## 3 Data Analyses
### Experiments and Analyses
After the radar began to measure the target, the distance error converged rapidly, and the average compound spatial distance error was approximately 160 m. During the \"S\"-shaped maneuvers, the carrier aircraft produced more obvious fluctuations of the compound spatial distance error of approximately 50 m. With the proximity of the distance between the carrier and target, the distance error  
Figure 12: Speed information issued by the carrier to the pod. Figure 13: The pod’s power supply voltage. decreased gradually, and the line-of-sight angle between the carrier and target increased gradually until the airborne radar lost the target after producing a large distance error. Based on the evaluation model introduced in Section 3.2, the compound spatial distance error was generated by the north, west, and sky distance error components. Considering the first simulated autonomous flight as an example, the three directional distance error components are shown in Figure 16.  
Figure 14: Time sequence of the pod’s power supply. Figure 9:0 Spatial compound distance error of the target position measured by the airborne radar. Furthermore, the pitch and heading angle measurement errors incurred by the airborne radar measuring and tracking the target aircraft were obtained from Equations (3) and (4), as shown in Figures 17 and 18. It can be concluded that in the stage of stable tracking of the target (excluding the target loss due to the large line-of-sight angle before the two-machine rendezvous), the average pitch and heading angle errors were 0.26\({}^{\circ}\) and 0.24\({}^{\circ}\), respectively, and the change was considered limited when the distance varied. Figure 9:1 Distance error and its three directional components of the first simulated flight. Figure 9:2 Pitch angle error of the target measured by the airborne radar. After receiving the target information from the carrier containing the measurement error of the airborne radar, based on the transformation and calculation, the guidance angle was generated to guide the seeker via tracking and interception of the target. The errors considered in the guidance angle included measurement errors of the airborne radar, errors in the navigation calculation of the pod (including hanging errors with the carrier such as mounting error, and transmission errors such as wing deformation), as well as errors due to the radar guidance system in the pod. To evaluate the self-error of the guidance system, the difference between the guidance angle (recorded by the data recording device in the pod) and the intercepted target angle returned by the pod radar guidance system (recorded by the data recording device in the pod) was acquired. Considering the first simulated autonomous flight as an example, the accumulated errors of the radar guidance system intercepting the target are shown in Figure 9:3  
Figure 9:4 Accumulated errors of target interception by the radar guidance system. Figure 9:5 Heading angle error of the target measured by the airborne radar. Based on the difference between the accumulated errors of the target interception by the radar guidance system and target measurement errors due to the airborne radar, the error incurred by the radar guidance system was then evaluated. Subsequently, accuracy analyses of the radar guidance system under simulated flight conditions were completed. By considering the first simulated autonomous flight as an example, the intrinsic errors of the radar guidance system are shown in Figure 9:6  
The abovementioned radar guidance system errors will adversely affect guidance accuracy. A variety of factors can cause errors, such as antenna pre-set error, electric axis null position error, antenna front installation error, thermal noise, and line of sight error of the radome. Different design schemes and production levels of radar guidance systems also lead to different levels of error influence. Antenna pre-set errors are mainly influenced by variables such as position feedback accuracy, pre-set voltage accuracy, and maximum pre-set angle.