# Performance Analysis of Ground Target Detection Utilizing Beidou Satellite Reflected Signals
## 4 Experimental Results
### Results of the Second Experiment
Figure 17: Results for the BeiDou PRN2 satellite reflected signal: (**a**) I branch component data; (**b**) Q branch component data; (**c**) phase difference information (in ms); (**d**) phase difference information (in s). In Figure 20, the overall change of PRN23 satellite was similar to that of PRN3 satellite. A slight difference is that there were 14 increased data segments in the I branch component data, but the amplitude was not large, around 3000, while the increase in the I branch component data of the PRN3 satellite was maintained at 4000. Compared with the carrier-to-noise ratio information of the two satellites, the signal intensity of the PRN23 satellite was also significantly less than that of the PRN3 satellite. At the same time, the carrier-to-noise ratio of the PRN23 satellite fluctuated upwards and downwards with the movement of the target, and there was no indication that the CNR information of the PRN3 satellite increased regularly, as shown in Figure 16c. Figure 19: Results of the BeiDou PRN8 satellite reflected signal: (**a**) I branch component data; (**b**) Q branch component data; (**c**) phase difference information (in ms); (**d**) phase difference information (in s). Figure 18: Results for the BeiDou PRN3 satellite reflected signal: (**a**) I branch component data; (**b**) Q branch component data; (**c**) phase difference information (in ms); (**d**) phase difference information (in s). As shown in Figure 21, the changes in the I branch component data and phase difference information of the PRN27 satellite were quite different from those of the other satellites. As shown in Figure 21a, the I branch component changed 14 times. Unlike several other satellites, the amplitude of the I branch component data increased and decreased simultaneously when the target passed under the antenna. Combined with the CNR information shown in Figure 16d, the same phenomenon appeared in the PRN27 satellite reflection signal intensity. In addition, the change in the phase difference of the target was also reflected (as shown in Figure 16d), but the change range was small, within \(-50^{\circ}\) to \(50^{\circ}\), while that of the PRN8 satellite was near \(90^{\circ}\). In order to explain the special phenomenon of five satellite reflected signals more clearly, a period of data was intercepted from the I branch component of the five satellites; the time length was 6000-28,000 ms. This time period included the first time the target moved (from west to east) and the second time it moved (from east to west) under the antenna, as shown in Figure 22.  
Green box 1 in Figure 22e clearly shows that when the target passed under the antenna for the first time (from west to east), the I branch component of the PRN27 satellite underwent a process of oscillation, descent, and ascent, and recovered to its normal level after the target passed through. Green box 2 shows the change in the I branch component when the target passed under the antenna for the second time (from east to west), which was contrary to the trend of box 1. Comparing the I branch component data in the green box in Figure 22a, we also observed the same change, but the change range was small. It should be mentioned that the green box in Figure 22d indicates the change trend of the PRN23 satellite I branch data during the second time that the target passed under the antenna (from west to east), similar to that of PRN27 satellite green box 2 in Figure 22e. However, there were two differences: (1) the moving direction of the target was different when it passed through the antenna, and (2) the range of variation for the I branch component data of the PRN23 satellite was smaller than that of the latter. The red dotted line in Figure 22e is the time period during which the I branch component declined. It is the reason why the phase difference of the PRN27 satellite (shown in Figure 21d) changed significantly.