This control system is technically designed and made for 4.5M satellite antenna. Via this control system, the orientation, the pitching and polarization angle of the antenna can be easily adjusted. Adopting of the new AC servo controller greatly increased the control accuracy of every angel of the antenna. This technical application is quite advanced among its current counterparts at home.

（A）Solution of the satellite antenna control system
Adopting our servo-driven unit composed of AC servo controller and AC asynchronous electromotor, together with programmable controller and programmable terminal can build up a controlling unit.
The systematic forming scheme is as showed in the below chart:

（B）System function and technical index
    This system is composed of indoor controlling unit and outdoor servo-driven controlling unit, realizing its operation via the characters shown on the screen of the programmable terminal. The AC asynchronous electromotor of the driving antenna in the AC servo controller achieves accurate control of the location and speed to realize adjustment of the antenna’s orientation, pitching and polarization angle. The coder installation of the electromotor not only provides feedback information to the AC servo controller, but also supplys information of the antenna’s orientation and pitching to the indoor controlling unit, which used for controlling and showing the angel after process.

     Software plays an important role in realizing the various functions of the system. Its software includes the programs of AC servo controller (3 sets), programmable controller and programmable terminal, which is respectively in charge of human machine interface, data processing, motion control, status monitor and other functions. Software related with antenna is installed in the Northern Hemisphere corresponding with the location of the antenna and the system.

Operation range: orientation 90.00°(east)～270.00°(west)［exact north 180°］
Pitching angels: 5.00°(bow angel)～90.00°(elevation)
Polarization: ±90°

Operation mode:
(1) Angel operation: set up angel index and move to its location. (After fixing the first star)
(2) Stepping operation: stepping distance selection, after（little stepping distance0.01°, middle stepping distance0.05° and large stepping distance 0.25°)，single button operation: pree one time, move one step.
(3) Start/stop operation: after choosing the rotation speed of the electromotor (the speeds vary according to orientation, pitching and polarization), operated by uni-key, pressing the key for 1 time means on, next time off.

Star changing operation: find five stars` azimuth angels and pitching angles datum according to the sequence numbers. After setting the target star number, begin the star changing operation, which is very quick and easy. If the star setting doesn't land, the system will not go on performing by indicating “invalidation”.

Protection operation: make the antenna upwards if the pitching motion reaches 87.00° to protect the framework or the groundwork from the strong wind.

Location-limited protection:Location-limited switch and limited switch are set up. Location can be set to soft limitation. Confine the range of the orientation angels. Free from interference or collision.

Controlling precision:As the transducer of location and speed, built-in 2500-lines coder with the electromotor of same axis.Through the retarder, 0.01°space of the antenna's orientation axis corresponds 2333 pluses; while the pitching axis corresponds 20000 pluses. AC servo controller processes the coder’s information in 4-time(10000 pluses/round).In addition,its controlling precision is very as high as to ±1 pluse,so the integrated controlling precision is quite high.

Clearance compensation: Retarder and other machine parts produce direction-turning clearance when the electromotor changes its direction. Servo controller can compensate these clearances.

Angel display: angels with 2-bit decimals denote the datum of the satellite antenna’s location. Orientation angels use 3-bit integers and 2-bit decimals, 4舍5入 to the second bit after radix point. Pitching angles use 2 bit integers and 2 bit decimals, 4舍5入 to the second digit after radix point. Polarization angels can’t be displayed.

Alarm remanding: monitored by the AC servo controller, characters will be shown when abnormity occur. Monitored by location-limited and origin transducers , characters will be shown when abnormity occur.
Employing electrical source: controlling unit AC 220V±10%（uni-phase） 50Hz 100W servo-driven unit AC220V±10%（uni-phase） 50Hz 1000Wmax.

Overall dimension: indoor controlling unit (standard: 19 inch 3U) L:300 W:430 H:134（mm）;outdoor servo-driven unit L:250 W: 600 H: 800(mm)

Working environment temperature: indoor controlling unit 0℃～40℃; outdoor servo-driven unit －30℃～40℃(including temperature adjusting unit)

（C） Characteristics
⑴.This system adopts uni-phase AC 220V electrical source, consistent with satellite communication equipment..
⑵.Targeting its antenna orientation when the first star lands, taking pitching angels as datum to do the star leveling and star changing operation quickly and easily.
⑶.Using AC servo controller, orientation control precision is high and lasting.
⑷.Possessing many security and defending functions, such as commucative lock, location-limited, etc.
⑸.AC asynchronous motor is used in the open air where temperature and humidity change greatly. It can sustain the normal running of free maintenance.

（D）Conclusion
Adopting our company’s servo products system to adjust the medium or large diameter satellite antennas,which has many advantages, such as high controlling precision, various functions, simple operation, secure and reliable, and cost-saving.