GPS Doomsday? Not Yet But…

 AIS, ECDIS, navigation  Comments Off on GPS Doomsday? Not Yet But…
Mar 092011

The Soyuz-Fregat launch vehicle carrying GIOVE-B on launch pad, 2008 Photo: ESA - S. Corvaja 2008

That is how New Scientist described the results of a GPS jammer during tests off the UK coast. Although illegal in many jurisdictions, the devices are available online for as little as $30. While these results are dramatic, as a report from the Royal Academy of Engineering published this week shows, some GPS vulnerabilities may be more subtle and growing dependence on GPS needs to be moderated by greater awareness of threats to the system’s integrity.

The academy’s study has identified an increasing number of applications where position-navigation-timing, PNT, signals from global navigation satellite systems,  GNSS, are used with little, or no, non-GNSS based back-ups available. The trend is for GNSS to be used in a growing number of safety of life critical systems. Unfortunately, the integrity of GNSS is insufficient for these applications without augmentation. Non-GNSS based back-ups are often absent, inadequately exercised or inadequately maintained.
The original implementation of GNSS, the US operated GPS comprises ground based, space based and receiver segments, all of which are susceptible to failures of various types. There are also some common mode failure mechanisms which can affect whole classes of receiver or even the entire satellite constellation.
A failure, or loss of signal due to some outside influence, can result in a range of consequences depending on the application; in a telecommunications network, a small loss in the efficiency of data handling may occur while the system ‘freewheels’ until a signal is restored: in a surveying application where timing is not critical, some delays may occur before the survey can be properly completed. In such applications, a temporary loss of GNSS signals might be considered an

inconvenience. However, where systems are used in safety of life critical
applications, the consequences can be more severe – in some situations, even if operators are well versed in procedures for a loss of GNSS signals, the number of interlinked systems simultaneously activating alarms can lead to eroded situational awareness of operators in what could well be an emergency situation.

GNSS have system-level vulnerabilities: GPS satellites have on rare occasion broadcast dangerously incorrect signals, a reduced number of satellites visible could prevent availability of a position fix, and GNSS receivers can incorrectly process valid signals to give unpredictable results.
GNSS signals are very weak: typically less than100 watts transmitted from a
distance of 20,000 km to 25,000 km. When received at the surface of the earth, the signal strength may be as low as –160 dBW (1 x 10–16 ) watts, with a spectrum spread out effectively below the noise floor in the receivers. Deliberate or unintentional interference with this signal can easily defeat the signal recovery or overload the receiver circuitry.

Furthermore, signals are vulnerable to disruptions in the atmospheric medium they pass through, and receivers can also unintentionally lock onto reflections of the signals, known as multipath, giving unexpectedly large errors.
These causes can have quite different effects on users, such as partial or complete loss of the positioning and timing service, poorer accuracy, very large jumps in position, velocity or time, and ‘hazardously misleading information’ (HMI) that is to say, believable data that is dangerously wrong in safety critical applications.

Report from the Royal Academy of Engineering.

New Scientist Article: GPS chaos: How a $30 box can jam your life


See Also:

The Sun Has Got His Spat On…

GPS: Do You Need To Fix Those Fixes?

Sat Maintenance May Degrade GPS Performance

GPS Hacking May Sink Ships

Where’s the GPS Gone?

GPS Losing Its Way?

Zombie GPS

Nautical Institute launches ECDIS and Positioning,

 ECDIS, ECDIS, maritime safety, navigation, publications  Comments Off on Nautical Institute launches ECDIS and Positioning,
Mar 292010

Dr Andy Norris

The Nautical Institute has launched ECDIS and Positioning, by Dr Andy Norris CNI to provide mariners a grounding in all aspects of ECDIS and the use of electronic charts.

ECDIS and Positioning, the second volume of Dr Norris’s Integrated Bridge Systems series, helps paper chart-taught officers to make ECDIS work for them. It also helps new entrants to the industry, who may be more familiar with Google Earth, to understand how to use the system within accepted navigational principles.

