Research On Target Parameter Estimation Algorithm For Wideband Distributed Coherent Radar

The distributed coherent aperture radar have many advantages over the large phased array radars, for instance, strong survival ability, The distributed coherent aperture radar is a system composed of cooperating radars with smaller detecting range, by working together they can have a large detecting range, since each cooperating radars is much more flexible, and hard to be destroy by the enemy; obvious economic benefits, compared with the large phased array radars, the distributed coherent aperture radar is much cheaper, and because of its flexibility it can deploy rapidly wherever needed; High angular resolution, the distributed coherent aperture radar has high angular resolution, and it can match with the seeker, realize precise orbit determination and velocity recognition; good extensibility, we can improve the detecting range by adding cooperating radar numbers; less disturbance, the distributed coherent aperture radar can suppress clutter restrain electromagnetic interference, and because of the measurements of each cooperating radar are uncorrelated, the measuring error caused by the atmosphere can be reduced by taking the average.This dissertation is addressed on parameter estimation of target, switching conditions of MIMO mode and TR mode, and multi-target detection in TR model. The work of this dissertation can be summarized as the following three aspects:1.Introduced the realization of the distributed coherent aperture radar, and analyzed the SNR gain in each mode. Then discussed the influence of the non-ideal orthogonality, and a a solution is given. Analyzed the performance of a parameter estimation method in MIMO mode by simulations. The results show that this method yield have many grating lobe with, In order to estimate the parameter right with a high probability, SNR need to be large.2.Introduced a non parametric and hyperparameter, free-weighted, least squares based iterative adaptive approach to estimate parameters. This method has high parameter estimation precision, and work well in the low SNR situation. Compared with other high resolution algorithm such as Capon, MUSIC, this method make no demands on the snapshot number, it can work with a few snapshots(even one).Then give the switching conditions of MIMO mode and TR mode.3. In the TR mode, an approach is presented to detect the far-field multi-targets. By analysing the echo signal model, we found that the tradition keystone transformation can be used to coherent process the echo signals received by multi-radar. Because of the distance between each radar is much more the half of the wavelength, there will be ambiguity in the spatial domain, and each target may have different ambiguity numbers, traditon keystone transformation could not work well under this circumstance, so we present another method called IAA-keystone transformation.4.The problem of target delay and phase estimation for high SNR is researched. Firstly, introduced Capon method and APES method to estimate the delay and phase, then we realized Capon method used the data smooth process, and do not take full advantage of the signal, in this case we give another sparse signal representation method,BLOOMP method to estimate the time delay. With the high precision time delay estimation and the phase estimation, we proposed the modified phase –derived range method, this ranging method has high-precision, so we can use the estimation and the geometrical relationship of the cooperating radars and the target, to get the angle information of the target, this method will not suffer from the angle ambiguity, and we can find that this method has high angular resolution by simulations.