TRW Digital Processing and Antennas Boost Battlefield Capability of Milstar II Satellites.

Business Editors & High-Tech Writers

REDONDO BEACH, Calif.--(BUSINESS WIRE)--Feb. 19, 2001

Milstar Flight 4, set to launch Feb. 24, carries TRW-built high-speed, on-board digital switching and antennas that automatically counter enemy signal jamming.

In orbit, these new technologies will make Flight 4 the first satellite to deliver secure, on-demand mobile broadband communications to U.S. warfighters.

The advanced TRW technologies are part of a new medium data rate (MDR) communications payload, debuting on Flight 4 (for photos and more information go to the Milstar Flight 4 News Center). The ability to communicate at MDR speeds enables the latest Department of Defense Milstar satellite to provide high-speed transmission of maps, reconnaissance data, and other digitized, tactical information to commanders and troops in the field. Two Milstar satellites currently in orbit communicate at much lower data rates.

"This launch brings 21st century data capabilities to American forces," said Rick Braun, TRW's Milstar payload program manager. "The TRW-developed fast digital switching and nulling antennas of Milstar Flights 4 through 6 will permit U.S. military forces anywhere on Earth, equipped with only small terminals, to communicate securely at rates as high as 1.544 million bits per second (Mbps). That's roughly 30 times faster than the modems on most personal computers today."

The low data rate (LDR) payload aboard Milstar Flights 1 and 2 (referred to collectively as Milstar I) transmits data at a maximum rate of 2400 bps. Flights 4 through 6 (known as Milstar II) will fly both an MDR and LDR payload. The LDR payload provides highly robust, global communications links under even the most severe battle conditions, ensuring high-security support for the U.S. Department of Defense's strategic mission.

Lockheed Martin Space Systems is system integrator and contractor to the U.S. Air Force for the joint-services Milstar program. Boeing Satellite Systems integrates the MDR payload for Lockheed Martin, while TRW is subcontractor to Lockheed Martin for the LDR and supplies Boeing with MDR antennas and the digital processing subsystem.

On-board Digital Processing

Key to Dynamic Milstar Communications Milstar's LDR and MDR payloads function as "switchboards in space," providing users with circuits on demand. This digitally controlled approach allows easy reconfiguration of satellite resources to meet constantly shifting requests for service from rapidly changing user networks. Digital signal processing also enables use of spread-spectrum techniques that help defend Milstar signals from jamming.

Milstar is the first satellite system to operate only at extremely high frequencies (EHF), with uplinks at 44 GHz and downlinks at 20 GHz. Operating at EHF yields a number of benefits, including the ability to produce narrow spot beams. These spot beams provide higher gain, permitting the use of smaller, easily portable Earth terminals with small antennas. The smaller area of beam coverage drastically lowers the probability of the Milstar signal being detected or intercepted by enemy forces.

Advanced Antennas Foil Jammers, Serve Dispersed Users

The MDR's two nulling spot beam antennas instantly detect enemy signal jamming and counter it within a fraction of a second by placing a "null" in the jammer's direction. (In antenna terminology a "null" is a direction from which an antenna collects very little energy. The null minimizes the strength of the jammer's signals, while maximizing the strength of Milstar users' signals.) These nulling antennas are the first ever to perform nulling autonomously, with no commands from the ground. The nulling capability is vital for theater applications, where jammers may be located close to Milstar users in the same antenna coverage area.

Complementing the MDR nulling antennas are six distributed user coverage antennas (DUCAs). DUCAs better match the needs of dispersed global users such as the U.S. Navy, whose ships are less likely to be near jamming stations.

The DUCAs incorporate important advances in manufacturing techniques. The payoffs: TRW was able to lower costs by more than 60 percent and slash weight by 72 percent as compared with the counterpart antennas on Milstar I satellites. The weight savings provided some of the margin needed to achieve the MDR's greater data rate and nulling capabilities.

Beyond Milstar, in May 2000, TRW joined with Lockheed Martin and Boeing Satellite Systems to form the Advanced Extremely High Frequency (Advanced EHF) National Team to build the follow-on to the Milstar highly secure communication satellite program. Formation of the team accelerates development of the new system by 18 months. The earlier deployment of Advanced EHF will help bridge the gap in military communication coverage caused by the loss of the third Milstar satellite, launched in 1999.

Under the National Team arrangement, TRW will design and produce the Advanced EHF satellites' digital processing subsystem, which controls all on-board switching and processing of messages. TRW will also provide the satellites' nulling antenna subsystem, which prevents adversaries from jamming signals to and from the satellite, and the intersatellite crosslinks with support from Boeing for the crosslink reflectors. Crosslinks enable Advanced EHF satellites to send messages directly to each other, without the need for a ground station. First launch is planned for 2004.

TRW Space & Electronics Group is a global leader in the development of digital, broadband space communications payloads for defense and commercial customers. It is an operating unit of TRW Inc., which provides advanced technology products and services for the automotive, space and defense, telecommunications and information technology markets worldwide. Information about the company is available at www.trw.com.