# A Framework for Assessing the Interference from NGSO Satellite Systems to a Radio Astronomy System
## 4 Simulation Results
### EPFD of RAS Telescope  
In order to assess the interference of the NGSO constellation with the RAS telescope, the EPFD distribution over the field of view needs to be taken into account. In the figures below, the EPFD distribution of the RAS telescope at different latitudes is given, where the EPFD was averaged over an integration time of 2000 s and a random start time was chosen for the integration. Based on the EPFD calculation method in Section 3, the CDFs of the satellite EIRP and the beam activation probability presented, we obtained the EPFD distribution of the RAS telescope by simulation. Due to the different beam activation strategies, the RAS telescope was subject to different types of interference. The simulation results for the three activation probabilities are shown in Figures 9-11, respectively. These diagrams show the EPFD results of an RAS telescope in the northern hemisphere. The angle in the radial direction represents the residual angle of the elevation angle of the telescope, while the angle in the circumferential direction represents its azimuth. The angles were used to determine the orientation of the telescope relative to the horizon.  
According to Figure 9, the density of red highlights in the plot increases from left to right. This indicates that as the latitude of the RAS telescope increased, the telescope experienced greater interference. This is likely due to the fact that in a constellation of polar-orbiting satellites, the higher the latitude, the greater the number of visible satellites and thus the stronger the interference with the RAS station.  
According to Figure 10, the simulation results were similar to those of Figure 9. The higher the latitude of the RAS telescope, the stronger the interference was. Since the beam activation probability for method 2 was smaller than that of method 1. The simulation results were therefore slightly smaller than those in Figure 9, which was more obvious in the first two subfigures.  
According to the simulation results in Figure 11, the interference to the RAS telescope was minimal. The interference to the RAS telescope in the first three subplots was insignificant. This is likely because the beam activation probability of method 3 was closely matched to the world population density distribution, which is lower at many latitudes, thus reducing the interference to the RAS station.  
Figure 9: The EPFD of an RAS telescope with the beam activation of method 1: (**a**) the latitude of the RAS telescope is 0 degrees; (**b**) the latitude of the RAS telescope is 30 degrees; (**c**) the latitude of the RAS telescope is 60 degrees; (**d**) the latitude of the RAS telescope is 90 degrees.  
Based on the simulation results of the RAS telescope, it was clear that both the number of satellites and the probability of beam activation had a significant impact on the interference experienced by the RAS telescope. The concentration of satellites in polar orbits led to significant interference to RAS telescopes at higher latitudes. To mitigate this interference, the NGSO constellation beam scheduling strategy should be designed to reduce the probability of beam activation while still meeting user requirements. Careful planning and consideration of system parameters are essential for the successful coexistence of LEO satellite constellations and RASs.