Non-linear frequency-modulated signal undersampling processing method
A linear frequency modulation signal, nonlinear frequency modulation technology, applied in the direction of radio wave measurement systems, instruments, etc., can solve the problem of large amount of calculation, not suitable for nonlinear frequency modulation signal processing, etc., to reduce the sampling rate of the system, reduce the amount of data transmission and effect of storage
Active Publication Date: 2018-05-08
NAT SPACE SCI CENT CAS
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However, the traditional linear frequency modulation signal deskewing processing method is not suitable for nonlinear frequency modulation signal processing; literature [3] (Mir HS, Wong U K T. Low-rate sampling technique for range–windowed radar / sonar using nonlinear frequency modulation[J]. IEEE Transactions on Aerospace and Electronic Systems, 2015, 51(3): 1972-1979.) proposed a low-rate sampling processing method for non-linear frequency modulation (NLFM), but the calculation of this method is relatively large
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[0049] The non-linear frequency modulation signal under-sampling processing method of the present invention will be described in detail below with reference to the drawings and embodiments.
[0050] The invention provides a method for undersampling a broadband nonlinear frequency modulation signal. Firstly, the broadband nonlinear frequency modulation echo signal is undersampled to obtain a digital echo signal, and then the digital echo signal is mixed with a digital reference signal to complete the digital domain. De-slope, get the narrow-band echo signal after digital de-slope, and restore the broadband nonlinear FM signal by upsampling and linear frequency modulation on the narrow-band echo signal after digital de-slope, and then complete the broadband nonlinear FM signal through matched filtering pulse compression. The invention realizes the under-sampling processing of the broadband nonlinear frequency modulation signal, and at the same time, reduces the sampling rate of ...
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The invention discloses a non-linear frequency-modulated signal undersampling processing method. The method comprises the following steps of step1) using a sampling frequency which is lower than a radar system emission signal st(t) bandwidth to carry out AD undersampling on a radar echo signal s(t) after a down-conversion to base band process; acquiring an undersampling echo signal sp(t); step2) in a digital domain, carrying out frequency mixing on the undersampling echo signal sp(t) and a de-sloping digital reference signal and acquiring a de-sloping digital signal sd(t); step3) carrying outupsampling on the de-sloping digital signal sd(t), carrying out linear frequency modulation on the signal after upsampling and a reference linear frequency modulation signal to recover a broadband echo signal sm(t); and step4) carrying out matched filtering on the recovered broadband echo signal sm(t) and the emission signal st(t), and then carrying out pulse compression to acquire a target one-dimensional distance image. By using the method of the invention, when a distance between a radar and a mapping range is small, broad-band non-linear frequency-modulated signal undersampling processingis realized, simultaneously, a system sampling rate is reduced, and a data transmission quantity and a storage amount are decreased.
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technical field [0001] The invention relates to the technical field of radar (sonar) signal processing, in particular to a non-linear frequency modulation signal under-sampling processing method. Background technique [0002] As a high-resolution imaging radar, ISAR has been widely used in space target detection. In order to obtain more information about the observation area or the observation target, wideband radar usually uses wideband (ultra-wideband) to transmit signals. Compared with the linear frequency modulation signal, the non-linear frequency modulation signal has the advantages of low sidelobe and no need for weighting, so there is no loss of signal-to-noise ratio. It is more and more valued in the application of radar (sonar) systems. However, in the broadband radar system, the broadband non-linear frequency modulation signal has high requirements on the system A / D sampling, storage and transmission equipment, which greatly limits the imaging resolution of the r...
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Login to View More IPC IPC(8): G01S7/41G01S7/539
Inventor 刘加方张云华董晓
Owner NAT SPACE SCI CENT CAS