GPS or WAAS/EGNOS

WAAS / EGNOS help improve the accuracy of your location readings. More info at this page

http://www.how-gps-works.com/glossary/waas.shtml

JM

Would you leave it on all the time?

I would suggest it unless you're using your GPS unit strictly on batteries. My eTrex Legend is WAAS enabled, and the battery time is cut about in half when I use it on the lake with WAAS turned on. I get about 12 hours out of it without WAAS. I get about 5.5 hours with WAAS enabled.

So, yes it's more accurate as you're basically triangulating your location along with the standard Satellite read, but it eats power.

appreciate the help

Hello,

New guy here... Just got a Garmin C530 for Christmas.

Haven't checked out the above suggested WAAS site yet. So, this may be a stupid question...

I retired from the Coast Guard, back in 2000. Before retiring, I was co-managing (at CGHQ) the Differential GPS project, with a Congressional Mandate to establish a DGPS system across the USA. I retired during the early planning phases of this project. Is WAAS/EGNOS related to DGPS?

Thanks!

OK... Just visited the site...

I see the FAA actually got funding for the project they wanted to run parallel to DGPS. I also saw a system called WADGPS. If this is the same CG DGPS system I worked on, then this, at the time, required a separate MF DGPS receiver. I suspect that our Garmins do not work with WADGPS?(When I was involved, Congress was telling the FAA that they would not get funding and to participate in the CG's DGPS system.

Your suspicion is correct, and I don't think there are too many, if any, WAD enabled GPS receivers out there. They are quite large as they have two separate receiver circuits, plus embedded folded quarter-wave antenna, plus another board that ties WAAS/WAD/DGPS to one display. They are quite bulky from what I'm hearing. I haven't seen one myself, just speaking with a couple of Coasties out of NC back in April when I was on the shore.

And as you found in your research, WAAS and WAD are separate systems. WAAS utilizes earth stations differently than either WAD or DGPS.

The guys I spoke to said they figured it would be 5 to 7 years before a marketable unit was released for retail. Also the current unit those guys had required a separate antenna, so you had the embedded antenna for WAAS/DGPS, and a separate external for WAD.

So its a seperate system to make GPS more accurate, so if I have a car system that is powered use it?

Oh yes, if you've got a WAAS enabled GPS unit, I do highly suggest you use it. If your unit gives you an accuracy rating you may look at it before and after enabling WAAS.

My eTrex shows that, right now with it by the window, with WAAS disabled I have an accuracy of ±30 feet... enabling WAAS, it says ±9 feet. So you do gain quite a bit of accuracy. That also depends on if you have WAAS earth stations near you too, as they aren't 100% covering everywhere. I'll look for the link, somewhere I have a link to a site showing WAAS coverage.