New to GPS world !! Help needed

[Wattman]

I have recently purchased a copy of Terrain Navigator 2001 and plan to use it to locate telemetry project sites. I probably should have asked for a recommendation here first but it's in the mail and should have it Monday. I selected the software for it's 3D effects and download ability of waypoint from a GPS.

I plan to use the equipment for various site studies required for telemetry equipment and it seams the GPS and software will likely will be a great tool to assist in these type projects and would allow the most efficient choice of radio equipment.

I plan to purchase a mobile GPS unit, and have found the prices to be cheap too outrageous. I would like to purchase a accurate and reliable GPS unit for engineering type work, rechargeable maybe via truck and/or 120 VAC or maybe a unit that has charging unit in a vehicle.

I'm New to the GPS world and would appreciate any advice on software and a GPS unit.

Please advise

 

[RETM]

I DO REPORT ABOUT MODERN POSITIONING SYSTEM CAN YOU HELP ME ?

 

[IRstuff]

It all depends on what accuracy you're looking for. Satellite coverage and visibility are primary actors in the overall accuracy, but even in the best case, you're looking at double-digit feet circular error probables.

If you're trying to do surveying and or accurate terrain mapping, you're looking at a differential GPS system that uses a fixed ground station with known, accurate position. The fixed station broadcasts a position correction to the portable receiver on the assumption that geographically co-located receivers will come up with the same position errors at the same time.

TTFN

 

[carlorom]

Irstuff is correct with his response - Accuracy will depend mainly on price.

Handheld GPS such as Etrex etc are relatively cheap but will give at best around 5m - more usually 15m accuracy - Height is usually the worst.

There is a system called WAAS which claim to give accuracies to around 1m but it depends on ground station data and is generally only available in certain areas - so check with the GPS vendor. I know of one GPS which will give heights based on barometric pressure as well and should be quite accurate provided it is calibrated properly against known points.

Also check what co-ordinate systems the GPS units support or the software that comes with it. Each country /area has its own system and conversions may be required from WGS84 to that system - This is quite a complex field but there are software packages which will do these comversions - again it needs a bit of research locally. This is especially important if you are going to link to other surveys.

The more expensive high accuracy survey systems require two specially designed receivers - companies like Leica and Trimble can advise on their products and accuracies.

So it all depends what you want to do with the GPS.

I hope this helps?

 

[clems05]

I am not familiar with the handheld market, however a friend of mine is interning on a project where the handheld GPS unit is also a data collector ( i know you don't need all that) being used to collect data on every culvert catch basin, etc. for future GIS/hydro modeling. but it apparently has sub metre acc due to capabilty of using a subscription that gives you this acc w/ out diff. In other words, I would look for a GPS unit that maybe used with these extra bits of data that are received in result of having one of these subscriptions.

goodluck on your investment