17:42 Tuesday 8th March 2011
Drivetime BBC Radio Cambridgeshire
ANDY BURROWS: Satellite navigation is everywhere now, isn’t it? Many drivers rely on it, if you’ve got a sat-nav in the car. Big business relies on it as well. It’s used by financial companies, shipping and air transport firms, and by the emergency services. But are we too reliant on it? The Royal Academy of Engineering is publishing a report on the GPS system, assessing what would happen if it failed. Well earlier I spoke to one of the report’s authors, Dr Martin Thomas, and asked him to explain, first of all, how the system works. (TAPE)
DR THOMAS: There’s a network of 31 satellites in the GPS cluster, 24 of which are actually being used at any one time. And they provide a very accurate time signal. And that means that if you know exactly where the satellites are, and you know at what time that signal arrives at your receiver, you can do some clever geometry, and work out exactly where you are. And that essentially is how GPS works, by broadcasting these time signals.
ANDY BURROWS: So it’s everywhere at the moment. Is it the same stuff that we use in our car?
DR THOMAS: Yes. Absolutely. It’s the same signal that’s used in a sat-nav. But it’s also used for an absolutely enormous range of applications, on the railways, in ships, in planes. Telecommunications networks use the timing signal. Electricity transmission networks use the timing signal. It’s everywhere.
ANDY BURROWS: And the fear is that we’re just too reliant on it?
DR THOMAS: Yes. The concern of the Royal Academy of Engineering is that we’re increasingly building applications that depend on the GPS signal, either directly, or because they’re dependent on another service that depends on the GPS signal, and that we’re not always aware that we’re dependent on that signal. So we’ve got a lot of systems, an increasing number, which could all fail at the same time.
ANDY BURROWS: And what would happen?
DR THOMAS: Well, if everything cut off, we’d probably muddle through. There would be trouble, and it would cause quite an economic impact. Something like 6% of gross domestic product across Europe is dependent on GPS, one way or another.
ANDY BURROWS: Good grief! In what way? We’re talking more than just deliveries, I suppose?
DR THOMAS: Well yes. But it is deliveries. It’s things like large scale agriculture. These days, a modern farm maps out its fields in great detail, works out the needs of the soil, metre by metre, and only puts on the fertiliser metre by metre, that is actually required for that particular square metre of soil. So there’s a lot of agricultural machinery now which is dependent on GPS for doing very detailed mapping of fields, just as one example.
ANDY BURROWS: So is anyone listening to your plea then, do you think? Is anyone saying, well, hang on, they’ve got a point, the Royal Academy of Engineering here. We must do something about this.
DR THOMAS: Yes. We’ve had conversations with the Cabinet Office in the UK, and with the Centre for the Protection of National Infrastructure. And they are increasingly aware of these issues, and are clearly working on it. Indeed, there’s a conference on Thursday, down at the National Physical Laboratory, which is looking into the ways in which we can detect incidents of people jamming the signal, either deliberately or accidentally, and warn people about it. And also looking into ways in which we can make the whole system more resiliant.
ANDY BURROWS: And do you use it Doctor? Have you got one in the car?
DR THOMAS: A sat-nav? No I don’t. I travel by train mostly.
ANDY BURROWS: (LAUGHS) Dr Martin Thomas, that was, from the Royal Academy of Engineering.
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