THE MIL & AERO BLOG, 30 July 2013. Satellite communications (SATCOM) is a crucial link in the ability of the U.S. military and its allies to move important voice, text, imagery, video, and other important data over long distances. In fact, the broad adoption of SATCOM over the past few decades has forced other modes of long-haul communications into the back seat.
Still, the relatively high and recurring costs of SATCOM, as well as its potential vulnerability to jamming and hacking may be encouraging military planners to take a second look at long-haul communications alternatives to SATCOM, such as high-frequency (HF) radio and tropospheric scatter (troposcatter) communications.
The costs of SATCOM are well known. It's expensive to design and launch satellites, as well as to maintain them in orbit. The military also can lease bandwidth on commercial satellites, but this approach involves recurring costs. In this era of sequestration and tight budgets, Pentagon officials are looking to cut costs wherever they can without compromising national security.
The vulnerabilities of SATCOM also represent a growing concern, as they relate to the new military discipline of spectrum warfare -- an umbrella term that describes the convergence of electronic warfare (EW) and cyber warfare.
The vulnerabilities of SATCOM to electronic jamming is starting to be understood. It's difficult, in that SATCOM signals tend to be directional, but still is possible. The vulnerabilities of SATCOM to cyber warfare attacks is just starting to be considered.
Then there's the obvious vulnerability of all orbiting satellites to the threat of nuclear explosion in space. The resulting electro-magnetic pulse (EMP) from an atomic blast in space has the potential to destroy or disrupt all but the most hardened military satellites.
So, what to do?
There are indications that military leaders are giving troposcatter communications, HF radio, and other terrestrial forms of long-haul communications another look. Communications experts point out that HF radio has been making remarkable advances over the last decade or so.
This technology now has the ability to send and receive data at 9,600 bits per second reliably. Earlier this year an experiment transmitted streaming color video. Ground wave HF, moreover, is being used for differential GPS positioning systems on offshore oil drilling rigs and survey vessels.
U.S. Army researchers also are considering troposcatter communications for fixed-site and on-the-move long-range military communications as an alternative to SATCOM. Troposcatter transmits and receives microwave signals at beyond-line-of-sight distances as far as 200 miles by bouncing radio signals off layers of the Earth's atmosphere.
As more attention and research goes into communications technologies like HF and troposcatter, a growing number of alternatives to SATCOM likely will emerge to get the message through economically and reliably.