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基于冲激响应原理的步进频率探地雷达信号快速正演模拟及融合
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Abstract:
步进频率调制连续波(Stepped-frequency Continuous Wave, SFCW)体制探地雷达作为频域探地雷达的一种，与冲激脉冲体制探地雷达相比，具有可控的发射信号频率，更高的平均发射功率，更大的探测深度及更高的分辨率。目前步进频率探地雷达采用多种不同频率的发射信号，在数值模拟方面运算量成倍增加，信号融合方法尚不成熟。本文针对步进频率探地雷达进行正演模拟研究，采用开源程序gprMax，结合线性时不变系统(LTI)的冲激响应，提升正演效率，避免重复进行正演计算。将正演得到的反射信号与发射信号进行混频，对结果进行低通滤波提取与目标体距离有关的相位信息，然后通过逆傅里叶变换到时域内进行信号融合。通过在正演模拟中加入噪声对比研究了冲体制雷达和步进频率体制雷达的抗噪性能，结果表明SFCW探地雷达在噪声条件下对目标检测结果具有更高的信噪比。
Stepped-frequency continuous wave ground penetrating radar (SFCW GPR) is a kind of frequen-cy-domain GPR. It has controllable signal frequency, bigger average transmitting power, deeper penetration and higher resolution compared to pulsed GPR. At present, stepped frequency ground penetrating radar contains different frequencies of transmit signal, so the amount of calculation in the numerical simulation has doubled, and the signal fusion method is not yet mature. This paper conducts forward simulation research of SFCW GPR, the open source program gprMax has been used combined with the impulse response of linear time-invariant system to improve simulation efficiency and avoid repeated forward calculation. The reflected signal obtained by simulation is mixed with transmitted signal and goes through low-pass filter to extract the phase information related to the distance of target, then the result is converted to time domain through inverse Fourier transform for signal fusion. We have compared the anti-noise performance of pulsed GPR and SFCW GPR by adding noise to the simulation. The results show that SFCW GPR has a higher signal-to-noise ratio for target detection under noisy condition.
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