Chartplotters - another enthusiastic convert . . .

[rickp]

I'm rather suprised that our local doom-monger hasn't jumped on this report as yet more evidence the sky is falling in...

 

[Refueler]

Whilst it is true that the GPS system is a bit behind on launching some of the replacement satellites, and this will reduce the number of operational satellites over the next few years, some things to bear in mind are:
- the press releases that kicked this off are part of a fight for budget in the US, so paint worst case scenarios
- for general marine use it is not forecast to be a problem, at least for position fixing within the accuracy of the charts. High precision users such as surveyors are already noticing a reduced satellite coverage, and it will also be noticed by satnav users due to buildings obstructing skylines in urban areas
- in the longer term things will be back on track, the problem is just with the current batch of satellites being behind schedule and over budget from the manufacturers.

Of the other GNSS systems, the Russian Glonass has had large investments in it and is almost at fully operational status - this is scheduled for the end of this year, I believe. Surveyors etc have been using combined GPS/Glonass receivers for years. Galileo isn't going to be around until 2013 at the earliest, and although the Chinases are making fast progress with Compass their last satellite failed soon after launch. Hopwever in time we will get general marine GNSS receivers that will use all available satellites, especially as there is a common standard for signal structure (except for the older Glonass satellites, though the latest satellites will be dual operational, so GPS compatable).

The other thing that is coming soon is eLoran. This is basically Loran on steroids, giving 8-20m accuracy. In fact the NW Europe Loran chain is still in operational, if you have an old receiver anywhere, though only the UK transmitter has been upgradeed to eLoran as far as I know (moved from Rugby to the lake district). eLoran will also be proof against GPS jamming exercises by the military, and other sources of interference.

Regarding the ability to "steer" the GPS system, although theyt are not geostationary satellites this can be, and is, done. The orbits of the satellites are changed to give denser coverage over certain parts of the world. It is probably no surprise that this is presently concentrated over the middle east, due to the US invasions of Iraq and Afghanistan.

Also Glonass was 'refocussed' for Russian Ops in Chechnya ... which also delayed further work on the system.

 

[maxi77]

I'm rather suprised that our local doom-monger hasn't jumped on this report as yet more evidence the sky is falling in...

Perhaps because it also leads the moderately inquisitive to this which shows a pretty staedy investment in new sattelities over the past 10 years which makes the concept of GPS falling of the edge of a flat earth less likely.
http://www.gpsworld.com/gnss-system/almanac/the-almanac-4265

 

[rickp]

Perhaps because it also leads the moderately inquisitive to this which shows a pretty staedy investment in new sattelities over the past 10 years which makes the concept of GPS falling of the edge of a flat earth less likely.
http://www.gpsworld.com/gnss-system/almanac/the-almanac-4265

You and I (and Smartcom) know that, but it hasn't stopped the flurry of posts about the end of GPS since the 'we need more funding' report was published.....