Open loop correction method for LFMCW SAR nonlinear error

A non-linear error and open-loop correction technology, applied in radio wave measurement systems, instruments, etc., can solve the problems of low calculation and robustness, and achieve the effect of simple implementation, low algorithm calculation and improved signal pulse compression performance

Active Publication Date: 2015-03-25
NAT UNIV OF DEFENSE TECH
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Problems solved by technology

However, the existing FM nonlinear correction processing method under open-loop conditions cannot take into account low computational load and robustness, therefore, it is necessary to study a new LFMCW SAR nonlinear error correction method to solve this contradiction

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  • Open loop correction method for LFMCW SAR nonlinear error
  • Open loop correction method for LFMCW SAR nonlinear error
  • Open loop correction method for LFMCW SAR nonlinear error

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Embodiment Construction

[0036] The present invention will be further described below in conjunction with the accompanying drawings.

[0037] figure 1 It is a principle flow chart of the present invention. As shown in the figure on the left, by collecting the VCO signal of LFMCW SAR with frequency modulation nonlinear error, it is analyzed for frequency modulation nonlinearity, that is, the error coefficients of each order are fitted, and the fitted error coefficients of each order are substituted into the frequency modulation nonlinearity An error correction model, thereby obtaining corrected predistortion voltage data, and judging whether the predistortion voltage is the optimal predistortion voltage by judging the iteration termination condition. As shown in the figure on the right, assuming f (n) (t) is VCO at input voltage u (n) The frequency curve under the excitation of (t), through the analysis of the curve, the coefficients of each order are fitted i=0,1,2,3,4,5. by the coefficient Th...

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Abstract

The invention provides an open loop correction method for an LFMCW SAR nonlinear error. According to the technical scheme, an LFMCW SAR VCO signal containing the frequency modulation nonlinear error is collected and subjected to frequency modulation nonlinear analysis, in other words, fitting is performed on all-order error coefficients, the all-order error coefficients having been subjected to fitting are substituted into a frequency modulation nonlinear error correction model, and therefore corrected pre-distortion voltage data can be obtained, and whether pre-distortion voltage is optimal pre-distortion voltage or not can be judged by judging the iteration stopping condition. The correction method is easy to implement, computation burden of an algorithm is low, and pulse compression performance is remarkably improved after correction.

Description

technical field [0001] The invention belongs to the technical field of SAR (Synthesized Aperture Radar, Synthetic Aperture Radar) signal processing, in particular to a method for correcting and processing LFMCW (Linear Frequency Modulated Continuous Wave, Linear Frequency Modulated Continuous Wave) SAR FM nonlinear signals. Background technique [0002] LFMCW SAR usually uses linear frequency modulation continuous wave as the transmission signal, which is generated by VCO (Voltage Controlled Oscillator, voltage-controlled oscillator), DDS (Direct Digital Synthesizer, direct digital synthesizer) and DAC (Digital-Analog Converter, analog digital conversion) and so on. Compared with linear frequency modulation signal generation methods such as DDS and DAC, VCO has the characteristics of high frequency point, wide bandwidth, and ease of use. However, VCO has the problem of frequency modulation nonlinearity during operation, and the nonlinear error will cause the compressed signa...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01S7/40
CPCG01S7/40
Inventor 何志华易天柱侯振宇董臻张永胜黄海风余安喜何峰孙造宇金光虎张启雷杜湘瑜
Owner NAT UNIV OF DEFENSE TECH
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