Repeating the myth that Trident is GPS...
...it uses inertial guidance and starsighting.
Nowt to do with satellites from any country.
The European Commission has announced contracts for the procurement of the first 14 operational Galileo navigation-and-timing satellites. The Galileo service is now expected to begin offering some service as of "early 2014". However the date for full, reliable global coverage - which would require a minimum of 24 operating …
...it uses inertial guidance and starsighting.
Nowt to do with satellites from any country.
....that use a spotty youth with a 1989 AA road atlas. Or failing that, a lump of concrete. With the UK education system as it is, which of these options is more accurate is a matter of debate.
I thought that the GPS system parameters were intentionally chosen so that they couldn't be used by missiles, to avoid the embarassment of Russia dropping a megaton or two on the White House lawn with the help of US navigation aids?
Intelligence agencies would quickly figure out that ICBMs had been primed with GPS chips. Would be the quickest defence system.
"Russian launch detected. Quick! Switch off GPS for a couple of minutes!"
Mind you, I don't think ICBMs have the option of slowing down for a bit to try and hasten the "determining GPS location... please wait..." like we do with TomToms.
The reason the West could blow up Taliban by the hundreds from high-flying B-52 is the use of JDAM: Dumb bombs with fins attached to a GPS-enabled targeting widget.
"Thus far the taxpayers doing the most paying will be British, Dutch and German ones."
"It's to be expected that French nuclear-missile forces will be among the government agencies keen to use this."
You're just begging for a Daily Mail-esque tirade about the EU taxing us to death so the bloody frogs can have subsidised nukes and farms. You are Richard Littlejohn and I claim my €5.
They actually get some things right.. Any idiot looking at the numbers knows what the deal is with the French and paying for stuff (or lack of).
>>"They actually get some things right."
Well, whoopee do!
Surely the point is that they're supposed to get pretty much everything right - that's what should distinguish journalism from bigoted ranting down the pub.
If one has to check elsewhere to have any confidence at all in what they claim is wrong with Europe this time, people looking for information (rather than prejudice fuel) will just go elsewhere in the first place.
I though the 10m "innaccuracy" in GPS was deliberate dithering to make the commercial service less useful to terrorists, and the military version was as good as 1m too? This raises the question that if the 1m accuracy of Galileo is the only selling point then the US can match it just by removing the dithering, without havng to launch any new sats.
The 10m inaccuracy of GPS is standard. The deliberate dithering varied to +-100m which was the civilian service. This was switched off under the Clinton administration. The inaccuracies come from random delays of the signal through the atmosphere.
However, accuracy can be further enhanced by using information obtained through other means. For example, a TomTom pretty much assumes you will be on a road. A boat sat nav will assume you are at sea-level. You can also use Kalmann filters when moving. The more satelites you can see will also help.
As for strapping a GPS onto an ICBM, you can't without licencing the tech through the Pentagon/whoever. Standard GPS receivers don't work above 60,000 feet or at speeds greater than 1,000 knots - pretty much where you'd expect an ICBM to operate.
"I though the 10m "innaccuracy" in GPS was deliberate dithering to make the commercial service less useful to terrorists, and the military version was as good as 1m too?"
No, the original "selective availabilty" noise errors intruduced reduced the commercial accuracy to about 100m. It was switched off under presidential orders some time ago, and aparantly cannot be switched on with the new sats to be launched.
The accuracy of 10m requires you to see at least 1 more sat than the theory needs, to average out errors, and in open country can be achived. In city it's often impossible to see enough birds to even get a lock.
The Galileo system uses higher accuracy clocks, and a higher data rate amongst other things to give better ground accuracy, faster initial lock and more robust following.
Both systems can be augmented by ground based receivers at a preciesely known location that calculate the errors inherent in the system and transmit correction-factors to subscribing users.
GPS these days is better than 10M, especially with WAAS/EGNOS. It used to be a lot worse when Selective Availability was enabled but this was turned off years and years ago.
The Military version is still much more accurate though but only suitably-equipped military gear can read it (uses a different, much longer PRC IIRC).
> Standard GPS receivers don't work above 60,000 feet or at speeds greater than 1,000 knots
Almost right, but a common error.
The rule is that standard GPS receivers shouldn't work above 60,000 feet *AND* at speeds greater than 1,000 knots. Unfortunately many commercial GPS receivers do implement OR and not AND, which thoroughly hoses amateur balloon experiments that pass the height limit, but are drifting at wind speed.
Of course, there's no reason that 'enemy states' should adhere to the rules, which is why (IIRC) the GPS parameters were chosen so that the calculations failed if the receiver was moving very fast (> Mach 2?).
Its not just the ability to 'see' enough sats, but also your ground (handheld) gps system has to have a good receiver, clock, etc ...
Your phone... isn't accurate. Take a Garmin. Better hardware, more accurate.
You want really good accuracy, you'll need to set up a base station and let it run for 48 hours. Then you can achieve accuracy of within 3 cm. (This is survey grade equipment.)
[Accuracy will fluctuate during the day too.]
But don't worry. Your GPS map is only accurate to ~1.5 meters. (Not that you'd notice....)
I know I burned 1000 calories while sitting at a table eating lunch. Just ask my pedometer on my smart phone! :-)
"An intercontinental nuclear missile warhead forced to rely on its own inertial navigation and star sights is noticeably less accurate than one which can call on a modern sat-nav service. Such a warhead can still hit close enough to its target coordinates to eliminate a city, but not a hardened target like an underground bunker or missile silo"
Yeah, 'cause hitting with a fscking Intercontinental Nuclear Missile at +- 1 Km distance would make a huge difference huh?
