UAVs Strain Sat Bandwidth

You've probably seen reports on the military's use of unmanned aerial vehicles (UAVs), and even pictures from the aircraft on the news, but have you considered the amount of bandwidth it takes to get the video and sensor data from these aircraft back to the pilots remotely flying them from U.S. locations?

A story published last week, French Air Chief: UAV's Taxing Available Satellite Bandwidth, outlined the challenges in relaying an ever increasing amount of data from UAVs.

In addition to high-definition video, the UAVs sensors include imaging radar, ground moving target indicators and multispectral imagers. Approximately 20 Gbps of data is needed to cope with the growing number of UAVs, swamping current Ku-band satellite links. One of the alternatives is Ka-band.

"Ka band appears to me as an interesting option," said French Air Chief of Staff General Jean-Paul Palomeros. "Even if the signals are much more sensitive to weather conditions."

The article stated that "adaptive codage modulation" could be used to help limit the impact of weather on the signal, but the real solution is a dual Ka-Ku-band antenna that could drop back to Ku-band frequencies in areas where weather was a problem. Palomeros lists several other options in the Defense News article.

In an unrelated press release, ViaSat announced it publicly demonstrated 8 Mbps airborne broadband satcom performance via a 12-inch Ka-band satellite antenna for the U.S. armed services, including representatives from the Air Force, Army, Marines, and Special Forces. The network used the ViaSat VR-12 Ka airborne satellite antenna and ArcLight 2 modem mounted to a mobile vehicle that drove around the Carlsbad, NM area. ViaSat didn't indicate what satellite it used for the test. ViaSat's ViaSat-1, which has 1.5 GHz uplink and the same amount of downlink Ka-band spectrum reached geosynchronous orbit only two weeks ago and probably wasn't ready for the demonstration.

"Achieving this level of satellite system performance in such a small physical package is another important milestone for us and especially for our broadband ISR customers," said Larry Taylor, deputy GM, ViaSat Global Mobile Broadband. "We didn't anticipate conducting the exercise during a rainstorm, but though that worst case happened, the network performed all day without a single link loss."

Perhaps the wait for low-cost, compact, and automatically-aiming Ka-band SNG links is almost over.

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.