[time-nuts] ...Your thoughts on the Trimble Resolution T?

Brooke Clarke brooke at pacific.net
Fri Mar 31 15:50:40 EST 2006


I'm not sure if Trimble does it on the Resolution T, but on the Trimpack 
GPS receivers,
have a Lithium battery soldered to one of the PCBs and a Dallas chip 
that turns all the RAM into non volatile memory (just like core memory 
in operation).  This means that when powered up it not only has the 
almanac and ephemeris data for all the satellites it also has the fix 
information so the warm start time is very short.  They say if the 
receiver is moved more than 100 km TTFT will be longer.  My Trimpacks 
which were built in the 1990 (Gulf war) time period all have good 
batteries, so the current needed to do this must be very small.

The sawtooth correction can be used with hardware to move the 1 PPS edge 
or it can be used in software where a computer does the math on the 
measured time interval.

Have Fun,

Brooke Clarke, N6GCE

SAIDJACK at aol.com wrote:

>  .  .  .
>Also, the Motorola parts have one drawback: they need a Lithium battery (or  
>similar) to keep the most recent Almanac. I have found that the TTFF (first 
>fix)  can take quite long if the battery is weak (<2V) and the RTC stops due to  
>this, or if there is no Almanac in Memory. Don't know how the Trimble unit  
  .  .  .  .

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