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Wavelets And Its Applications In Ultra-wide Band Radar

Posted on:2001-11-09Degree:DoctorType:Dissertation
Country:ChinaCandidate:J Y ChenFull Text:PDF
GTID:1118360002951580Subject:Circuits and Systems
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Ultra-wide band Radar is one of the trends in modem Radar technology because of its ability in super-resolution. Wavelets analysis is a promising approach to process ultra-wide band Radar signal. The main research works of this dissertation are aimed at the applications of wavelets in ultra-wide radar, including: the data acquisition technology of ultra-wide Radar signal by using multi-channel structure, the design of channel dropping filters in ultra-wide Radar receiver, the pulse compression technology under the multi-channel structure, the design of quadrature mirror filters based on the criteria of minimum frequency bandwidth, the time delay estimation based on wavelets analysis, the research of wide-band signal model. The main achievements of this dissertation can be summarized as follows: (1) In the research of data acquisition of ultra-wide Radar signal, the decomposition and reconstruction methods of orthogonal wavelets and biorthogonal wavelets are derived under unconventional conditions in which one channel is odd sampling and the other is even sampling. The conditions of the filters that should be satisfied are also derived. By analyzing the transformation structure of orthogonal wavelets and biorthogonal wavelets, the data acquisition method based on multi- channel structure is proposed. The compensation method is discussed, and the design method of compensation filters is also derived. (2) In the research of channel dropping filters, a new method is proposed by approaching Z with all pass filters. The channel dropping filters can then be designed by transforming digital filter (quadrature mirror filters or biorthogonal filters) into analog filters. The filters designed with this method is stable, and can be used to perfectly reconstructing signal in multi-channel data acquisition systems. (3) In the research of multi-channel pulse compression technology, the influence of the channel dropping filters is discussed, and the pulse compression method is derived. It shows that if the data acquisition structure and channel dropping filters in chapter 3 and chapter 4 are used, the error that may be introduced by channel dropping filters can be avoided. It also shows that data interpolation methods should be used in order to achieved better performance. (4) In the research of the design of quadrature mirror filters, the method based on the criteria of minimum frequency bandwidth is proposed. The research is performed under conventional conditions in which two channel are both even sampling, and unconventional conditions in which one channel is odd sampling and the other is even sampling. The design results are given. In order to get low side-lobe filters, the optimization method is discussed. The design results are given by using optimization. It shows that the optimization method is effective. (5) In the research of time delay estimation in ultra-wide band Radar, a time delay estimation method based upon the multirate theory in wavelets analysis is proposed. In this method, time delay estimation is performed by decomposing and reconstructing signal in different levels and estimating time delay with least square method. There is no request for the characterization of signal and noise in the method. It is suitable for the time delay est...
Keywords/Search Tags:Ultra-wide band Radar, Wavelets theory, Data acquisition, Time delay estimation, Model
PDF Full Text Request
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