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Double trouble: GNSS over-reliance and its costs

June 28, 2017  - By

This month’s column deals with two troublesome topics: the U.S. government’s over-reliance on GPS, and the potential costs of GPS disruption toward which such a policy may be leading us.

First things first.

When someone utters the words “I’m nearly perfect,” get on your toes. Such self-appraisal usually masks something. It could be insecurity, denial, ignorance or simply fear. At the very least, some level of illusion, if not delusion, is involved.

With that precept in mind, let’s examine a June 16 press release from the U.S. Air Force, under the headline “New reports confirm near-perfect performance record for civil GPS service.”

The press release actually says, “The U.S. Air Force released two technical reports demonstrating that the Global Positioning System (GPS) continues to deliver exceptional performance to civilian users around the world….The 2014 and 2015 performance reports confirm that the GPS Standard Positioning Service (SPS) satisfied nearly all measurable performance commitments documented in the GPS SPS Performance Standard.”

Fair enough. Those are demonstrable facts. Nowhere does the release — other than in its headline — employ the words “perfect” or “near-perfect.”

The problem is, as current events repeatedly show, people remember only the headline. That may be all that they read or register in the first place.

Affixing the label “near-perfect” to GPS is “potentially dangerous,” points out Dana Goward of the Resilient PNT Foundation, “because it could exacerbate the public’s growing over-reliance on, and often blind faith in, GPS.  Even if GPS did always perform perfectly, all kinds of things can happen to signals after they leave the satellites and before they get to receivers. Personal privacy devices, other jammers, spoofers, solar activity, other electromagnetic interference, even the local geography can significantly degrade or disable a receiver’s performance. That’s why in the GPS System Performance Standard the Air Force specifically says its responsibility ends once signals are in space.”

Perfection might exist in space, but it doesn’t down here.

Even in space, accidents sure will happen. The Air Force release documents GPS performance for 2014 and 2015. This conveniently draws up short of January 2016, when several GPS satellites broadcast a timing error that triggered equipment faults and failures globally for nearly 12 hours. Thus demonstrating something far from perfection.

Issuing a statement in the manner done on June 16 perpetuates a dangerous myth, keeps users in the dark about the actual state of affairs, cultivates a What-Me-Worry? approach to positioning, navigation and timing, and abets the lack of political will and understanding of GNSS vulnerabilities.

We have expanded the focus of this magazine to cover other technologies relevant and applicable to the field precisely because GPS, and by extension GNSS, great though they may be, are not perfect. Not even nearly.

At What Cost Ignorance?

A report recently compiled and released in the UK attempts to quantify the cost of a GNSS disruption, should one occur.  The figure the authors came up with? 1 billion pounds sterling per day.  That’s approximately $1,273,710,000.

Per day.

The report, available in either 11-page or 133-page versions, and titled The economic impact to the UK of a disruption to GNSS, looks at what would happen to the UK economy if GNSS were unavailable for five days. Five days is, indeed, a long time. One hopes that a fix could be obtained in less than that amount of time. But one never knows, does one?

“The economic impact to the UK of a five-day disruption to GNSS has been estimated at £5.2bn.” Thus the per diem figure above.

The report was commissioned by Innovate UK, the UK Space Agency and the Royal Institute of Navigation. It followed from the January 2016 accident referenced earlier, in which an error in the GPS signal from certain satellites, triggered by the decommissioning of one of those satellites, brought a number of key industrial servers to their knees. The episode lasted 12 hours.

This report hypothesizes a more fleshed-out disaster and estimates the likely impact of a disruption to GNSS availability for up to five days across ten application domains in the UK: Road, Rail, Aviation, Maritime, Food, Emergency and Justice Services, Surveying, Location-Based Services (LBS), Other Infrastructure, and Other Applications.

The report is worth reading, not only for its figures, methodology, and discussion of mitigation, but also for two salient pages: “A day in the UK with GNSS” and “A day in the UK without GNSS.” At home, on the move, with others, at work, at the shops, when things go wrong, back at home. A post-modern (or post-Beatles) “Day in the Life.”

Even if the hypothetical disruption were not to last 5 days, but a much shorter period, perusing the two chronologies of with and without can serve to remind us how many of our daily activities are keyed to and thus dependent on GPS/GNSS.

Having no viable, working back-up — not even on the visible horizon — to such an essential system makes sense how?

About the Author:


Alan Cameron is the former editor-at-large of GPS World magazine.

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