GNSS AND LORAN – C
In the California harbour shown in Figure 2, a couple of cheap television antenna units on boats developed faults which caused them to radiate signals that jammed GPS. On every vessel in the harbour, and for a kilometer out to sea, GPS either stopped working or give wrong positions. It took months to track down this completely accidental interference. GNSS jamming is rather like computer viruses, and indeed jammers are there on the web. It doesn’t take Al-Qaeda to block GPS over a city, even an individual with sufficient eagerness can do it! GPS is currently as vulnerable as were the computers before the first virus was found.  Figure 2. Two faulty tv antenna amplifiers ina vertently jammed GPS for months in this Califonia harbour (Picture: Clynch et al, ‘Multiple GPS RFI Sources in a Small California Harbor’, ION GPSO2, Portland OR, 2002) It has taken the proportion of a problem and Europe’s response to it has been interesting. Many nations, such as the United Kingdom, have responded to this problem nationally. The position of UK is that they require multiple navigation systems for marine navigation and aviation. That is, they focus their response on traditional navigation applications. These are indeed safety-critical areas, and governments do have responsibilities for them. A great numbers of European governments are to yet recognize the critical role that GNSS now plays in our economies outside traditional navigation. They ignore the use of GPS for telecommunications timing, mobile phones and emergency calls. There will soon be millions of new GPS users, maybe 96% of the market, whose use of GPS they simply do not appear to regard as critical. They take the view that these users don’t really need satellite navigation; they could simply go back to using what they had been before! Is Galileo the Answer? And then there is the European myth that Galileo will be immune to the problems of GPS. The European Commission has stated that Galileo will be far less vulnerable than GPS, so eliminating most concerns raised in the Volpe report. How they have come to this conclusion that Galileo will be immune to GPS jamming is a mystery as it is known now that it will occupy the same frequency bands as GPS and that we will be using receivers in which GPS and Galileo share antennas, amplifiers, processors and power supplies. And even if Galileo were immune , there is no point in waiting for it. Galileo is still a concept. The whole navigation industry currently uses GPS. Europe is moving towards a European radio navigation plan. Helios technology was contracted by the European commission to prepare the ground. A recent Helios study confirmed that what Volpe had said is also true in Europe. Fewer than 40 of 137 GPS applications analyzed by Helios would keep running if GPS and its augmentations are lost. These applications included not only the obvious risks of coastal shipping, harbours, and the fishing industry, but also unexpected ones such as bank cash machines, mobile phones, the tracking of goods, the time-stamping of financial transactions and stock-market records, agriculture, insurance, science, and security. Many of these applications use GPS for precise timing rather than location. The Volpe Report The time to face the facts is now, and it has to be recognized that all satellite navigation users rely on navigation industry, that satellite navigation is now truly a public utility. Europe must do as the Volpe Report proposes: identify the threats and make plans to deal with GPS and Galileo vulnerability. It must do so on behalf of all users, not just navigation industry, but also the overwhelming majority of those who employ simple low-cost GPS receivers in their vehicles and mobile phones. They are the future of the satellite-navigation businesses. Clue may be taken from the US Department of Transportation which responded to Volpe report with a detailed study of the implication of loss of GPS for each mode of transport, and then formulated strategies. |