SES World Skies Avoids Stray Satellite Interference
SES World Skies successfully avoided signal interference from Intelsat’s stray Galaxy 15 satellite that drifted into SES’s orbital space, both companies said. While the satellite remains within SES’s orbital slot at 131 degrees west, it’s out of range to pose an interference threat to AMC-11, SES World Skies’ satellite in that slot. Galaxy’s expected to exit the AMC-11 orbital space June 7, said Intelsat. Intelsat lost communication with Galaxy in April (CD April 9 p10) and has been unable to keep the satellite from drifting even though its transponders remain active. The companies were concerned the proximity of the two satellites’ active C-band transponders could interrupt service for customers on the AMC-11 satellite.
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While Galaxy 15 is continuing to move through orbital slots, the next satellites it will come close to are operated by Intelsat, making interference avoidance and coordination easier for the company, an Intelsat spokeswoman said. Intelsat will likely begin a second wave of high power signal blasts hoped to regain control of the satellite, she said. A similar signal blast attempt before Galaxy 15 entered the 131 degrees west slot was unsuccessful. Intelsat must wait for the satellite to exit the orbital space before trying the signal blast since they could also cause interference to nearby satellites.
SES used a complicated maneuver to minimize chances of interference Saturday and Sunday. The company switched AMC-11 customers to its recently launched SES-1 satellite while AMC-11 drifted eastward parallel to Galaxy 15. The maneuver allowed the company to move customers over the interference source. AMC-11 is largely used for cable feeds. “We have leapfrogged [Galaxy 15] successfully and are moving back into our designated slot,” said an SES spokesman. “The whole scheme worked as planned, without complaints."
Intelsat helped SES by providing a 19-meter uplink tracking antenna for use by AMC-11 customers. The “high signal directivity provided by the antenna produced a ‘pencil beam’, focusing more carrier energy directly to AMC-11 and reducing that same carrier energy away from Galaxy 15, avoiding any perceptible signal interference,” Intelsat said.