[OSM-talk] Defective GPS trac

[Chris Hunter]

Sorry about the formatting on the quoted part. I'm writing from my BlackBerry. 

IIRC all of the correction stations (WAAS / EGNOS / etc...) are listed at or above satellite number 45 on your satellite / accuracy screen.   

An easy test is to go to an area with a clear view of the sky and take a reading on a stationary object.  Come back to that spot a few days later and remeasure.  If your second measurement is off by more than 25 feet (about 5 meters), then try toggling the WAAS option and see if your accuracy improves. 

If you are near an urban area, search the web for a local Geocaching club and read through their tech forum if they have one.  BTW, geocaching clubs are great sources for raw GPS traces.  Most cachers own at least one dedicated off-road GPSr with the snap-to-road option toggled off, so there won't be any issues with tracing off of a copyrighted map. 

On Sat, Jan 2, 2010 at 8:17 AM, Aun Johnsen ‪<lists at gimnechiske.org>‬ wrote:
>The  accuracy shown on your GPS unit is not necessary the actual accuracy, but just a calculated accuracy depending on the signals your unit is receiving. You can experience athmospheric disturbance, plasma-effects, signals reflected off tall buildings, canyon or urban canyon effects, bed satellite constillations etc. If you have SBAS (WAAS/EGNOS) activated you might see an improvement in the signal, but mind that if you are outside the official coverage of such systems you might experience that these corrections are in fact increasing the error. 

> I switched the WAAS capability on the GPS on, but again, I don't know if it's actually doing anything.

Steve
Sent via BlackBerry from T-Mobile