[BC] GPS for Proofing (WAS:dBm, dBc, dBd)

[Cowboy]

On Wednesday 16 November 2005 03:45 am, Alan Alsobrook wrote:
>What is really nice is using the GPS connected to a laptop running 
>Delorme topoquads. I recently did a run in Ga (where I didn't have the 
>topo quads) and used the Garmin software, it worked just fine but I 
>still prefer the topoquads for field runs.

 Have not yet seen those. ( Delorme Topoquads )
 Remember, I'm a really chea..... er...... "frugal" sort of guy. ;-)
 I'm not inclined to run right out and buy a brand new super-high
 powered laptop with a gig of fast RAM just to be able to run
 WinXP, and therefore the only available versions of Delorme.
 The high cost(s) of M$ dependency, I guess....

 Like the Garmin software, except that they dropped real time tracking
 from their maps, so the newer versions require a new, super feature laden
 GPS unit, which I also don't want.
 Their older topo stuff is pretty good, though I do wish it had more
 selectivity in which "details" it will show.
 Sadly, to be of real use with a laptop, it requires old versions of their
 software which do have real-time tracking available, but other limitations.

>I haven't figured out all the in's and outs of it but there is a way to 
>load your radials into the GPS unit so that you will have your radial 
>lines on the screen. I understand this is easier with a GPS III than 
>with a GPS V (which I have). I'm guessing you load the radials in as a 
>route. I really haven't played with this yet.

 I have, but it depends on which version of the software you have.
 If yours does auto-route you don't get a radial, but get driving
 directions. Useless for a real proof.
 If you can turn off auto-route, then you get a line which is as accurate
 as the Garmin system, about 5 decimal places to a degree.

 I'm just not terribly fond of the map display on the GPS units, and
 prefer a laptop in the car.

 Short version is to find the reference tower as accurately as possible,
 then project a point beyond the end of the radial, and do a straight line
 route to that point.
 The accuracy is really good, but the resolution is limited to whole degrees.
 Remember though, that none of the GPS units I've seen display the
 accuracy they are capable of, and it decreases with distance, *especially*
 the distance displayed.
 Properly used, it can get within about 30 feet maximum error at any distance.

>Also you may be able to  
>set a point at the end of the radial your working on (in simulate mode) 
>  and do a direct navigation to the array center.  When working in on a 
>radial it's easy to get to the end of the radial and just hit goto and 
>poof an easy line to follow.

 Pretty much.

 My brother wrote a routine ( later modified by me ) that calculates the radial
 and projects reference points with a great-circle accuracy of some 15 decimal
 places, or within a few inches at any distance.
 The greatest errors in our system are the GPS accuracy itself.
 Most of the GPS units I've seen will only show a bearing to within 1/2 degree, so
 one can be off by a mile at distance depending on that function. Bad plan.
 The majority of the "project a point" stuff I've seen is only accurate to one degree,
 so that's even worse, which is why we wrote our own.

 There's a free linux GPS mapping package, but it's limitation is that no data maps
 are available, so it depends on one down-loading topo images, or satelite images
 of the area in advance.
 Other than that, it's a nearly perfect package, but is really intended for "war-driving."
 ( which is driving around and finding wireless "hot spots" not quite at random )
 *IF* it could use a data CD of some kind, it would be prefect.

 There's another free linux package that will use the shape-files from which
 USGS topos are produced, but I haven't gotten that to work properly, yet....

-- 
Cowboy

http://cowboys.homeip.net

What is this talk of 'release'? Klingons do not
make software 'releases'. Our software 'escapes'
leaving a bloody trail of designers and quality
assurance people in its wake.