To record the data transmitted by the satellite, the receiving antenna must follow and continually point directly at the satellite. How is this done?

2.5.1. Ephemeris data (tables of the predicted location of the satellite) are used to aim the antenna at the expected location (azimuth and elevation) of the satellite as it appears over the horizon.

2.5.2. A computer moves the antenna, following along the predicted orbit of the satellite and searches for its X-band transmission. If a transmission is detected and if the signal is strong enough, the computer will track the satellite, using the X-band signal, rather than the ephemeris data.