GPS units elevation accuracy

[Not the Autorx Frank]

I'm looking for a hand held gps unit with an altitude accuracy of +or- 1", Anyone know of such a thing???????

 

[thooks]

Not that I know of.

GPS is positioning you (rather the data receiver) at a point that has been determined through satellite triangulation.

I know of no way to triangulate elevation using a simple GPS receiver.

Using a Total Station or similar surveying machine with GPS and a rod would help.

But you are well into $30k at that point.


Do you need that?

 

[BrianWC]

I use GPS for work regularly and can tell you for a fact. Elevation is horrible on ANY consumer unit without an electronic altimeter. That's why the altimeter/electronic compass versions usually are more expensive. There are some fairly cheap ones, though. The Garmin eTrex has an altimeter version.

 

[Jim74]

My Magellan Meridian gold triangulates elevation. Not sure how accurate it is though.

 

[moribundman]

Try the friendly guys at DARPA or Q at the MI6.

The elevation measurement on my current GPS units is is shifty at best and pretty much unreliable. I wouldn't trust it.

 

[eljefino]

Altitude seems to be less precise on my GPS units than lat/long. I assume this is from the geometry of the look angles for the satellites it's using. I.E. if they're low on the horizon a small change in distance multiplied by a sine (cosine?) of that sliver of an angle introduces a fairly large error.

In Death Valley we stopped at a sign for the lowest point below sea level, and our GPS was off by ~40 feet.

I wonder how land-based enhancements, like WAAS, help altitude.

During the hurricane, I saw a cable news reporter indicate her satellite truck was 11 feet above sea level (I assume through its GPS) and all I could think of was my 40 foot error.