This is with reference to Arcedeon’s question in the ‘comments ‘ section. The answer became too big for a comment- we made it a blog post instead. So here it is.
The estimated location of satellite is obtained from TLE data.This is in turn used as a reference for the rotor so that it knows when to point at what direction & at the point.
The control system used for tracking is as follows:
TLE data is updated from the organization’s (www.spacetrack.org) website.TLE file package is downloaded from the website as & when needed.
If we are using an auto software based system, the software may have the capability to download this auto & update itself or we may have to do the same.
If we are using a home brewed set up, the TLE data coordinates are burnt as a hex file in the Microcontroller (MuC)
Once the TLE data has been received in the software or MuC, it is sent to antenna rotor system using a rotor interface circuit.
The use of this circuit is to decide
1) Degree of rotation of antenna
2) Value of torque to be provided by the motor (current , voltage regulation)
3) When to switch on & switch off the motors
Since the antenna are mounted on the motor, when the entire control system kicks into action, taking TLE data as reference, the antennas mounted on the rotor are automatically aligned in the exact direction of sat so that at all given times antenna tracks the satellite accurately.
