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Orthogonal waveform designing method for formation flying satellites SAR (synthetic aperture radar)

A design method and quadrature waveform technology, applied in the waveform design field of formation satellite SAR, can solve the requirements of increasing bandwidth, Doppler mismatch and other problems, reduce autocorrelation side lobes and cross-correlation peaks, and improve spectrum utilization. rate, the effect of reducing Doppler mismatch

Inactive Publication Date: 2012-07-04
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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Problems solved by technology

Orthogonal waveforms are realized by frequency division, which greatly increases the bandwidth requirements of the system, and the quadrature waveforms realized by phase encoding will cause a large Doppler mismatch

Method used

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  • Orthogonal waveform designing method for formation flying satellites SAR (synthetic aperture radar)
  • Orthogonal waveform designing method for formation flying satellites SAR (synthetic aperture radar)
  • Orthogonal waveform designing method for formation flying satellites SAR (synthetic aperture radar)

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Embodiment Construction

[0028] The following is a specific implementation method for realizing the present invention.

[0029] The specific implementation process of this method will be described below through an example.

[0030] Suppose the formation satellite is composed of four satellites, and the energy of the satellite’s transmitted signal is required to be 1, the bandwidth B≤32MHz, the time width T≤4μs, and the Doppler f of the observation target d ≤180kHz, the waveform design process is as follows:

[0031] 1) Generate the chirp signal according to step 1, as shown below:

[0032] S L ( t ) = 1 4 × 10 - 6 · exp ( j 8 × 10 12 × π t 2 ) -4×10 -6 ≤t≤4×10 -6 (6)

[0033] 2) According to the second step, the chirp signal is divided into 128 equal parts to generate 128 sub-pulses, and at the same time phase-encoded (in this example, a randomly generated two-phase encoding is used for explanation) to generate each satellite transmissi...

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Abstract

The invention relates to a waveform design for a formation flying satellites SAR (synthetic aperture radar), and provides an orthogonal waveform designing method which is used for carrying out phase encoding for linear frequency modulation (LFM) signals. The orthogonal waveform designing method includes generating a linear frequency modulation signal at first, dividing the linear frequency modulation signal into N parts according to equal time intervals to form N sub-pulses, carrying out random phase encoding for each sub-pulse by M times according to the number M of the formation flying satellites, establishing an ambiguity function expression, calculating cluster tolerance xi meeting formation flying satellite synthetic aperture radar Doppler mismatch, finding out a critical N value meeting requirements by the aid of a searching comparison method, finally selecting energy and functions which are in autocorrelation and cross-correlation as cost functions, namely fitness functions in genetic algorithm, searching code values of phase encoding of the various sub-pulses by the aid of the genetic algorithm, and finding out orthogonal waveforms after optimization at last. The waveforms have low autocorrelation side lobes, cross-correlation peak values, bandwidth occupation ratio and Doppler mismatch, and excellently suppress echo signal interferences among different space-borne SARs.

Description

Technical field [0001] The present invention relates to the waveform design of formation satellite SAR, and provides an orthogonal waveform design method by phase encoding the linear frequency modulation (LFM) signal. The designed waveform has lower autocorrelation sidelobes and cross-correlation peaks, and lower The high bandwidth occupancy rate and small Doppler mismatch can well suppress the echo signal interference between different spaceborne SARs. Background technique [0002] Synthetic Aperture Radar (SAR) of formation satellites is a new concept radar proposed in recent years. Each formation satellite is equipped with autonomously controlled and relatively independently operated radar equipment, and through the cooperative work between formation satellites and between sub-radars. , Formation control and other tasks (such as SAR, GMTI and InSAR), is a space-based radar system with powerful functions. Formation satellites SAR use multiple small satellites to form a formati...

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Application Information

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IPC IPC(8): G01S13/90
Inventor 宗竹林张磊朱立东胡剑浩辛凯
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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