TROPO is the ability to transmit radio waves over the curvature of the Earth, without using satellites, by bouncing signals off irregularities (small changes in humidity, temperature and pressure) in the troposphere, approximately 6.2 miles (10 kilometers) above the Earth's surface. The U.S. military currently employs TROPO systems for tactical and strategic communications throughout the world.

In partnership with General Dynamics, Raytheon successfully established its industry-first 20 MBps (megabytes per second) Ku band TROPO or "over-the-horizon" communications link operating in the Ku band.

The link operated for several months and in varying weather conditions between Raytheon's Pelham, N.H., test facility and the test facility of the 267th Combat Communications Squadron at Otis Air Force Base, Cape Cod, Mass.

The demonstration, using modems developed by Radyne Corporation, more than doubled the bandwidth of current available TROPO systems. Increased bandwidth enables soldiers to transmit and receive greater amounts of video and voice data information more quickly.

This communications milestone was achieved using Raytheon's newly-designed Dual Mode All Band Relocatable Communications Transport Terminal (DART-T), a highly transportable, self-contained terminal, configurable for operation in satellite, TROPO and line of-site-modes.

The DART-T uses a single antenna with a dual-beam feed system, rather than the two antennas used on today's TROPO systems, making it significantly more portable. Currently fielded tactical satellite communication and TROPO terminals have a larger footprint and require up to six transport vehicles for the same capabilities that DART-T provides with one vehicle.

From a logistics standpoint, DART-T's smaller footprint is critical because fewer vehicles and aircraft are needed for transport to soldiers in the field.

The DART-T also has auto acquisition, replacing the traditional manual alignment of the antennas. Auto acquisition means faster set up in the field and less training for soldiers who today use manual acquisition systems.

Jerry Powlen, vice president, Integrated Communications Systems, said: "In the midst of battle, the warfighter needs instant access to information. This solution offers all branches of the military an alternate form of secure and reliable communications and reduces the demand for satellite bandwidth."

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