VSATs supply global sky links
- By Gregory Slabodkin
- Feb 23, 1998
The need for flexible and affordable bandwidth is pushing the Army to use a new global
commercial satellite communications service for two-way telemedicine applications.
The Telemedicine and Advanced Technology Research Center (TATRC) at Fort Detrick, Md.,
recently awarded a $1 million contract to Hughes Global Services Inc. of Los Angeles.
The company, a new unit of Hughes Electronics Corp., will provide the Army with 11
transportable, very-small-aperture terminals (VSATs) and a year's worth of full-duplex
DemandNet bandwidth services.
The Army is the first service to use DemandNet, but TATRC is a tri-service organization
whose role includes evaluating new technology for other services. As its need for
integrated voice, video and data imagery grows, the military will increasingly rely on
commercial satellite communications systems such as DemandNet.
The system supplies worldwide duplex communications over the Hughes global satellite
constellation and ground gateways such as fiber backbone, the Internet, public switched
telecommunications network access and VSAT terminals.
The Army wants DemandNet to deliver bandwidth on demand at rates of 64 kilobits/sec to
2 megabits/sec per site. The Army, however, does not expect to exceed 1 megabit/sec at any
The Army bought 11 portable VSAT terminals--two C-band and nine Ku-band space
The Ku-band terminals give higher data rates with smaller antennas. But Ku-band
coverage is nonexistent in Africa, South America and the oceans. That's where the hybrid
C/Ku-band comes in.
Six of the 11 VSAT terminals will be deployed to Bosnia to support military hospitals
there, allowing the Army to use voice, high-speed data, Ethernet and Integrated Services
Digital Network services.
"One of the applications the Army wants to do is an ISDN, slow-scan video from the
field that will transmit these images to a hub and then distribute it out to a third
party, such as a medical specialist," said Dave Kelly, Hughes' DemandNet products and
The system will not only let soldiers in the field send and receive medical data, such
as patient records and X-rays, but also let doctors in the field consult with physicians
and medical experts in distant medical facilities via teleconferences.
"We have telemedicine deployments scattered all over the world that require the
ability to move bandwidth around," said Col. Bob Vandre, TATRC's device sciences
DemandNet is flexible. The network bandwidth can be reallocated, expanded or moved
within the Hughes global satellite system on an as-needed basis.
Soldiers need only make a phone call to DemandNet's Bandwidth Management Controller
center to change the bandwidth quantity, distribution and location.
"It's basically a VSAT system, but the clever part we put together is that we are
hosting the service on the entire constellation of PanAm satellites. What we offer is a
lot of flexibility in bandwidth with a simple phone call," Kelly said.
The Army is using the system through PanAmSat 1 for communications on the East Coast of
the United States. When it deploys the terminals to Germany and Bosnia, the system will go
through PanAmSat 3, Kelly said. If the Army expands the system into the Pacific, it can
use PanAmSat 2.
The idea is to buy a bandwidth pool that can move to different areas," he said.
Portability is not DemandNet's strong point, however.
Initial setup is more difficult than that of the SATCOM system the Army has used.
DemandNet antennas or terminals, bundled for transport, can weigh almost 500 pounds. The
satellite dishes at the VSAT terminals are 8 feet in diameter. The dishes for the
International Maritime Satellites, by comparison, are 3 feet in diameter.
INMARSAT equipment weighs only 40 pounds and is portable. But it is expensive: 64
kilobits/sec costs about $9 a minute.
In Bosnia last year, the Army spent nearly $1 million to use 11 INMARSAT terminals. It
used it for an average of 10 minutes per day at 64 kilobits/sec. Vandre said the same $1
million would have given the Army the use of DemandNet at 256 kilobits/sec around the
clock for a year.
Hughes Global Services was created to give federal, state and local governments access
to DemandNet satellite telecommunications services.
In addition to the VSAT terminals, Hughes will provide system engineering, integration,
installation, training, maintenance and a help desk.