You pretty much have to hit a hardened shelter spot-on to do much damage. That's why they're called "hardened" - they're specifically designed and built to take the hit. You fail at physics.
HAS s ain't that hard a 600lb will take one out with direct hit. They can take knocks from convetional weapons but a nuclear blast of significant megaton yield - all bets are off. Anyway the runway is now fried and all the comms are gone so not really significant.
Hardened shelters are specifically designed to take overpressure from nearby (as in, a few hundred metres) nuclear explosions, not to resist conventional PGMs. Just like you can puncture a tyre with a nail, you can stick a hardened bomb through a nuke-resistant bunker. But I seriously doubt a 600lb bomb would be the weapon of choice, more like 1000lb or above.
ps. You're not going to get into the megaton range from a nuclear blast, you twit. That sort of yield is for thermonuclear only.
Erm, did you actually read the article or the page you linked to?
"Specifications * Guidance system: inertial, with Star-Sighting, GPS
CEP: 90-120 m (300-400 ft) (with GPS guidance), ~120 m without GPS using the Mark 5 RV"
"An intercontinental nuclear missile warhead forced to rely on its own inertial navigation and star sights is noticeably less accurate than one which can call on a modern sat-nav service."
So, they can use GPS but don't have to.
One would assume they would use GPS in preference to inertial nav is more accurate provided a pre- emptive strike was not made first against those GSP satellites then star / inertia nav backup would come into play.
"It's to be expected that French nuclear-missile forces will be among the government agencies keen to use this"
Thought Galileo was supposed to only cover Europe? Did I miss some major league mission creep somewhere..
As for us and the yanks, we have access to their military codes anyway, regardless of who builds the weaponry.
The issue is more the risk of what happens if we want to nuke somebody and the yanks decide they don't like them, they can shut us down - which with the likes of Obama in the Whitehouse could be very iffy.
A global positioning system that only covered Europe, that'd be useful...
It's rather hard to build a satellite network that will only respond to signals from a single, rather squiggly-edged continent. I mean, they orbit the planet, why *wouldn't* it be a global system?
... paid by the taxpayer I hope they jolly well revise their commercial models swiftly so the taxpayer can benefit for free gps info.
Which is AFAIK the core function of this programme.
Note. It's a *satellite* system. They orbit the whole globe. It's simpler to put the signals out throughout the whole orbit which, with enough coverage gives the whole planet. This can be tweaked using a Molniya orbit to focus on a particular area of the planet (as used by Russia for high lattitude comms).
I'll be curious to see what effect the takeover of SSTL by EADS will do on their satellite pricing.
But 4 *years* to get them launched?
I have a friend who was doing some UK surveying work using GPS with "sub-centimetre" accuracy more than ten years ago, using the simple solution of having a real-time offset from a "known-good" location which was reading the same GPS signal and providing correction values to the in-field receiver.
If I recall it right, their known-good location was on the Portland lighthouse.
That's called Differential GPS (DGPS), the "differential" bit being that you stick a receiver on top of a point with precisely known coordinates, then it works out the difference between the calculated (i.e., "known") position and the observed position. Because the errors involved are roughly the same over a relatively large area, those differences can be applied at a remote location thus yielding better accuracy and precision. You can do this post-processing, or real-time (for which you need a communications link between the two receivers, typically a VHF radio).
The disadvantage of the above is that you need two receivers and a point with known coordinates (a geodetic vertex) in the relative vicinity. At the best of times it really messes up your logistics, and at the worst you are in the middle of a desert or ocean, thus lacking any form of nearby geodetic control.
Which is why some clever folk eventually came up with a couple of different approaches to either calculate and broadcast corrections over a wider area, or work out a set of corrections which work globally (known as a space state solution). Because a VHF radio is no longer quite adequate in these circumstances, those corrections are broadcast via various (geostationary) communications satellites, and are subscription based.
So as a professional user with certain minimum requirements in terms of precision, availability, etc., you currently either have the choice of going for the do-it-yourself-y approach first described (DGPS, RTK), or pay a subscription for one of the augmentation services (Omnistar, Starfix, Starfire, ...) Both cost a significant amount of money (so there goes the myth that GPS is "free": it's only so for recreational or very basic uses). What Galileo proposes in a way is integrating the different agumentation services into the system itself, thus reducing ancillary costs.
Incidentally, the newer survey-grade Trimble receivers come with 64 channels, meaning they can track up to 64 sats at the same time although at the present moment there are only about 50 operational sats in total up there (~30 NAVSTAR + ~20 GLONASS + a handful of more or less experimental stuff from the Chinese, Japanese, and Europeanese), of which typically only 10-15 are visible simultaneously at any given time.
Not entirely sure what my point was to start with, but there you go.
For nukes ? Surely the same postcode does the trick...
"HAS s ain't that hard a 600lb will take one out with direct hit. They can take knocks from convetional weapons but a nuclear blast of significant megaton yield - all bets are off. "
True but with the increasing accuracy of US warheads the yield has been dropping quite a bit. IIRC the Titan was the last Mt class warehead. The tridents carry something like 10-15 in the 10-100Kt class. More, smaller but more accurate. this also means you'd need to comit more of them for that size of target.
I've sometimes wondered why they don't build battlefield nuclear missiles by taking an ICBM warhead, wrapping it in nose cone and putting it on a re-furbed lance or pershing. However the arms reduction talks have made this redundant.
OK, maybe I'm just aspirational, but why not make this the first GLOBAL service.
The United Nations could take ownership of the "GPS" service, with all countries contributing to the up-keep and development.
I totally understand the military won't want to do this, but for the other 192 sensible governments in the world it must make economic sense
Biting the hand that feeds IT © 1998–2017