I've noticed a curious odditity on a Motorola M12 GPS module, when
started
up completely from cold with no stored almanac data: When the
module eventually 'appears' to lock up and show the correct lat
/long and
the NMEA data showing satellite staus 'Valid', the NMEA reported
time is 15
(ish) seconds out. Which means it hasn't downloaded the
leap-second
correction yet and is still working on GPS time - the NMEA report
gets
corrected after a minute or two longer wait.
BUT... Why does it decide that it has enough info for location
calculation
when it clearly hasn't yet downloaded all the almanac data ?
It's lying. Has anyone met this?
Only the M12 behaves like this out of those tested. All other
modules I've
used, including the older Motorola. Oncore,. give the correct time
immediately they show lock. Of course, if the internal battery is
alive
the almanac data is already stored and it jumps into life
immediately with a
warm start, but after several months of storage - sometimes just
weeks -
this battery goes flat.
Andy
www.g4jnt.com
