Fig. 1. Diagram of FSI ranging system for non-cooperative target

Fig. 2. Data processing process

Fig. 3. Flow chart of extracting target position spectrum using SFT algorithm

Fig. 4. Flow chart of s-Rife algorithm

Fig. 5. Experimental device

Fig. 6. Comparison of spectral solutions between SFT and FFT. (a) FFT spectrum at distance to be measured; (b) SFT spectrum at distance to be measured; (c) spectrum solution deviation of two algorithms

Fig. 7. Comparison of spectrum correction effects of s-Rife, CZT, and ZFFT. (a) Spectrum corrected at target position; (b) deviation of calibration results at different distances (based on CZT algorithm)

Fig. 8. Comparison of standard deviations of measurement results when distance and incident angle of different non-cooperative targets are changed. (a) Change of distance (normal incidence); (b) change of angle (distance is 6.4 m)

Fig. 9. Comparison of ranging results. (a) Distance range is 6.4-7.2 m; (b) distance range is 11-11.8 m