[time-nuts] Ublox neo-7M GPS

Ed Palmer ed_palmer at sasktel.net
Thu Aug 21 16:03:35 EDT 2014


Paul,

How far from the equator are you?  The farther you are, the more trouble 
GPS has measuring your latitude due to worsening geometry.

By the way, does anyone know what the timing effects of that will be?  
Is it documented anywhere?  I noticed that the GLONASS satellites have a 
higher orbital inclination than GPS.  Would a GLONASS Disciplined 
Oscillator perform better at higher latitudes than a GPSDO?

Ed

On 8/21/2014 12:52 PM, Paul wrote:
> On Thu, Aug 21, 2014 at 9:45 PM, Tony <tnuts at toneh.demon.co.uk> wrote:
>> I just tried sending various TMODE and TMODE2 configuration messages to the
>> NEO-7M. These allow you to select 'Disabled' 'Survey In' and 'Fixed Mode'
>> where you can specify the receiver's lattitude and longitude. Not
>> surprisingly, it replied with negative acknowledgements each time so they
>> presumably aren't supported in this receiver.
> Right, those are typically T version only commands.  It should be in
> the documents as a note.  The earlier list of timing attributes left
> out a critical one, being able to set your position to the accuracy of
> the receiver.  While it's probably my poor anttenna siting the various
> self-surveys (Tbolt, Res-T,  LEA-6T) I've done are all pretty poor.


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