[Loadstone] WAAS/EGNOS question

monty at loadstone-gps.com monty at loadstone-gps.com
Tue Mar 27 19:31:18 BST 2007


If your GPS receiver is capable of receiving WAAS/EGNOS augmentation, it's 
enabled on your GPS receiver, and  you're in an area served by WAAS/EGNOS, 
then you can query Loadstone to find out whether it is currently being 
used or not.  If it is being used, the message "Differential GPS fix" will 
be returned upon the query.

When the Loadstone/WAAS/EGNOS setting is set to "On", it will attempt to 
send the NMEA compatible command to your GPS receiver every time 
Loadstone is started.  Not all receivers 
are designed to listen out for the standard NMEA command so for the moment 
there really isn't a way to know for sure if the command took other than 
by querying the Loadstone/GPS signal status.

Wikipedia has extensive information regarding WAAS and EGNOSif anyone 
wants to know more about the systems.


Best regards,

  On Tue, 27 Mar 2007, Paul Hopewell wrote:

> Hello,
> I am using a Holux slim 236 with a Nokia 6600 running  the latest version of
> Loadstone. I have a couple of questions about WAAS/EGNOS.
> I was interested to read in a recent post that you can tell whether WAAS /
> EGNOS is on by hearing "differential GPS fix" when you press the 3 key while
> in navigation mode. I have tried this on several outings but have only heard
> "differential GPS fix" on rare occasions. I normally hear "GPS fix". My
> questions are:
> 1.	If WAAS/EGNOS is working should I hear "differential GPS fix" every
> time I press the 3 key, or is WAAS/EGNOS only triggered if there are
> insufficient sattelites in view for a good GPS fix?
> 2.	Is the WAAS/EGNOS signal broadcaste from a terrestrial station?
> 3.	Does WAAS/EGNOS cover all geographic areas or is the WAAS/EGNOS
> signal weak with uncertain reception in many places. Note I live a few miles
> outside Southampton in the UK.
> 4.	How accurate is a "differential GPS fix" compared with a "GPS fix".
> Many thanks for your help.
> Paul Hopewell
> hopewell at hopewell.org.uk

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