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星载合成孔径雷达(SAR)压缩后的原始数据信噪比是SAR系统设计时原始数据压缩比选取以及应用分析的重要理论依据,前人常用的量化信噪比并不能完全表征压缩后信号与噪声的关系.本文提出了量化区间跃迁的统计概率模型,旨在得出考虑系统噪声情况下,饱和度全集上星载SAR原始数据信噪比在ADC前与BAQ后的映射关系:当回波信号功率较小,输入信噪比较低时,4bit,3bit,2bit,1bitBAQ压缩后信噪比区别不大;当回波为中等功率信号且信噪比较高时,压缩比特数每减少1bit,信噪比恶化约5dB;当回波功率较大,ADC饱和时,量化后原始数据信噪比呈阶跃性下降,饱和度越高,信噪比恶化越严重.本文采用模拟高斯数据和实测SAR原始数据验证了理论结果的正确性,为星载SAR系统设计时BAQ压缩比的选取以及后续的应用分析提供了理论依据.
The SNR of raw data compressed by spaceborne synthetic aperture radar (SAR) is an important theoretical basis for selection and application analysis of original data compression ratio in SAR system design. The quantization SNR commonly used in the past can not fully characterize the signal after compression Noise.This paper proposes a statistical probability model for quantizing interval transitions to obtain the mapping relationship between the signal to noise ratio of the original spaceborne SAR data and the BAQ after considering the system noise under the complete set of saturations: Signal power is small, the input signal to noise ratio is low, 4bit, 3bit, 2bit, 1bitBAQ compressed signal to noise ratio is not much difference; when the echo is medium power signal and the signal to noise ratio is high, the number of bits to reduce compression 1bit , The signal-to-noise ratio deteriorates by about 5dB.When the echo power is large and the ADC is saturated, the signal-to-noise ratio of the original data after quantization decreases stepwise, and the higher the saturation is, the worse the signal-noise ratio deteriorates.This paper uses simulated Gaussian data and The measured SAR raw data verify the correctness of the theoretical results and provide a theoretical basis for the selection of the BAQ compression ratio in the design of spaceborne SAR systems and the subsequent application analysis.