the joint estimation about the position parameter and motion parameters of the moving target.Because the parameters such as distance, speed and azimuth affect the value of frequency of the signal, via transmitting chirp signal and analyzing the changes of frequency of the received signal, we can inverse parameters such as distance, speed at the same time. Its characteristic is that transforming multiple parameters who are detected into the frequency variation function, which can get from the echo signal demodulation, so this text spread the discuss based on the subject of the frequency estimates, including center frequency and adjustable frequency of chirp signal.The main contribution of this text is as follows:1. According to the shortcomings of the optimal order of FRFT need to search in the two-dimensional plane peak time-consuming long and poor noise immunity, this text propose an improved algorithm which based on central moment and adaptive step length. This algorithm take short time and do not sensitive to noise can accurately estimate the optimal order in-10 d B SNR environment. In the strong noise environment, This algorithm even can by changing the order of methods to improve the noise performance.2.This text derive the doppler echo signal model of underwater moving target, when transmitting signal is chirp signal and transforming multiple parameters who are detected into the frequency variation function. The feasibility of this method is proved by simulation and experiment, improving the algorithm of MUSIC which is used to estimation DOA let it adapte to the LFM singal.3. This text puts forward the concept of intermittent chirp signals whit multi-slope. On moving target trajectory estimation, we need transmit periodic chirp signal, and at the receiving end receives the echo signals containing a number of different frequency and different time delay of chirp signal.In order to be able to differentiate the chirp signals’ peak of different orders of FRFT of the echo signal better, this text propose the concept of intermittent chirp signal with multi-slope, via transmitting different slope of chirp signals each time to improve the estimation precision of the moving target trajectory, and verified the effectiveness of the method by MATLAB simulation.4. With the help of a national mobile ultrasonic detecting engineering technology research center of the underwater ultrasonic detection device, this paper joint estimation method is verified by experiment in the distance the feasibility.