GPS Fix positions compromised

[Dave_Snelson]

I have had a problem with my Tom Tom for three weeks now and driving back along the M6 north, I lost satellite signals from Birmingham to Stoke. I have Tom Tom's help desk number on my phone, so I called them. Long story short, the US military is performaning maintenance functions (uplinked of course!) to all of the GPS satellites and the work should have been completed by now, but hasn't.

Clearly a Tom Tom in-car device doesnt have the antenna attraction of an outdoor marine navigation device, but nonetheless, you have been warned! There may be only 3 available sats at any one time, making nav by chart plotter inaccurate. Pass this on to any sailing chaps that may not log into MoBo. I won't post this on all forums coz I can't be bothered with the whinging flamers that will undoubtedly moan at me if I did.

 

[DAKA]

Check this out Dave

http://www.ofcom.org.uk/static/subscribe/gpsjamming.htm

US military will let you know when they mess with the system.

 

[Dave_Snelson]

Check this out Dave

http://www.ofcom.org.uk/static/subscribe/gpsjamming.htm

US military will let you know when they mess with the system.

That's useful - thanks!

 

[Medskipper]

As I understand it the american satalites are aging fast and are already older than they were designed for. The basic 24 sats have are up to 31 and still only half are in working order! It is said that the motorist will start to suffer long before any marine use because with a boat you are in a large area and only really need 3D to get a fix. The motorist does need more acurate info because there are so many more roads and turn offs to take into account. I have just returned from my boat in spain and I was logged onto at least ten satalites at any one time!

Barry

 

[rickp]

As I understand it the american satalites are aging fast and are already older than they were designed for. The basic 24 sats have are up to 31 and still only half are in working order!

The satellites have lasted far longer than anyone dared hope originally - so to say they're 'older than they were designed for' may be true, but gives the wrong impression.

However, to imply that the constellation is in someway degraded is completely wrong. Of the 48 satellites launched so far (ignoring the Block I 'development' satellites) - 1 failed to make orbit (IIR-1, launched on 17/1/97) and 16 are "no longer in service". That means they still have 31 operational, the earliest of which was launched on 26/11/90. 2 of the "no longer in service" satellites are kept as 'spares'.

The design of GPS requires 24 satellites for full operation - so they have more than enough at the moment. I can find no evidence that "only half are in working order" - perhaps you can provide a source? The US provide the information of the satellites here.