Institute President Captain Richard Coates FNI expressed concern about the “inadequacy” of ECDIS training. “Despite the long use of satellite systems for positioning and the imminent mandating of electronic charts in 2012, there is little information written for the mariner concerning the practical use of these technologies,” he said. “Many are grappling with the problems of using electronic charts and ECDIS after being trained on paper charts.”

ECDIS and Positioning by Dr Andy Norris CNI, ISBN: 978 1 906915 11 7, price £40, is available from The Nautical Institute

Hydrographic Survey for Straits of Malacca and Singapore Underway

 charts, ECDIS, ENC, navigation, news  Comments Off on Hydrographic Survey for Straits of Malacca and Singapore Underway
Mar 102010

image A key hydrographic survey within the Traffic Separation Scheme, TSS, of the Straits of Malacca and Singapore is now underway, as part of the Marine Electronic Highway Demonstration Project, a regional project that IMO is carrying out for the Global Environment Facility World Bank. The purpose is to produce an updated electronic navigation chart of the area.

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GPS Hacking May Sink Ships

 AIS, ECDIS, navigation, news  Comments Off on GPS Hacking May Sink Ships
Feb 232010

22km difference - results of a jammed GPS

On the left is a picture from an experiment carried out in 2008 by Alan Grant of the UK’s General Lighthouse Authorities. A vessel’s GPS receiver is reporting its position 22km away from its true position because it has been jammed by a device almost anyone can buy off the internet.

The question is probably not will a major incident involve a GPS jammed vessel but when. It highlights the need for seafarers to be familiar with, and competent in, traditional methods of navigation.

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The Sun Has Got His Spat On…

 ECDIS, maritime safety, navigation, news  Comments Off on The Sun Has Got His Spat On…
Feb 122010

NASA's SDO ready for launch

And coming out to play with your satellite navigation, and possibly satcoms, too, so the launch of the Solar Dynamics Observatory scheduled for today is timely.

After years of such quiescence since the Sun’s last maximum activity in 1985 that some astronomers muttered about a new Maunder Minimum*, the sun has suddenly woken up. Within the next few years we’ll be licked by solar flares and a variety of phenomenae that will reach out and touch the constellations of satellites on which we now depend and nobody really knows what’s going to happen.

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The Electronic Navigators

 AIS, ECDIS, ECDIS, ENC, navigation, parallel index, VTS  Comments Off on The Electronic Navigators
Feb 042010

Captain S. Pullat

Electronic navigation isn’t the future, it’s now, but are today’s navigators too complacent and trusting? Is eNav a threat to good seamanship?

MAC contributor Captain S Pullat sends up some signals.

What paradigm shifts through couple of generations from total visual navigation to complete electronics dependence! Ask practitioners and what is surmised is that Radar, VHF, ARPA, AIS, Integrated Bridge, VTS and the rest put together has precipitated so, COSCO BUSAN a sad example.

From the days of single locked Radar to S-mode for safe-n-quick user friendly switching, the navigators have come a long way! And given the 25yr or so lifespan of ships with grandfather leniencies, one can be sure that all and sundry systems and practices sail side by side; the navigators on contract switching between such diverse technologies.

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UKHO Launches The Future

 Admiralty, ECDIS, ENC, navigation, passage plan, UKHO  Comments Off on UKHO Launches The Future
Dec 072009

imageIt’s the “future of navigation” said the United Kingdom Hydrographic Office as it launched Admiralty e-Navigator in Singapore recently. Admiralty e-Navigator is the UKHO’s new integrated digital catalogue, product viewer and passage planning tool which makes every stage of navigation and fleet management smarter, simpler and safer – at least, so says the official press release.

Admiralty e-Navigator organises, updates, and brings together all of the paper and digital information needed to plan safe voyages and simplify essential tasks. Whether on the bridge or in the office, e-Navigator will not only give access to a wealth of information, it will organise, maintain, and display all of that data, so bridge and office-based teams have instant access to all the navigational information they need, whenever they need it and wherever they are in the world.

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