Page 12: of Maritime Reporter Magazine (November 2020)

Government Update

GPS Unreliability he Global Positioning System (GPS) has come more widespread. While military-grade GPS receivers become vital to the maritime community. would probably be minimally impacted, commercially avail-

Proper use of properly functioning equip- able receivers would be vulnerable.

ment can allow ships to safely navigate The GPS service is provided by the United States govern-

T worldwide. It’s signals are now integrated ment, which can selectively deny access to the system, as into a variety of shipboard items, including happened to the Indian military in 1999 during the Kargil the automatic identi? cation system (AIS) con? ict between India and Pakistan in the Kashmir region, or and the electronic chart display and information system (EC- degrade the service at any time. Periodically, the GPS signals

DIS). It has been copied by Russia’s GLONASS, Europe’s in selected areas are degraded for a short time, but advance

GALILEO, China’s BeiDou, India’s IRNSS, and Japan’s notice is provided.

QZSS. The most serious problem, as mentioned above, is that the

Originally developed for the US Navy for ship position- satellite signals are relatively weak. This enables both jam- ing and navigation, GPS’s very precise timing has proven ming and spoo? ng. Jamming, either by a malicious actor or invaluable to modern electronic commerce. Bank transfers by someone seeking to hide their own activities, is a continu- and credit card transactions would be greatly hobbled if the ing problem, Short-range jamming transmitters, although system shut down. From a pure economic perspective, the illegal, are easily obtained and used. More powerful and

GPS timing function is of more importance than its position- longer-range jamming capabilities have been mostly limited ing and navigation functions. to state actors, at least to date.

Like all radio-based services, GPS is subject to interfer- Spoo? ng involves sending signals on the GPS spectrum to ence from both natural and human-made sources. A GPS unit one or several receivers with false information. It has been can lose reception in the presence of devices designed for demonstrated that a ship can be tricked into following a bo- intentional radio jamming. Solar ? ares can also disrupt GPS gus track-line if it relies solely on output of its GPS receiver. equipment. For this reason, the US government strongly en- So many vessels have placed excessive reliance on GPS and courages all GPS users to maintain backup/alternative posi- electronic navigation that this presents a real danger. This is tioning, navigation, and timing capabilities. In addition, the particularly true since the technology to spoof GPS signals is government is currently ? elding new GPS signals that are not that dif? cult to obtain.

more resistant to interference. All of this highlights the need for a backup system that

Regardless of these improvements, the major vulnerability can stand in for GPS when the GPS signal is unavailable or is the low power of the signals from the satellites. Land- unreliable. E-Loran is one such alternative. It was under based radio navigation systems, such as LORAN-C, broad- development by the US Coast Guard until funding was un- cast with greater power and are signi? cantly more dif? cult to explainedly cut. Other nations have run E-Loran trials, but jam. These land-based systems were also not vulnerable to no overall program has been developed. Other alternatives solar ? ares and presented greater resistance to electro-mag- have been considered on a theoretical basis. Only the United netic weapons. LORAN-C (now retired from service) was States has the technology and leadership capability to effec- not as accurate at GPS, but new land-based systems under tively tackle this problem. Something must be done soon, development have the capability to rival GPS accuracy with- before the entire positioning, navigation, and timing system out GPS vulnerabilities. on which the modern world relies becomes further unreliable.

It is of? cial policy to the United States Government to fully Failure or unavailability of GPS without a reliable alternative develop and implement an accurate back-up system for GPS, is a super-high consequence problem, with probable costs in but funding and urgency for such action has lagged. the trillions. Continued dithering is not an option.

The US government regularly reports on GPS interference

The Author in locations like the Black Sea, the eastern Mediterranean, and waters off China. These incidents of interference are

Bryant suspected to have been caused by the Russian and Chinese

Dennis L. Bryant is with Bryant’s governments, probably as tests and demonstrations of their

Maritime Consulting, a regular capabilities. If international tensions were to rise dramati- contributor to Maritime Reporter & cally, it should be assumed that GPS interference would be-

Engineering News. 12 Maritime Reporter & Engineering News • November 2020

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