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Complementary PNT Takes Center Stage

Of the 60 exhibitors at the Institute of Navigation’s Joint Navigation Conference (JNC) in San Diego this year, 16 make inertial navigation systems (INS). Many of the other exhibitors integrate INS with GNSS receivers or make simulators to test those integrations. Several exhibitors make a variety of other navigation systems, using active and passive optical sensors, wheel encoders and RF systems that map beacons of opportunity. Only seven manufacturers of GNSS receivers were present.

That’s because the conference — which took place June 6-9 and focused on technical advances in positioning, navigation and timing (PNT) — was hosted by ION’s Military Division for the Departments of Defense (DOD) and Homeland Security. “From an operational perspective,” said the conference program, it focused on “advances in battlefield applications of GPS; critical strengths and weaknesses of field navigation devices; warfighter PNT requirements and solutions; and navigation warfare.” In other words, it was mostly on how to navigate in environments in which the use of GNSS is challenged or denied due to jamming.

The conference program told the story of the GNSS/PNT community’s interests and concerns. Several sessions were on complementary PNT using terrestrial RF signals of opportunity, IMUs, geophysical fields (including gravity and Earth’s magnetic field), celestial objects, ground vision and new commercial sources of space-based PNT, such as satellites in low Earth orbit (LEO).

Other environments in which reliance on GNSS is hard or impossible — such as urban canyons, deep inside buildings, underground and underwater — pose the same navigation challenges to both military and civilian applications. Likewise, jamming is a threat to both. Therefore, several sessions focused on critical infrastructure, demonstrating that the concerns about GNSS vulnerabilities are not just military ones.

Hence the presence among the exhibitors of three manufacturers of atomic clocks, which continue to shrink in size, weight, power and cost (SWaP-C) and are used to assure holdover — that is, the time period required to keep networks synchronized when their primary timing source, usually GNSS, is disrupted or temporarily unavailable. Networks affected include cellphone providers, radio and television broadcasters, financial networks, and the biggest network of all, the Internet.

The JNC “experienced record attendance in both conference participants and exhibitors, hosting more than 1,000 attendees,” Lisa Beaty, ION executive director, told me. She attributed the increase to “the importance of PNT in the nation’s critical infrastructure, current innovation, programmatic funding, and the desire by the DOD community to collaborate and reconvene.” She confidently anticipates additional growth next year.

I am equally confident that much of the cutting-edge technology on display at this conference will find its way into civilian applications in the next few years. Whether in war or in urban canyons, GNSS navigation faces some of the same challenges.

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