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Chicken Little report: Sat-nav dependency spells DISASTER!

Quango pushes 1940s tech as backup for GPS

The Power of One Infographic

How on earth did sailors ever manage without GPS and AIS*? We used to use this amazing thing called radar

Quite frankly in coastal situations it will not be eLORAN that saves a ship when GPS goes out – it will be radar and the Mark I eyeball, both essential anyway to avoid the large numbers of smaller vessels and other hazards which carry no AIS transponders and are not marked on charts. Radar will also keep you off the mud if you can navigate at all.

Nonetheless the RAE report's authors write:

At sea in fog or at night, jamming could cause collisions between ships or with obstructions ...

That's perilously close to being movie-plot stuff. We contacted Richard Ploszek at the RAE, who helped write the report, to see what he had to say.

"The emphasis is on could," he told the Reg. "We feel that safety margins are being eroded."

Radar and basic seamanship will get you in and out of harbour, too, in any visibility conditions short of freakish. Sure, plenty of ordinary longhaul bridge officers – and even some captains and/or specialist navigating officers, both merchant and naval – would struggle, especially in really thick fog, but they don't normally take their ships in and out of unfamiliar ports: expert local harbour pilots do, and they won't have any trouble without GPS.

Fully automated berthing (where you might not get the chance to call in a pilot if the system failed) calls for an extremely manoeuvrable ship, most likely fitted with bow thrusters and/or omnidirectional Voith-Schneider thruster propulsion. A captain who can't get something like that alongside the jetty safely without help from automated positioning, fog or no fog, shouldn't be in his job.

Far out at sea where you can't use radar to navigate, it takes long enough to get anywhere that you can simply run on dead-reckoning and wait for GPS to come back on – or get out your trusty sextant once the weather is clear enough as people used to do, and as all sea officers are still trained to do. Don't bother turning on the eLORAN, though, not far out at sea. It doesn't reach there.

As for non-maritime uses for eLORAN, it just isn't accurate enough - certainly not without loads of differential assistance stations all over the place, and not even then for metre-accuracy applications of the future. It might serve as a means of detecting a gross error in a satnav position, but in most cases you could do this much more easily using the local cell tower network as a cross-check. A large number of GPS-enabled devices already include mobile comms (or are mobile comms) and this will only increase. Basic cell location based on a single tower is inaccurate – often as inaccurate as LORAN, in fact – but you can do a lot better by triangulation using several cells rather than just one, and plenty of work has already been done in this field.

Still though, there is the matter of timing. Those local cell towers are often dependent on GPS time signals to stay in sync, remember.

Well, sort of. There is actually a government-supplied free backup time signal already: the "MSF" (nobody really knows what this stands for) radio station which has long been run by the National Physical Laboratory, now co-located with the new UK LORAN transmitter at Anthorn. So in fact nobody needs to be dependent on GPS for accurate radio time signals.

The RAE's Ploszek suggested to the Reg that the MSF signal isn't good enough to stand in for GPS, saying "at 60Hz, I'd suspect that it isn't going to offer enough precision".

But the GLAs - who would surely tell us if MSF is no good - write in The Case for eLORAN:

MSF is used by many industries to back up GPS as the primary means of timing. Users include telecommunications networks ... The need for the MSF will be reviewed in 2010, at which time a decision will be taken on its possible replacement by LORAN in 2017. There is a window of opportunity to have eLORAN take over the provision of timing signals from the MSF.

In any case, cutoff of timing signals is hardly an occasion to panic that the mobile data network or other important digital comms will come crashing down. The GLAs also admit that cell towers will keep on working for days before loss of timing signals will cause them to fail. Local jamming or interference would have to go on for days at a time before having any effect on comms. Certainly, as the GLAs say, "a long-term catastrophic loss of the core GPS constellation" would have severe effects, but not a total wipeout - if the GLAs are to be believed, at least some of our comms network can switch to MSF backup for timing.

Then, it seems quite plausible that soon enough highly accurate clocks will be easy to install, so largely removing the whole timing issue:

Chip Scale Atomic Clocks [CSAC] are just emerging from the R&D labs with first commercial deliveries recently announced ... This represents a clear paradigm shift in technological innovation and this is a technology to watch since it promises an ability to withstand outages for many months.

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