When using rotatable satellite antennas, the first task is to locate the satellite and then to position the parabolic antenna precisely. Systems that support the technique of automatic satellite localization are called Universal Satellites Automatic Location System (USALS).
USALS systems can automatically locate satellites, provided that the exact longitude and latitude of the location of the satellite antenna are known. Once these coordinates are known, the USALS system can calculate the satellite position in orbit and position the parabolic antenna with an accuracy of 0.1 degrees. The positioning data is stored and used for motor control. USALS thus meets the specifications described in Digital Satellite Equipment Control( DiSEqC 1.2 and 1.3).
Satellite antennas can be controlled by the receivers that have licensed USALS, implemented the satellite positions and update this position database when the satellite position changes or when new TV satellites are added. If the user switches his receiver from one satellite to another, then the stored positions are driven by a motor control.