Practical frequency domain compression bit allocating method for original data of space-borne squint SAR (Synthetic Aperture Radar)
A technology of bit allocation and raw data, applied in the direction of using re-radiation, reflection/re-radiation of radio waves, measuring devices, etc., can solve the problem of two-dimensional spectral energy distribution tilt and so on
Active Publication Date: 2013-04-17
INST OF ELECTRONICS CHINESE ACAD OF SCI
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[0005] The purpose of the present invention is to disclose a practical frequency-domain compression bit allocation method for spaceborne squint SAR raw data, to solve the problem that the squint SAR Doppler center is non-zero and the energy distribution of the two-dimensional spectrum is inclined along the azimuth direction
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[0030] The invention provides a practical frequency domain compression bit allocation method for the original data of spaceborne squint SAR. The bit allocation scheme is determined by the transmission data rate, the number of blocks and the distance-direction oversampling coefficient; Perform range and azimuth block division, calculate and sort the average magnitude of each block; allocate different number of bits to each block of data according to the magnitude of the average magnitude and the bit allocation scheme, and do not need to estimate the Doppler center.
[0031] The specific operations include: calculating the allocation ratio of different compressed bits according to the known transmission data rate, number of blocks and range oversampling coefficients; according to the range oversampling rate, transmitting the two-dimensional spectrum of the squint SAR echo in the range direction The part other than the bandwidth is set to zero; the spectrum is divided into blocks ...
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The invention discloses a practical frequency domain compression bit allocating method for an original data of a space-borne squint SAR (Synthetic Aperture Radar) and relates to a data compression process. The practical frequency domain compression bit allocating method comprises the following steps: confirming a bit allocating scheme according to a transmission data rate, a block number and a distance-oriented over-sampling coefficient; at the bit allocating moment, respectively calculating data amplitude mean values of all blocks and sequencing in descending order; and omitting the doppler centre estimation with a large computation quantity, distinguishing high-low energy areas according to the size of the data amplitude mean value of all blocks, and performing bit allocation. On the premise of meeting the demand of a transmission data rate, the practical frequency domain compression bit allocating method provided by the invention has better adaptability and quantified signal to noise ratio than the adaptability and the quantified signal to noise ratio of a traditional frequency domain compression bit allocating method. The problem that a traditional frequency domain compressionalgorithm is invalid caused by the characteristics of the space-borne squint SAR that the doppler centre is nonzero and two-dimension spectral energy distribution is squint along the direction is solved.
Description
technical field [0001] The invention relates to the technical field of spaceborne squint SAR original data compression, and is a practical frequency domain compression bit allocation method for spaceborne squint SAR raw data, so as to solve the energy distribution of spaceborne squint SAR Doppler center non-zero and two-dimensional spectrum The characteristic of inclination along the azimuth leads to the failure of traditional frequency-domain compression algorithms. Background technique [0002] The main idea of spaceborne Synthetic Aperture Radar (SAR) frequency domain compression algorithm is to transform the SAR raw data into the two-dimensional frequency domain, and use the de-correlation of the frequency domain and the energy distribution characteristics of the two-dimensional spectrum to meet the transmission data rate. On the premise of improving the signal-to-noise ratio, representative compression algorithms include: FFT-BAQ (Fast Fourier Transform-Block Adaptive...
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IPC IPC(8): G01S7/02G01S13/90
Inventor 祁海明李信华斌
Owner INST OF ELECTRONICS CHINESE ACAD OF SCI