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Aerospace

RF Engineering—Bringing Broadband to Everyone

01 March 2017

A few years ago, telling someone that you were a radio-frequency (RF) engineer or encouraging someone to study RF engineering would have produced little understanding, perhaps seasoned with a soupçon of ignorance-borne derision. Yet today, everywhere you look, companies are searching for talented, experienced RF engineers. How has the landscape changed so dramatically? What do RF engineers bring to the party?

For most people today, RF likely qualifies as the least understood engineering discipline. Yet its benefits show up everywhere. To bridge the gap, Bliley Technologies has published a little e-book that sheds some light into the darkness, specifically exploring RF engineers’ critical role in space exploration and—of more immediate concern—in making broadband communication available to everyone on the planet.

Bliley satellite dish.bmp Courtesy Bliley Technologies Bliley satellite dish.bmp Courtesy Bliley Technologies

We in the West take our virtually universal broadband Internet access for granted. By 2020, the number of mobile-connected devices will total 50 percent more than the Earth’s entire population. But many people don’t enjoy such luxury. According to Bliley, 56 percent of the world—more than 4 billion people—have no Internet access. Even in the U.S., some 55 million people cannot enjoy high-speed Internet’s considerable benefits. How do we close that gap?

Overcoming some of the critical stumbling blocks to universal access depends on cooperating with (or at least not violating) the laws of physics. For example, getting wireless broadband to areas with little conventional infrastructure requires deploying an army of orbiting satellites, each addressing a different geographical area. One model for those satellites would park them in geosynchronous orbits so that they could match the Earth’s rotation, remaining in place over one specific spot while expending little energy. But a geosynchronous orbit must reside above the equator at an altitude of about 22,300 miles. Besides making the satellite(s) large and expensive, as well as difficult to launch or retrieve for repair or enhancement, the distance produces a minimum theoretical latency (lag time to the Earth's surface at the speed of light) of 125 ms. Round trip, each message would take ¼ of a second to reach a recipient. That small delay may not seem like much, but if you string enough ¼ seconds together, they add up.

Alternatively, deploying a collection of satellites in a much closer low-Earth orbit (LEO) reduces round-trip time to perhaps 1 to 4 ms, making the rhythm of conversations between satellites and ground stations much more natural. Keeping such satellites in orbit requires thrust out of sync with the rotation of the Earth. A satellite might complete an orbit (as the International Space Station does) in just 90 minutes, so it cannot remain fixed over a single geographical area.

Controlling stations must compensate for that movement. Some engineers have called for creating a network with a small number of conventional satellites. But such satellites are expensive and logistically difficult to build and maintain. They require launching one at a time, so launching enough of them to construct a communication net would likely take at least several years.

In contrast, one model for LEO satellites championed by Elon Musk calls for thousands of tiny inexpensive craft that cover the territory in a predefined pattern. A single launch could deploy many of these so-called “swarm” versions, dramatically limiting the number of launches to create a complete coherent network and reducing construction time to less than 18 months. Sending up more objects than necessary permits overlapping them to prevent gaps and minimizes the chance that loss of a single craft would compromise anyone’s Internet coverage. The network could orchestrate routing logistics so that affected areas on Earth do not experience intermittent outages. No one would take the trouble to repair faulty systems. Instead, they would fall back to Earth and burn up in the atmosphere long before they caused any damage, while space agencies would launch new ones to replace them quickly and at little cost. A number of companies have already begun planning such nets.

The plan has drawn detractors, even among the engineers themselves. Until now, the tiny satellites have performed only routine operations (such as assembling a short-term radiation map of the planet) because in the projects to date the tiny satellites have remained in orbit for only a short time, and engineers have observed that their orbits often fall out of sync with one another.

Because communication between a satellite and the Earth relies on radio-frequency communication, projects like these require the expertise of RF engineers. They create schematics for both ends of communication systems. The schematics allow astronauts or others stationed away from the technological infrastructure to service cell phones or other broadcasting devices without requiring resources from the Web. Network setup designs would map processes for handling and prioritizing data traffic. After network deployment, the engineers would perform routine maintenance from the ground to ensure peak performance, identifying the cause of any failures and correcting them. Constant monitoring and frequent adjustment would ensure that small orbit and velocity deviations wouldn’t compromise communication efficiency. The engineers would also lend their experience and expertise to planning future techniques and products to carry the technology forward.

So the next time you use your broadband Internet from your smart phone or computer, thank an RF engineer. You may not know who designed your tools, but RF engineers made up a major part of the team.

Sources:

Low Earth Orbit Satellite Verses [sic] Geostationary Satellites…The Differences?

The Role of RF in Bringing the Internet to the World

Elon Musk shares details of Internet satellite swarm dream



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