## 3 Multipath Interference Suppression
The normalized minimum mean square error of the height estimation achieved by the LCT+MF method reaches \(10^{-3}\) when SNR = \(-17\) dB and the estimation performance of the MF+LCT method reaches \(10^{-3}\) when SNR = \(-21\) dB. From the above, the proposed methods have good estimation performance, which shows that the aerial target parameter estimation methods have good interference suppression effect. From Figure 16, both the proposed LCT+MF method and the proposed MF+LCT method in this paper can achieve the good estimation performance of the target flight speed, and estimation performance improves as SNR increases. When SNR = \(-19\) dB, the LCT+MF method and MF+LCT method can reach \(10^{-3}\), and the MF+LCT method is better than LCT+MF in the case of low SNR. These results show that the LCT algorithm has a good suppression effect on interference. To compare the parameter estimation performance of the proposed method with [34], the parameters are set as follows: the sampling frequency is \(f_{s}=10.23\) MHz, the sampling points is \(3\times 10^{7}\), the GPS direct wave power is \(P_{d}=-100\) dBm, the symbol rate is \(f_{Gb}=1.023\) MHz, the carrier frequency is \(f_{c}=1.57\) GHz, the target flight altitude is \(8\) km, the flight speed is \(125\) m/s, the average power of the echo signal is \(P_{r}=-135\) dBm; \(2000\) Monte Carlo simulation results are used. Figure 14: Sensing performance with different methods. It can be seen from Figures 17 and 18 that the proposed method is better than [34]. This is because the proposed method completes the estimation of the target motion parameters based on the LCT based on the analysis of the forward scattered signal. The MF+LCT method and LCT+MF adopt the noise suppression effect of LCT and the time delay characteristics of the forward scattered signal, thus the proposed method has better estimation performance at low SNR. The computational complexity of the two methods are \(O(MN\cdot n_{lct}+N\cdot n)\) and \(O(MN\cdot n)\), respectively, and the computational complexity of [34] is \(O(N\cdot n)\), where \(n\) is the total number of searches for speed and altitude. From the

Figure 16: Speed estimation performance with different SNRs. Figure 15: Height estimation performance with different SNRs. above, although the computational complexity of the proposed methods is higher than [34], the proposed method can achieve better target parameter estimation performance. ## 9 Conclusions

This paper has proposed a novel aerial target passive sensing method based on linear canonical transformation, in which the proposed method adopts the forward scatter radar model and satellite communication waveforms characteristics. Linear canonical transformation is used to achieve the multipath interference suppression in the receiving channel and design target detector. In addition, the characteristics of linear canonical and the matching filtering are used to achieve accurate target parameters estimate. Numerical results have demonstrated that the proposed method can perform effective target sensing and target parameter estimation by satellite based forward scatter radar. Satellite-based

Figure 17: Height estimation performance with different methods. Figure 18: Speed estimation performance with different methods. target detection technology has become an important research direction in the field of passive detection. This paper has carried out a certain exploration in this field, but there are still other areas that can be further studied. In this paper, the research on GPS satellite target detection is based on theoretical modeling and computer simulation environment, and the actual environment and system model are simplified to some extent in the experiment.