[ntp:questions] Re: Fixed-location GPS mode?

Richard B. Gilbert rgilbert88 at comcast.net
Fri Jun 2 02:39:46 UTC 2006


David J Taylor wrote:

> Folks,
> 
> I seem to recall reading somewhere that you could tell a GPS receiver 
> where it was, so that the PPS signal would depend on fewer satellites - 
> i.e. you didn't need four visible satellites to get a complete 3D fix all 
> the time.  Perhaps I simply mis-understood the purpose of the "initial 
> location" command?
> 
> Did I dream this?  Does the GPS 18 LVC have this option and, if so, what's 
> the correct NMEA command to enable "fixed position" operation?  Has anyone 
> tried this - what improvements did you see?

The Motorola Oncore receivers are capable of a "position hold mode". 
You first do a site survey, averaging 10,000 fixes, to determine your 
latitude, longitude, and height.  You put this information in the Oncore 
  driver configuration file, the driver reads it from the file and 
writes it to the Oncore then sets the Oncore to "0D Mode".  One 
satellite is then sufficient to give you the time.

I have no way of knowing if the GPS 18 LVC has this capability.  If the 
Garmin does have the capability, the NMEA driver would have to implement 
it.  I'm not familiar with the NMEA driver either. . . .




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