Inside GNSS: Washington View: AAM Navigation

NextNav was recently featured in an Inside GNSS article about Advanced Air Mobility and the need for resilient PNT in this industry, and Inside GNSS spoke with NextNav CEO Ganesh Pattabiraman. From the article:

NASA is seeking PNT requirements for advanced air mobility when GPS is not available, but the ultimate solution may come in many forms.

At the recent FAA AAM Summit, NASA’s Parimal Kopardekar, one of the main movers in the advanced air mobility field, was asked to name some of the top operational challenges facing AAM in the near term.

One part of his answer: the need for alternative position, navigation and timing (PNT) to buttress GPS, particularly for autonomous aircraft.

“There are places, particularly urban areas, where there’s multi-path error, GPS is not reliable or is not available,” Kopardekar, universally known as PK, told Inside GNSS in a separate interview. “We would need solutions to be reliably operated in those conditions. There are companies working on it, we are working with a number of alternatives.”

The agency isn’t developing technology on its own, or even moving to select any particular technology, but is instead working to define the requirements for such a system or systems.

“There are a number of good companies and technologies,” he said. “One of the things we are interested in identifying is, what are the requirements for operating in an urban airspace for these alternatives to GPS? We don’t choose technologies, but we identify what the requirements are.”

Possible solutions could be anything from satellite-based systems to ground beacons, or even combinations of multiple systems, he said. Not all the systems are coming from companies with a traditional aviation background.

“There are some traditional aviation, there are some nontraditional aviation, we are working with one SBIR company called Higher Ground, but there are many others,” he said, including NextNav. The company uses terrestrial transmitters, which are essentially ground-based beacons.

NextNav, based in Sunnyvale, California, has had its beacon system—named TerraPoiNT—evaluated by the U.S. Department of Transportation, NASA and the European Union’s Joint Research Centre.

“We’ve worked with NASA historically…we got the first NASA contract at Langley Virginia, where we deployed a dedicated system around Langley campus to characterize urban drone operations, so they’ve been using it and testing it since 2018 at that facility,” said Ganesh Pattabiraman, the company’s founder and CEO. In late 2022, NextNav announced NASA would use its system for urban air mobility PNT at Ames Research Center.

“Clearly, the system meets many of the requirements they believe are required for future AAM operations,” Pattabiraman said.

He described the hardware as looking like a dorm room refrigerator with an antenna on top, operating nationwide in the company-owned 920-928 Mhz band. “You trilaterate from four of them to figure out your location,” he said. “We’re able to give you position, navigation and time,” the latter from atomic clocks in each transmitter.

The system provides three to four meter vertical accuracy 94% of the time, and for 2D positioning in the five to seven meter range, or better. For on-route operations, “that’s plenty,” he said, although for takeoff and landing greater precision would be required and could be provided by other systems or by installing a beacon at a vertiport.

The system provides GPS-like service in areas, such as urban canyons, where GPS may be blocked or where it could be jammed.”

Read the full article on Inside GNSS here.