Ground Segment Aims to Fly High in the New Space Environment

Smallsats, new orbits, and mega-constellations have revolutionized the satellite industry space segment in recent years. The pace of technological change has led some to question whether the ground segment can keep up. But away from the spotlight, a series of innovations in antenna technology, waveform processing and system design have been quietly starting a revolution down on Earth, as well.

“A lot of time and energy and money has been invested in the new satellite constellations,” points out Carl Novello, CTO of NXT Communications Corp. (NXTCOMM), an Atlanta, Georgia area-based startup. But on the ground, he adds, the situation looks very different.

“Not enough focus and energy has been placed on the ground segment and in particular the terminal,” the device which connects the end user with the satellite, Novello argues. This is particularly important given the technological shift from the world of Geostationary Orbit (GEO) satellites to a Low-Earth Orbit (LEO) and Medium-Earth Orbit (MEO) world, where many satellites move across the sky.

That makes things significantly more complex, Novello says. “Even for those of us who have worked in the mobility product space where that terminal on the ground has to be able to move in relation to the satellite, this adds another dimension: It’s not just that the terminal is moving, but the satellite is too.”

In the new multi-orbit world, he says, the biggest challenge on the ground will be flexibility. Traditionally satellite operators have been tightly vertically integrated, with terminals designed to work with a single constellation across a relatively narrow portion of spectrum. With operators adopting a multi-orbit approach, that increasingly won’t cut it.

“The challenge is how do you move from being a product that is relatively fit for a single purpose to becoming the Swiss Army knife of antennas?" Novello asks. "One that will work in GEO use cases and LEO use cases and MEO use cases, with different requirements for frequency bands, uplink power, different regulatory requirements to meet, and so on.”

In other words, concludes Novello, “How do we build a better antenna fit for this brave new world of satellite connectivity?”

That’s what NXTCOMM and other satellite technology providers are working on. The company uses a technology called fragmented aperture, which tackles some of the underlying physical limitations of a conventional flat-panel or phased array satellite antenna. Fragmented aperture uses complex, pixelated structures for its radiating elements, to reduce interference and boost efficiency.

NXTCOMM is already gearing up to start production of its new antennas. Next year, L3 Harris will start to use them in both manpack and flyaway terminals for an undisclosed U.S. Department of Defense customer.

A Paradigm Shift in Antennas

Fragmented aperture is just one new technology aiming at the dramatic performance improvements needed for the ground segment to keep up with the new multi-orbit world.

Another company seeking to build a better mousetrap is Hawthorne, California-based ThinKom Solutions, whose variable inclination continuous transverse stub or VICTS phased-array technology combines the technical benefits of mechanically steered and Electronically Scanned Arrays (ESA), according to Bill Milroy, chairman and CTO. “We get the best of both worlds,” he says.

In simple terms, VICTS technology is comprised of parallel plates or discs rotating relative to each other around a single axis to steer the beam and control polarization. For space-based antennas, the plates are aluminum, and ThinKom is exploring using additive manufacturing for these. In ground-based products, the company uses metalized plastic. VICTS uses a contactless circumferential drive to move the plates like a maglev train, says Milroy. “It’s a contactless inductive drive, so if you look inside, you don't see a motor, you don't see gears, you don't see pulleys, you don't see belts.”

That gives the technology big advantages, Milroy says. The contactless drive is more reliable than either conventional mechanical movement systems like gimbals or the non-mechanical ESA antennas. He cites statistics from the company’s airborne VICTS antenna product line, that with 22 million flight hours over six years, the mean time before failure is well north of 100,000 hours. ThinKom’s parallel plate technology aims to increase scan range, reduce power requirements, improve on performance efficiency, and is lower cost.

Cost savings like that are going to be an increasingly important differentiator in the new markets and verticals the multi-orbit world will open up including mass-scale use cases for consumers or even Internet of Things (IoT) applications.

“Price and price elasticity in the terminals and antenna providers is going to be key to getting into those markets,” Milroy explains, because they are potentially logarithmically larger than the current market base. “We may need to see prices reduced by an order of magnitude, which is bad for us as suppliers. But the reward is the market size, it could be orders of magnitude greater.”

Milroy says the company can force its unit costs downwards if a customer wants to buy 10,000, or 100,000 antennas. New technologies like additive manufacturing, more commonly known as 3D-printing, will also help, he says. “We think our antennas are ideally suited for additive manufacturing, which is kind of a hot topic. We're doing some really interesting experiments in that area.”

