[Dude111]

GPS was originally developed for the military.

24 satellites positioned around the Earth in order to give soldiers a precise location at any given time. These signals were encrypted and still are. (I think)

But its interesting to know there are a number of companies building and selling GPS devices openly.

They have become as common as a wrist watch and more than likely you can get a GPS built into a wrist watch.

The courts in Canada @ one point said it was illegal for example to receive programming from US providers on the basis that it is illegal to decrypt encrypted signals. If this is the case,isnt every one who owns or manufactures GPS devices criminals?

[KoolKid]

The GPS system was opened up and made freely available to all AFAIK.

[listermint]

Its been open for yonks, they changed the accuracy for commercial providers to make it more accurate.

Im surprised one did not research this yet,

[shizz]

Originally Posted by listermint

Its been open for yonks, they changed the accuracy for commercial providers to make it more accurate.

Im surprised one did not research this yet,

Did they not make it less accurate? It is the US military after all, they'd like to be more accurate than the common Joe.

[Alun]

Originally Posted by shizz

Did they not make it less accurate? It is the US military after all, they'd like to be more accurate than the common Joe.

When GPS was first launched the unencrypted signal available to regular consumers was artificially made less accurate by adding errors to the signal, called SA, or Selective Availability. Bill Clinton turned it off at the start of 2000 and it's been off ever since. The US military have access to encrypted and more robust signals that are less prone to jamming, but I don't know any details about the accuracy side of things (and if I did I'd have to shoot you!)

[robinph]

Originally Posted by Dude111

They have become as common as a wrist watch and more than likely you can get a GPS built into a wrist watch.

You certainly can, have a couple of them myself:
http://www.itechnews.net/wp-content/...ss-devices.jpg

There are a couple of alternative systems that don't rely on the US military liking the rest of the wold so keeping the encryption turned off:
http://en.wikipedia.org/wiki/GLONASS
http://en.wikipedia.org/wiki/Galileo...te_navigation)

Although the Galileo system isn't operational yet, there are GPS devices that will work with both GPS and GLONASS already on the market:

https://buy.garmin.com/shop/shop.do?cID=145&pID=87774

[coylemj]

UK defence firm BAE Systems has come up with a positioning system that it says "could make GPS obsolete".

It's called Navigation via Signals of Opportunity (Navsop) and uses the different signals that populate the airwaves -- including Wi-Fi, TV and mobile phone signals -- to calculate the user's location, down to within a few metres.

GPS uses a specific satellite signal to determine where a device is, globally. It can be jammed and spoofed, isn't very helpful indoors, and is often imprecise.

http://www.wired.co.uk/news/archive/2012-06/29/bae-gps

[gbee]

iPhone and others already use [NAVSOP] nav with systems of opportunity, they will read sats as well as locate via cell towers and WiFi so they often work underground and buildings where 'pure' GPS won't.

[Tabnabs]

Originally Posted by Alun

When GPS was first launched the unencrypted signal available to regular consumers was artificially made less accurate by adding errors to the signal, called SA, or Selective Availability. Bill Clinton turned it off at the start of 2000 and it's been off ever since. The US military have access to encrypted and more robust signals that are less prone to jamming, but I don't know any details about the accuracy side of things (and if I did I'd have to shoot you!)

DGPS made a mockery of SA eventually as did the prolific use of civilian gps by US (and allied) military personnel. A good article about it here http://en.wikipedia.org/wiki/Differential_GPS