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Improvising Around A Disaster
The first of the U.S. Air Force’s AEHF (Advanced Extremely High Frequency) communications satellite was launched on August 14th. It achieved its initial orbit, but then it was discovered that its main maneuvering rocket, needed to get the six ton satellite into its permanent fixed, 36,000 kilometer, orbit, was not working. Efforts to get the main engine going failed. The engineers then went to work and found a way to use the lower thrust maneuvering rockets to still the AEHF bird into position. But the alternate method will be slower, and take about nine months. That’s a small price to pay for a satellite that is supposed to last 14 years, once you get it in the right position. AEHFs will replace the older MILSTAR birds, providing more abundant and reliable (jam-resistant) communications. Two more AEHFs are under construction, with one going up next year and another in 2012. Several more will be ordered if the first three (costing about $2.2 billion each) perform as expected. The cost of the first three includes development costs, so additional ones will cost less than half as much.
While the AEHF are mainly to facilitate communications between headquarters in the United States and troops abroad, they are also up there to deal with the huge increase in wireless devices the troops are using. For example, the number of military radios has nearly tripled, to over 900,000, in the last decade. There has also been a huge increase in data transmission capability (“bandwidth”) from 46 megabits (million bits) per second in late 2001, to nearly ten giga (billion) bits per second now. This is just for troops in CENTCOM (the Middle East and Afghanistan). That’s 200 times more data being pushed through three times as many “wireless devices” (radios). This doesn’t even count the many cell phones and laptops used by troops in the combat zone, which often use civilian bandwidth. But it hasn’t been enough.
The major consumer of all this new bandwidth is live video being generated by the increasing number of vidcams on the battlefield. These vids are being exchanged by the units cooperating in an operation. This huge growth in bandwidth began in the 1990s, when the U.S. armed forces moved to satellite communications in a big way. This made sense, especially where troops often have to set up shop in out of the way places and need a reliable way to keep in touch with nearby forces on land and sea, as well as bases and headquarters back in the United States. At the time of the 1991 Gulf War, there was enough satellite bandwidth in the Persian Gulf for about 1,300 simultaneous phone calls. Or, 12 megabits per second. But while the military has a lot more satellite capacity now (the exact amount is a secret), demand has increased even faster. UAV reconnaissance aircraft use enormous amounts of satellite capacity. The Global Hawk needed 500 megabits per second, and Predators about half as much. The major consumer of bandwidth is the live video.
UAVs have other sensors as well, as do aircraft. A voice radio connection only takes about 240 bytes per second, and each of the multiple channels needed to control the UAVs use about the same. But it adds up, especially since the military wants high resolution video. At the moment, the U.S. has far more demand for satellite communications than it can support. As a result, not all the Predator and Global Hawk UAVs in combat zones have sufficient bandwidth to send their video back to the United States. Data compression and using lower resolution is often necessary, or using satellite substitutes (aircraft carrying transponders) to send the video to local users. The substitutes are becoming more common, simply because there is neither the money, nor the time, to get sufficient satellites into orbit.
While the larger UAVs need satcomm to send video back to the United States, most of the bandwidth demand now is for local use. Tanks, helicopters and aircraft are all sending and receiving more vids, maps and data of all sorts. AEHF is needed to get essential material to higher headquarters as quickly as possible. The basic idea is to keep everyone connected, all the time. More radios, and other wireless devices are on the way, as well as more features any Internet user would recognize, all available while under fire. AEHF is an essential link in this data chain.
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ViaSat gives war effort a boost
Airplanes passing silently over enemy territory in Iraq and Afghanistan record and transmit videos in real time back to intelligence experts in the United States with the help of Carlsbad satellite communications company ViaSat.
Because those videos help inform military decisions, picture quality is extremely important, said Larry Taylor, the head of Government Satellite Communications Systems at the company.
To boost the resolution and speed of these videos, ViaSat recently doubled the data rate its equipment can transmit, from 512 to 1024 kilobytes. This upgrade was made at the request of the Department of Defense, one of the company’s biggest customers, Taylor said.
