Richard B. Gilbert wrote:
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. . . .
I'm almost certain it does not have Zero-D mode, what it could have is
2-D mode, i.e. for use in a boat, where the altitude by definition
really shouldn't change. :-)
This will only save one sat though, so it is no replacement for a proper
timing receiver which can instead use multiple sats in Zero-D mode to
determine if one (or more) of the satellites are currently sending bogus
info.
I believe Motorola called this TRAIM.
Terje
--
- <[EMAIL PROTECTED]>
"almost all programming can be viewed as an exercise in caching"
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