DPRG mailing list archives: [DPRG] WAAS success on GPS...

Mon Jun 2 10:31:57 CDT 2008

Randy,

Yes.  There are two things to watch for.  1) the unit does not always seem
to get the command so you have to monitor for the response and after a time
out, send again if required.   2) Wait, wait and wait some more.  Once the
unit has been enabled to search for the SBAS satellites it takes anywhere
from 2~7ish minutes.   I haven't particularly paid attention to how long it
takes, I just have a mental note that it is an annoying amount of time
related to the analyze, code, test debug cycle.

	Command: $PMTK301,2*2E	Response: $PMTK001,301,3*
	Command: $PMTK313,1*2E	Response: $PMTK001,313,3*

I have found that waiting for a significant amount of time (> 15 seconds)
after power up greatly improves the likelihood of first time command
execution success.  In ProtoBot this is easily accomplished by moving the
initialization order for different functional sections during boot.

*Note, I am not using a low power battery backup and that *may* impact all
of the above as the unit may retain these setting, or, it *may* remember
which satellites and where since the satellites carrying the corrections
signal, unlike the remainder of the constellation, are geostationary....

-Kenneth

-----Original Message-----
From: Randy M. Dumse [mailto:rmd at newmicros.com]
Sent: Monday, June 02, 2008 10:16 AM
To: 'Kenneth Maxon'; 'DPRG'
Subject: RE: [DPRG] WAAS success on GPS...

Kenneth Maxon said: Sunday, May 04, 2008 2:05 PM
> I'd like to report Success in (after all this time) getting
> WAAS signaling back from the SMIRF(III) chipset.
>
> At the root of the problem I uncovered that not only do the
> WAAS message formats have to be enabled (301), but one also
> has to send commands to
> instruct the module to enable searching for the SBAS
satellites.   The
> message is "$PMTK313,1*2E<CR><LF>"

So am I understanding correctly for SiRF III that you send

$PMTK301,2*2E<CR><LF>
$PMTK313,1*2E<CR><LF>

And the WAAS should work?

Randy