Air Force tunes in radio for e-mail link
- By Bob Brewin
- Sep 12, 1999
The Air Force soon could use one the oldest forms of telecommunications - high-frequency (HF) radio - to provide e-mail worldwide to its aircraft, including Air Force One, at a cost far lower than satellite links.
The House inserted an extra $3.8 million into its version of the fiscal 2000 Defense Department appropriations bill that will provide funding needed to add HF e-mail capability to an ongoing upgrade of the Air Force's System Capable of Planned Expansion Command global HF network.
Chief Master Sgt. Glyn Howell, SCOPE Command deputy program manager at the Air Mobility Command, said that the added funding will allow his organization to leverage the global HF network to provide "data link capability from the desktop to the cockpit.''
The SCOPE Command network consists of upgraded ground stations and advanced radios in aircraft that connect to DOD's Non-Classified Internet Protocol Router Network (NIPRNET). It bounces signals in the bands from 3 MHz to 18 MHz off the atmosphere to provide connectivity from ground stations to distant aircraft.
The HF network could produce substantial savings compared with satellite communications, Howell said. Satellite communications require high up-front investments regardless of whether DOD launches its own satellites or leases space or time on commercial systems. And Howell noted that AMC pays for each call on its existing satellite service, but the HF system "is free, and users do not have to pay a charge.''
Rich Moseson, editor of the ham radio magazine CQ, said the SCOPE Command project continues the Air Force's pioneering use of HF. Moseson said that the legendary Gen. Curtis Lemay, head of the Strategic Air Command during the Cold War, was a ham operator who pushed the use of single-sideband HF in the ham community, with an eye toward the Air Force adopting it.
HF radio, despite some of its technical limitations, can meet the demands of the Digital Age, Moseson said. "It's still possible to innovate in HF," he said. "There's a lot that can be done with digital signal processing - and not just data but voice."
Steve Valvonis, assistant proj-ect manger for HF systems in the Advanced Automated Tactical Communications Program Office at the Space and Naval Warfare Systems Command, glowingly summed up the attractiveness of HF communications to federal users with a play on the words "government-furnished equipment" (GFE), a phrase found in many government contracts. "We call HF GFE, but to us it stands for God-furnished equipment,'' he said.
On the downside, Howell and Valvonis acknowledged that HF signals are inherently noisier than satellite signals, causing a reduction in data throughput. Howell said AMC can achieve a "very good" HF data link at 2,400 kilobits/sec but added that it will not be difficult to achieve 4,800 kilobits/sec in the future.
The SCOPE Command upgrade, being performed by Rockwell Collins Inc., also will make HF radio easier to use, according to Howell.
For years, HF communications "was more of an art than a science,'' because variables such as the time of day (HF signals travel better at night) and sun spot activity required the intervention of a skilled operator. Operators had to monitor the performance of particular frequency in a particular part of the globe and then switch to another frequency as performance degraded on the initial frequency.
Howell said Rockwell Collins has built into the new SCOPE Command radios a technology called Automatic Link Establishment, which provides computer-driven scanning of available frequencies. The computer then builds a database of the frequencies that provide the "best contacts" and then puts them into a database in the radio. Compared with manual tuning methods, ALE "provides us with a 95 percent connection reliability," Howell said.
"The system is constantly checking frequencies, assigning weights to those with the best connectivity and then using them," Howell said.
Besides helping to select the best frequency, ALE also helps determine the best SCOPE Command ground station for an aircraft to connect with, Howell said. Once an aircraft connects with the ground station, the incoming signals are fed automatically into a specialized digital switch manufactured by CML Technologies Inc., Hull, Ontario. The switch patches the signal into DOD's worldwide voice or data communications networks.
The Navy has not installed the ALE HF gear as widely as the Air Force, but Spawar's Valvonis said the service plans to increase its use of the technology.
"The next years will see an increase in funding for HF because of the need for allied interoperability,'' Valvonis said, adding that foreign navies and air forces do not have the wealth of satellite assets available to U.S. forces and still rely heavily on HF.
The Navy, for example, used HF to routinely send e-mail to Australian ships participating in the last two Tandem Thrust exercises in the South Pacific - technology demonstrations that could meet a real-world test if United Nations troops led by Australia engaged in peacekeeping operations in East Timor.
Though an old technology, HF radio has a bright future within DOD, according to Howell.
"We see a long future for HF systems," he said. "With continued upgrades, [SCOPE Command] is good for another 20 years."
Who gets help from HF radio
The Air Force SCOPE Command project provides upgrades to high-frequency ground stations at Andrews Air Force Base, Md.; Offutt AFB, Neb.; a West Coast station; Hickam AFB, Hawaii; Anderson AFB, Guam; Diego Garcia; Ascension Island; Thule Greenland; Croughton AFB, England; Lajes Field, Azores; Incirlik AFB, Turkey; Yokota AFB, Japan; and Puerto Rico.
The following stations will support four distinct networks:
* U.S. Air Force Global, which supports a wide range of Defense Department users by providing air-to-ground, ship-to-shore links to users in all four military services.
* Mystic Star, which provides high-frequency communications for the president aboard Air Force One and other high-ranking government officials when flying on Special Air Mission Aircraft.
* The Information and Telecommunications System of the American Air Forces Radio Station, which is a bilingual (Spanish/English) voice and data network serving the United States and allies in North America, Central America and South America.
* Defense Communications System HF entry points, which provides communications services for tactical units deployed worldwide.