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

SAIDJACK at aol.com SAIDJACK at aol.com
Fri Mar 31 04:51:33 EST 2006


Hi,
 
if I remember my statistics correctly:
 
1-Sigma is the standard deviation of all measurements. 6-Sigma is something  
like 99.997%(?) of all measurements, basically all relevant measurements.
 
Keep in mind that the Motorola GPS need to be initialized by a binary  
string, they will not produce any output signal until initialized.
 
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  
behaves.
 
The Clock Granularity message is to be applied to the next following 1PPS  
pulse in Motorola speak. Typically, the 1PPS is captured by a Microcontroller,  
which can then add the granularity message data to the capture time, and thus  
improve the measurement over the long term.
 
bye,
SJ 



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