(Thread title changed for clarity.)
TANSTAAFL..
Or, to state it fully, There Ain't No Such Thing As A Free Lunch..
My daughter bought herself a NavMan GPS system for Christmas, and is as pleased as punch with it - it gave her the confidence to drive for the first time from Petersfield to wildest Essex..!
However,(and this is where the story really starts..) has anyone else wondered when the American satellite operators/financiers are going to announce that starting in (say)12 months, they're scrambling the signals and if you want to use your system it'll cost you £xxx per year..It must have cost billions to set up, and we've had 15 years use free of charge - now call me a cynical old Victor Meldrew, but altruism isn't the first word that springs to mind when thinking of American 'big business'.
Does anyone know if this is already being addressed by means of a licence fee payable by the manufacturers?
Also, I hear today that Europe is launching its own satellite array,-'Galileo',in order that all the security/banking/aviation etc. systems could be operated if the current system was terminated for any reason.
Any thoughts on this?
Happy New Year to all Backroomers -
P.
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The American GPS system is run by the US military, and so it's unlikely to be scrambled at any time. The only time it'll get switched off is if there's a major war and they don't want the signals being used by the wrong people (i.e. anyone else outside the continental USA).
Andy
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Funnily enough, Europes first GPS satellite was launched today from Khazakstan.
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It wont be scrambled, it wont be switched off, it wont be chargeable. As it is now is as it wil be in the future.
The Yanks have moved on to to something super accurate and unjamable
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TourVanMan TM < Ex RF >
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As the Captain of a dynamically positioned ship the US GPS system is the primary means of keeping my vessel in position, and I am very familiar with it. However as Andy P states this is a military network and it is detuned for civilian use in order (presumably) for the military to keep the edge over any potential misusers.
This means that for the required accuracy we must subscribe to a DGPS (differential GPS) system which uses additional land based transmissions and give an accuracy of about 1 metre.
Once Galileo is up and running most European shipping companies will probably make the change eventually, but I would imagine new receivers will be necessary - same goes for car satnav systems.
So long as this doesn't get detuned the saving in subscription costs should soon cover the costs of the new equipment and we will not be at the mercy of the US in the event of a global emergency.
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So what, all they have done is launced the first of 31 satelites. How long do you think it'll take to get the other 30 airborne, not likely to happen in the next 5 years i think. From using GPS in Aircraft you need a minimum of 3 satelites to track to give latlong and altitude, would have thought car satnav needs only 2 as altitude is not required.
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2013 according to the Today programme.
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you wont get altitude from three sat locks me old fruit.
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TourVanMan TM < Ex RF >
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Do a/c use the GPS altitude?. Barometric altimeters may be innacurate but at least set to 1013 they're all equally innuccurate!!
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"GPS altitude"
I have Memory Map on my Navman and altitude readings are notoriously inaccurate (and not even consistently inaccurate ie, it's random inaccuracy). I think I read that this is deliberately so - but I can't remember why, maybe to do with certain organisations needing not only locations but also altitudes in order for them to guide missiles accurately? Therefore the "missing" altitudes prevented Scuds from being guided accurately? Also means that you don't know how far up Snowdon you are!
By the way, I've been receiving weather satellite pictures from NOAA satelleites for about 20 years and they have been threatening for about the same time to make these "payable". Hasn't happened yet, so unlikely that GPS will be "pay for" in the short, or medium or even long term
Phil
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Most modern systems are already WAAS enabled.
Car satnav needs four sats minimum.
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"There Ain't No Such Thing As A Free Lunch.."
Well actually there is, but thats another topic for another day.
GPS isn't free it was paid for by the US tax payer.
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if you want more accurate than ordinary satnav you can buy another service whos name escapes me for the minute but it is accurate to less than 10 cm
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GPS height / altitude can be accurate down to 1cm if necessary. We use GPS to measure subsidence where I work which is an oil production platform fixed to the sea bed in the North Sea. The set up does need a specialist choke ring antenna, and as far as I know needs to be in place over several hours before such accuracy can be obtained. The system just sits there 24/7 and does it's thing reporting data back to shore somewhere.
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1. Aircraft determine their altitude either by air pressure or radar.
2. The most accurate positioning system is DGPS - Differential GPS. This uses land-based radio transmitters to supplement the satellites. Normal GPS has an accuracy of around 10m. DGPS can reduce this to 1 to 5 metres. WAAS and LAAS are even more accurate.
More info ar www.gpsinformation.org/dale/dgps.htm
Andy
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I imagine the future will lie largely with land based systems such as the 3G/GSM networks, at least the operators of these systems seem to think so as so many devices will already contain their receivers already. Location based services is their new buzzword.
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Except that 3G phones with location facility do this using GPS technology.
The service content is just a method of increasing customer spend.
--
I read often, only post occasionally
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> Except that 3G phones with location facility do this using GPS technology
GPS in a phone on its own is fine out on the open road, but most consumers spend most of their time using premium services on foot/taxi/train in the so-called urban canyon. In streets surrounded by high structures the system will take time to get an accurate (3+ sat) fix. Way forward is Assisted GPS (AGPS) which prompts the fix process by using cell site info. A Cambridge company called CPS developed a very accurate system using distance from cell sites calcs developed from astro-research - expensive, but much more accurate in the urban canyon than straight GPS. They are now partnering with GPS-plays to get around the UC problem.
LBS has been much touted for years - never delivered to date, but perhaps 3G will help it. Still not sure about it though. I've been quite heavily involved in it for the last five years.
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