Center of Box Definition
Center of box predictions are used to orient earth station antennae. It is normal for satellites to move within their box due to gravitational and other effects associated with the Earth, sun, and moon. It is important that ground station antennas are aligned when the satellite is passing through box center for peak performance.
In space, satellites are not motionless; they have daily movements because they spin following the Earth's rotation. With center of box predictions, the antenna(e) direction can be corrected. It is recommended that master antenna isolation and direction adjustments be carried out when the satellite is closest to the center of box.
Geosynchronous satellites are assigned specific longitudinal positions above the equator. To reduce adjacent satellite interference, satellite stations or "boxes" are defined at these positions in the east-west and north-south directions. A satellite's box size is assigned based upon its operational frequency band and is defined as follows:
C-band:Assigned longitude ±0.05o and 0o Latitude ±0.05o (box size of 0.10o in the E-W/N-S directions); approximately 45 miles on a side. Ku-band: Assigned longitude ±0.05o and 0o Latitude ±0.05o (box size of 0.10o in the E-W/N-S directions); approximately 45 miles on a side.
Satellite Box Center is a smaller box defined as the assigned longitude ±0.005o and 0o Latitude ±0.005o. This is essentially a smaller box approximately 4.5 miles on a side. It is normal for satellites to move within their box due to gravitational and other effects associated with the Earth, sun, and moon. It is important that ground station antennas are aligned when the satellite is passing through box center for peak performance.
Should you require technical assistance, please send an e-mail directly to satops.americom@ses-americom.com or call the appropriate operations center:
For AMC-1, AMC-7, AMC-8, AMC-9, AMC-10, AMC-11, AMC-18, *AMC-23 and Satcom C3 please call +1-800-255-6122 in the U.S. or +1-973-823-6000 from all other locations.
For AMC-2, AMC-3, AMC-4, AMC-5, AMC-6, AMC-15 and AMC-16 please call +1-800-772-2363 in the U.S. or +1-410-549-4300 from all other locations.
All times referenced below are GMT.
back
* SES has agreed to a split-off transaction with GE in which SES contributes its participations in AsiaSat, Star One, SATLYNX, and Orbcomm, the AMC-23 satellite and its related business, as well as cash into a new company, SES International Holdings (SIH). SIH will be exchanged for GE’s entire shareholding in SES, subject to satisfaction of closing conditions.