The company also recently improved military planes’ ability to send data back to the ground.
“Traditionally when we think of Internet access, we think about a simple mouse-click to load a complex Web page, which is a lot of data going out to a remote facility, but very little coming back,” Taylor said. “But with the Department of Defense, they are actually creating the data as videos or other intelligence information collected on an airplane, and that information has to be relayed to analysis centers on the ground.”
Giving an airplane a wireless connection is like hitting a moving target, because the plane’s antennas are never in the same place. ViaSat accomplishes this task with a network of 13 hubs on the ground connected to 13 satellites, which create a “worldwide footprint” of wireless connection, Taylor said.
Boosting the planes’ data speed will allow them to send videos with higher resolution and more frames per second, both of which are important for military intelligence activities, Taylor said. Greater resolution means the video’s screen can be enlarged without creating a pixilated, or blurry, image, and increasing a video’s frames makes it smoother.
Although ViaSat originally only supplied its satellite connection technology to commercial vehicles, including business jets and trains, the Department of Defense asked the company to adapt its technology to military airplanes.
ViaSat’s satellite antenna and software are installed in more than 100 military aircraft and more than 100 business aircraft, Taylor said. The company is also expanding its reach into boats, and plans to have software in more than 750 maritime craft soon.
The average cost to equip military planes with the antenna and software to transmit videos is about $350,000, and ViaSat also has government contracts to work on upgrading the planes, he said. The company brings in about $50 million a year between its commercial and military customers, but Taylor said that number is expected to grow.
The company’s data rate from the air to the ground is also expected to grow to 2 megabytes “and beyond,” he said. It plans to transition to higher frequency bands and launch a new satellite next year.
DARPA eyes space-based Internet for persistent battlefield data communications, surveillance, and satellite control
Satellite communications experts at the U.S. Defense Advanced Research Projects Agency (DARPA) in Arlington, Va., are taking the next step in developing broadband data communications links to orbiting satellite constellations, not only to establish persistent SATCOM capability for fighting forces in the field, but also to enable real-time control of satellites from military theaters of operation.
The ability to control clusters of satellites from military theaters of operation like Iraq and Afghanistan not only could help establish predictable, round-the-clock satellite communications links for forward-deployed warfighters, but also has the potential to help establish controllable, persistent surveillance capability for the military commanders in the field who need it most.
DARPA awarded an $18 million research contract Friday to Inmarsat plc in London for the Persistent Broadband Ground Connectivity for Spacecraft in Low Earth Orbit program, which seeks to enable near-24/7, very-low-latency, on-demand broadband connectivity between ground satellite terminals and spacecraft in low earth orbit (LEO).
This capability could help establish a persistent communications system for LEO satellites for time-sensitive spacecraft control for defense maneuvers, rapid transmission of critical mission data such as space weather events, direct-from-theater control of spacecraft, and direct-to-theater data delivery with a small ground-based transceiver.
Researchers from DARPA and Inmarsat will use the Broadband Global Area Network (BGAN) service from Inmarsat’s I-4 satellite communications constellation to help develop and demonstrate technology for this program. The BGAN service is the fastest mobile data link available that uses a portable terminal and offers on-demand connectivity with global coverage that could extend to LEO orbital altitudes, DARPA officials say.
The BGAN network, which serves land-based, shipboard, and aircraft satellite communications, provides 492-kilobit-per-second full-duplex, full-channel bandwidth over about 600 spot beams with 588 channels per beam.
A space-based BGAN terminal for LEO use appears to be technically feasible by making modest adaptations to the airborne terminal involving Doppler compensation, radiation hardened components, and software changes for rapid beam-to-beam handover without loss of service, DARPA officials say.
For the Persistent Broadband Ground Connectivity for Spacecraft in Low Earth Orbit program, Inmarsat engineers will design a space-based BGAN terminal, modify the BGAN, perform hardware-in-the-loop tests of a space-based BGAN terminal, and integrate the space-based BGAN terminal with the System F6 fractionated spacecraft demonstration cluster.