Doug Lung /
12.29.2011 12:00 AM
Satellites—Galaxy 15 Returns to Service

One of the big satellite news stories of 2010 was the drift of Galaxy 15 across the satellite arc with transponders on after Intelsat lost control of it. At the end of 2010, Galaxy 15 rebooted and Intelsat regained control. In October 2011 the satellite returned to service at its original location at 133 degrees west longitude. The engineering team at Intelsat and Orbital Sciences Corp. did a great job mitigating interference from Galaxy 15 as it drifted past other satellites and in bringing this "Zombie satellite" (as it was called in the press) back to a normal life.

Last year I wrote "Ka-band satellite operators have focused on using their spectrum for HDTV content distribution rather than broadband." 2011 saw the successful launch and testing of ViaSat-1, a Ka-band satellite with 1.5 GHz each of uplink and downlink spectrum and multiple spot beams allowing frequency reuse. Eutelsat's KA-SAT Ka-band satellite became operational in 2011 and is being used for uploading video files from remote locations as I recently reported. It appears from recent FCC applications there will be another Ka-band satellite at 97 degrees with the same capacity as ViaSat-1, for customers in the Americas.

LightSquared managed to consolidate its bits of L-band spectrum at 1.5 and 1.6 GHz by working with Inmarsat and was poised to launch a hybrid satellite/terrestrial LTE-based broadband network until tests revealed existing GPS receivers were unable to reject the strong signals from LightSquared terrestrial base stations operating close to the GPS band. LightSquared made several attempts to reduce the interference problem by lowering power and not using its spectrum closest to the GPS band, but recent testing still showed interference to a large number of GPS receivers, as I reported in RF Report. The problem is that, while GPS receivers would not have had a problem with the signals from satellites in the bands near GPS, manufacturers did not, and some say could not, design the receivers to handle the far stronger signals on these frequencies from terrestrial base stations.

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