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The Big Bounce

New power for the tech that ricochets signals off Earth’s atmosphere

Tropospheric scatter radars use particles in the Earth's atmosphere as reflectors for microwave radio signals.

It can be tough to get a good cellphone signal in Afghanistan.

The entire country has fewer than 5,000 active cell phone towers and is distinguished by its rough, mountainous terrain.  That makes communications challenging for U.S. military members in-country, since traditional radios work via “line-of-sight,” meaning signals can be blocked by ridgelines and ranges. And satellite communications are very costly.

That’s where tropospheric scatter, or troposcatter, technology comes in. It uses particles in the atmosphere as reflectors for microwave radio signals. Aimed just above the horizon in the direction of a receiver station, signals pass through the troposphere, where some of the energy is scattered back toward the Earth. Receivers capture the signals after they bounce off the atmosphere.

“Troposcatter fits an interesting niche,” said Cedric Vigil, Raytheon’s troposcatter program manager. “Tropo doesn’t replace radios, fiber or satellite communications. It’s another tool for network planners to use when the conditions warrant it.” 

Troposcatter delivers beyond-line-of-sight communications up to a distance of about 200 miles, providing secure, reliable wireless data networks with 100Mbps data transmission speeds almost anywhere in the world, regardless of terrain or operational conditions

The military has been using some form of troposcatter since the early 1950s, but now that much more advanced technology is available, the U.S. military is looking to upgrade.

“Not only does troposcatter save the service money, it also serves a very important strategic function,” Vigil said. “It offers a bigger pipe for data—more than satellites supply—as well as less latency. In combat, milliseconds count.”

Raytheon's modern troposcatter capitalizes on the company's gallium nitride-based semiconductor technology, which delivers superior performance. Raytheon troposcatter is offered in vehicle-mounted equipment as well as a portable, grab-and-go system. The latter comes in as few as three cases, and can be up in running in less than an hour. The system automatically establishes the link with a push of a button.

That marks a big improvement over the military's older systems, which require “the operator to align the antennas at both ends,” Vigil said. “Imagine trying to get the rabbit ears just right on your dad’s old TV and then having somebody on top of the TV station tower trying to point its transmitter at your rabbit ears 80 miles away. ‘OK…now a little bit to the left…wait, go back a little…’ That’s what it used to be like.”

Raytheon Troposcatter systems capitalize on the futuristic capabilities of gallium nitride-based circutry.

Vigil said gallium nitride technology allows troposcatter systems to be significantly smaller and much more portable than older equipment. The new radios also have touchscreen graphical user interfaces.

“It’s very simple and very intuitive to use, and troubleshooting the system is a breeze,” Vigil said. “Our goal was to minimize the complexity and minimize the amount of training needed to run it. Really, once it’s set up and running, then you just leave it alone until you’re ready to break it down.”

The system is ideal for austere conditions, according to Vigil, where internet and communication access is nonexistent, or spotty at best.

“If there’s an internet connection about 100 feet down the road, then you can dig a trench and run a cable,” Vigil said. “But if that internet connection is 100 miles down the road, then that’s when troposcatter technology can save the day.”

Troposcatter is almost like a water main for any type of Ethernet traffic. Soldiers can set up voice, video, data and wifi networks. They can also collect intelligence from drones, and electro-optic and other sensors.

“It will integrate with any number of comms and sensor packages,” Vigil said. “It allows commanders to get a clearer picture of the battlespace, managing their assets and helping protect our forces.”

This document does not contain technology or technical data controlled under either the U.S. International Traffic in Arms Regulations or the U.S. Export Administration Regulations. E16-Y2T4.
 

Published: 09/27/2016

Last Updated: 12/01/2016

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