OT: GPS unit for survey

Thanks John. It's the absence of magnetic variation/deviation with GPS that is of interest.

Jordan

John wrote:

I know that this is just me being macguyverly again, but did you know you can make a really good GPS unit out of weather balloon instrument packages? They use DGPS so you have to have an initial known location, but apparently they're pretty accurate. I used to have a website about it bookmarked but I can't seem to find it now, I'll google it later. The other thing is that if all you're after is a rough estimate, use the GPS in your cell phone. Almost all cell phones report it now, and many have APIs for it. Nextel offers an easy-to-use pay service that will cost you much less than a new GPS. Just my two bits. GCC

Strap sez:

"Have you found Garmin screen size to be a drawback?"

No. Certainly not on such a simple display as that of the 10 year old GPS

1. If, in the market for a new GPS, though, I would make critical comparisons of respective screen sizes.

Bob Swinney

For the basic Digital Globe satellite coverage, you can turn on an overlay that shows when the image was acquired, to the day. In the sidebar, go to Layers -> Digital Globe Coverage and check the box. Go up about 20 miles so you can see multiple sat image areas outlined in blue, with red dates.

In higher resolution areas, you can sometimes tell whose data you are seeing by the copyright notices on the screen. Right now (Sacramento, CA) I'm seeing Digital Globe, Europa Technologies, and Sanborn copyrights. If I turn on "roads", I also get a Navteq copyright. In San Francisco they credit only Europa and TerraMetrics, but there are still Digital Globe dates and boundaries visible.

Loren

Does Lieca make a laser DME for abt $300 , 5mm accurate , 2 PPM ?

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Nick Hull wrote:

Yes but it is limited to 325'