For a soldier or Marine, satcom is a beautiful thing.
Satellite communications can deliver critical kilobit-heavy data, like the video feed from an unmanned aerial vehicle, to dismounted troops without the transmission being interrupted by a hill or some other obstruction that would normally thwart UHF radio or cellular communications.
The issue with satellite communications, however, has been the size of the ground stations that the troops have had to transport to the field. Still, very small aperture terminals (VSATs) have been shedding pounds thanks to lighter materials, advanced waveforms and high-throughput satellites. VSATs are now migrating to manned and unmanned aircraft.
FROM HEADQUARTERS TO TACTICAL UAV
During the 1991 Gulf War, satellite communications centered around one big fixed antenna, 2 to 3 meters in diameter, and was located back at headquarters. Everyone else would be connected by regular two-way radio, said Rick Lober, vice president and general manager of the Defense and Intelligence Systems Division at Hughes Network Systems.
However, by 2003, dish sizes got down to 1 meter, with smaller units carrying terminals into the field with them.
“We’re now down to 18 inches, even 12 inches,” Lober said,
adding that his company his working on reducing the size even further.
Clearly, VSATs are benefiting from increasingly advanced waveforms, said Fred Rieck, manager of strategy and product development at TeleCommunication Systems (TCS). In addition, the terminals are getting lighter as new polymers and carbon fibers replace metal in the reflector, body and pedestal, and motors and gears continue to shrink.
Rieck cites the evolution of his company’s SIPR/NIPR Access Point (SNAP) VSAT as an example of this trend. The first SNAP system, of which 800 units are at the Army battalion and brigade level, weighs 1,200 pounds. By contrast, the new SNAP Lite, being deployed this year at the company level, has a smaller footprint and weighs only 450 pounds.
VSATs are also moving onto aircraft. It’s still a small market for satellite terminals and there are some challenges — the VSAT must not interfere with other electronics on the platform; the antenna and modem must be tightly coupled and have a shared communications protocol so satellite connections are not lost in transit — but it’s growing, said Karl Fuchs, vice president of technology at iDirect Government Technologies.
How small can these airborne VSATs get?
“I think that there is a possibility we get down small enough that we could do some level of Ka-band connectivity on a Shadow-sized UAV,” Lober suggests.
SATELLITES: THE OTHER HALF OF THE STORY
Changes on the terminal side are certainly welcome, said Michael Geist, director of government programs for ViaSat. However, satellite capabilities must likewise be addressed.
“By just shrinking the size of the terminal and not taking into account the satellite network you are operating only answers half the question,” Geist said.
In October 2011, the company launched ViaSat-1, a commercial spot-beam satellite that set a record for capacity. Whereas the DoD’s Wideband Global Satcom system — which added a sixth satellite in early August — can deliver 2 to 3 gigabits per second, ViaSat-1 has a throughput of 140 gigabits per second.
(Of course, all this comes with added complexity, said Fuchs. To seamlessly move from spot beam to spot beam, airborne terminals require two separate demodulators and sophisticated programming.)
Geist said ViaSat is looking to adapt its satellites — ViaSat-2 is set to launch in 2016 — to DoD requirements, which he promises will significantly benefit the military user.
“Because the satellite has better reception capabilities, you can get away with a smaller transmitter on the terminal,” he said. “You can get into very low-cost remote terminal hardware.”
This low-cost equipment will then help proliferate satellite comms throughout the Army.
“There has been a desire to take beyond-line-of-sight communications down to the company level,” Geist said, “but there has always been a challenge associated with that: whether it is affordable.” He said the new SNAP Lite system is a pricey bandwidth solution because it employs very robust modulation and coding points to work with legacy satellites.
Looking further into the future, Rieck at TCS sees a multitude of tiny orbiting cubesats that will eliminate the need for directional antennas on ground terminals. Sure, the current data rate for these platforms is low, which precludes streaming video imagery, he said, “But so were the original modems, at 9.6 kilobits per second, and now they do that same connection wirelessly at 108 megabits per second.”