I want to determine the time interval during which a ground user is in the coverage of a particular LEO satellite. I only have knowledge of the user's geographical location and the satellite's TLE (orbital) information.
As per my knowledge, we can extract the satellite's geographic location at any timestamp from the TLE information, thereby calculating the elevation angle between the satellite and the user. From some sources, I got to know that the user can be assumed to be in the coverage of the satellite if the elevation angle is above 10 degrees. However, in this manner, I will need to continue to calculate the elevation angle for future timestamps until the elevation angle goes below 10 degrees to determine the coverage time which is not very efficient.
Is there any other better way to calculate the coverage/service time for a user with respect to a LEO satellite given the above information? Thanks in advance.