# Performance Analysis of Ground Target Detection Utilizing Beidou Satellite Reflected Signals
## 4 Experimental Results
### Results of the Second Experiment
However, the decrease in PRN8 was not as large as that of the red dotted line of PRN8 in Figure 22c, so the change in the phase difference of PRN27 was smaller than that of PRN8. Figure 20: Results of the BeiDou PRN23 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 the second experiment, many new phenomena were found through the above analysis because of the long data acquisition period and the avoidance of human influence. Different BeiDou satellites were shown to detect 14 round-trip motions of targets, but the detection parameters and performance were different. The target detection events obtained by different parameters, such as I branch component data, phase difference information, and carrier-to-noise ratio information, are shown in Table 5. It should be pointed out that the time results for PRN2 and PRN23 were estimated based on the I branch component data from Figures 17a and 20a. In order to unify the time units, the values were rounded. Table 4.0 Results of the BeiDou PRN27 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). Table 4.1 I branch component of five BeiDou satellite reflected signals: (**a**) PRN2 satellite; (**b**) PRN3 satellite; (**c**) PRN8 satellite; (**d**) PRN23 satellite; (**e**) PRN27 satellite. It can be seen from Table 5 that the PRN8 satellite had the best target detection performance. It detected targets through I branch component data, phase difference information, and carrier-to-noise ratio information, and the trends of the three parameters were consistent with those of the PRN9 satellite in the first experiment. Comparing the time recorded when the target passed under the antenna, it was found that there was an error of about two seconds between the result of PRN8 inversion and that of PRN8 inversion. This is a normal phenomenon that occurs because data processing needs to skip the buffer data section during acquisition. The PRN3 satellite found obvious changes mainly through I branch component data and carrier-to-noise ratio information, which were basically consistent with the detection results of the PRN8 satellite, but the trends of the I branch component data and carrier-to-noise ratio were different between the two satellites. Comparing and observing the detection results of PRN2 and PRN8, when the target moved from east to west (that is, when the number of times the target passed under the antenna was odd), the detection time was basically the same. When the target moved from west to east (that is, the number of times the target passed under the antenna was even), the detection time of PRN2 satellite is about 2 s earlier than that of PRN8 satellite. The PRN27 showed the same changes, but the difference was that when the target moved from west to east, the detection time of PRN27 was about 1 s ahead of the PRN8 satellite. Comparing the detection results of the PRN23 and PRN8 satellites, when the target moved from east to west, the detection time of the PRN23 satellite was about 2 s earlier than that of the PRN8 satellite. When the target moved from west to east, the detection time was the same. In order to explain the above phenomena effectively, the positions of specular points between the five satellites and the antennas were calculated by combining the position information for satellites and antennas, and a geometric diagram was drawn, as shown in Table 4.2