Geocaching Australia

What's new? Been this way for the past 10 years.

GIN51E wrote:Might be worth checking out this site http://www.prestigecom.net.au/

Lots of goodies including Epirbs and PLB's

That site has some extremely bad misconceptions with the heading "Spot EPIRBS & PLB".

SPOT is neither an EPIRB or a PLB not even close.

I believe GRAS uses frequencies on the VHF band for its transmissions so that would usually limit them to near line of sight? I would have thought once you began covering a large areas the cost of additional transmitters would exceed the cost of a SBAS. Then again satellites do cost a LOT of money....

I would be interested to know in what ways it was more advanced if you know. I haven't been able to find much freely available technical info on the GPS signals. The thing with GRAS is that it is inexpensive compared to WAAS, ICAO certification was basically complete, and it worked, all in all ahea...

I believe that although the 121Mhz beacons are not recognised by satellite, but passing aircraft will still be able to pick up a signal. Over flying aircraft are definately not something to rely on for 121.5 detetction. SPOT is not an alternative for an EPIRB but does have some features some may be...

WAAS will not be installed in Australia.

Some of the existing AirServices VHF network is being used for GRAS which in fact is more advanced than WAAS and has also been installed in the US. In other words GRAS works WAAS doesn't.

....If you leave you GPS at the cache with a clear view of the sky while you log the cache, you may find that the distance from your original GZ may actually get closer to where you are now standing. Then again it might also move further away couldn't it? The thing is you really don't know if the p...

Well then you don't have much background to the relationship of actual cell tower coordinates and the ACMA database but don't let that get in the way of your understanding. Telstra actually had a call back SMS position system in place but as lonjg as you were only expecting something between 500 met...

For a start the tower coordinates are basically classified and second if phone tower based systems were any good then the 000/911 tracking would have been solved long ago, but it hasn't becasue it is in no way reliable or accurate enough.

Conversion GDA94 <> AGD66 is really quite simple using freeware such as GDAit or GDAy etc and the appropriate NTv2 distortion grid.

Now back to jammers!

Arh the principles of relativity and yet your poor little handheld GPS knows how to handle the satellites orbiting at 4000m/s as well as earth spin, orbit and time/clock principles to give the accuracy they do at low cost. I know we're moving northish, but the quoted 7cm, is that with respect to WGS...

WGS84 is obviously still based on a set of fixed points Fixed points? oh now once we start talking about ITRF then everything is going to get a little complicated, not going there :wink: I think this is where you think your 10cm might be as the reference frame for GDA is ITRF 1992, not going there ...

I'm sure if there is disputes over boundaries and surveyours are called in they will be using some reference points to sort the matter out, to derive where the property boundary is. Any reference will have absolutely nothing to do with cooridinates (as such), pegs, pins, posts, trees, fences, nails...

From what I've read it was 0cm when they did the inital survey(s) in 1992, and was more like 10cm out by 1994. In 2000 the gap was supposedly about 45cm and by the start of 2005 the gap was at 75cm, check the thread in QLD caching for the relevant references. I estimated the gap to be about 100cm b...