The System Design And Signal Processing Of SF-GPR

Step Frequency-Ground Penetrating Radar (SF-GPR) is a very successful nondestructive detection technology for underground objects. In this paper, system design and signal processing of SF-GPR are studied. Firstly, a signal model of received radar data in a lossy medium is developed. The model of received radar data is obtained based on the radar geometry and polynomial expansion approximations of the wavenumber in a lossy medium. Then, the basic operation principles and radar system design of SF-GPR are discussed. The system design of SF-GPR includes architecture design and radar parameter selection. The architecture design includes the design of radar transceiver, step frequency synthesizer and signal processing. Heterodyne system is used for SF-GPR to achieve high sensitivity. The procedure of receiving and sampling of the radar signals is analyzed based on the system architecture. The key radar parameters and their impacts on radar performance are analyzed. The limitation of radar performance by lossy medium and system noise is analyzed. Lastly, the general signal processing technique for SF-GPR and the signal processing techniques for some special situations are presented. The conventional procedure of signal processing—FFT, and the influences of the frequency domain sample number to the target images are analyzed. The feasibility of a super resolution technique—MUSIC(MUltiple SIgnal Classification) for signal processing of SF-GPR is analyzed and verified, the performance of MUSIC is compared with FFT. The possible problem of target imaging and boundary depth estimation of multi-layer medium is discussed. The influence of the frequency dispersion of antennas to the target images is analyzed.