Automation and Integration

Working with cutting edge technology is at the center of the business model for Comtech Xicom Technology, says Vice President of Sales Eric Schmidt. The company, which has been making signal amplifiers and block upconverters for 30 years in Santa Clara, California, is focused on improving its products to meet the more rigorous demands of the new multi-orbit world, like the extremely high frequency Q- and V-bands.

“Our R&D philosophy is to focus on the underlying technology, the fundamentals, for instance of circuit design, to deliver the best performance,” he says. “We spend a lot of R&D money on the technology and the infrastructure, as opposed to the way some companies do it, where they're essentially providing a company subsidy to underwrite the development of new products. In our case, we start with trying to build a new foundation — the technology — and then build the products on that.”

Over the next decade or so, Schmidt says automation and integration will be key differentiators in the ground segment, as new constellations require growing numbers of ground stations, some in remote locations.

“Reducing the footprint, reducing the power consumption, reducing the maintenance burden … That’s going to count for more and more,” he says. “I think the trend is more and more towards complex and increasingly autonomous systems that are fully integrated, so the system itself can automatically increase power, change waveform, change modulation, change coding or whatever is needed for the link condition that the system itself senses.”

Singapore-based ST Engineering iDirect has already made strides towards that vision of a self-managing signal. Seven years ago, the company pioneered its Mx-DMA, a milestone waveform technology which upended the return link market — the way the terminal talks back to the satellite. This year, the company unveiled the second generation of that waveform technology: Mx-DMA MRC (for multi-resolution coding).

“The difference is scalability,” explains ST Engineering iDirect CTO Frederik Simoens, “You have a lot of users, they're all transmitting to the satellite, but you have to orchestrate all those transmissions to make sure they're not overlapping. To dynamically allocate resources to make sure everyone has the bandwidth they need, you have to do it automatically. It's about the ability to scale that, to achieve the highest throughput per user, but also to achieve the fact that you can have many thousands of users with very different use patterns and bandwidth demand transmitting at the same time, all using the same platform. Coping with all of that is what this new generation Mx-DMA MRC technology does.”

In addition to the efficiency benefits the new return waveform offers, says Simoens, there are operational benefits, too. “As an operative, you don't have to configure carriers, you don't have to configure modulation schemes, it's just handing out a bunch of spectrum slots through the system, and the system will take care of assigning them automatically.”

Is Software Eating the Ground?

One big enabler of automation, Simoens says, is virtualization. “With software-defined networking, it becomes possible to automate and orchestrate a lot of the things that used to be manual, like configuring a network for a new beam. That used to be a manual action, but now it can be fully automated, because of that network function virtualization. This is the future.”

And network switches aren’t the only kind of hardware in the ground segment that’s destined to go the way of the floppy disk drive, according to Stuart Daughtridge, vice president of Advanced Technology in Kratos Space, Training, and Cybersecurity division.

The company’s Open Space platform offers a set of virtual tools for ground segment management, based on an extensible, open and totally software defined architecture. “It's enabling that move from legacy analog infrastructure to a digital and software-defined infrastructure,” he says.

Nonetheless, virtualization isn’t entirely complete, and frequencies higher than 6 gigahertz have to be converted by a piece of analog hardware called a frequency converter.

“Eventually though, as digitizers get better, the technology gets faster, you'll continue to be able to digitize at higher and higher frequencies, so that you'll get rid of the frequency converters,” Daughtridge explains. “The bottom line is, your amplifiers will stay hardware, your antennas will stay hardware and your satellites will stay hardware, at least on the outside. Pretty much everything else in between gets virtualized.”

And that’s a good thing, too, argues Chris Boyd, senior director for product management in Kratos Space, Training, and Cybersecurity division.

“When things were all hardware, if you wanted to roll out a new capability, you’d have to lay cable, you’d have to provision new hardware. It would take weeks or months. With virtualized network functions that demand cycle can be closed a lot quicker. With Open Space we can satisfy that demand very much like how big IT networks are managed today, getting it down in some cases to minutes," he says.

And that flexibility gives Open Space users the ability to support more dynamic services for their customers, Boyd points out, which means more opportunities to monetize the capabilities of new satellite constellations.

"The capabilities are amazing but at the end of the day, you need a dynamic and flexible ground system to be able to monetize that. And that means software defined," Boyd says. VS

Shaun Waterman is a freelance journalist based in Washington, writing about cybersecurity, government IT, emerging defense technologies, and space.