[time-nuts] Precise manual survey (was Common sky pps...)

SAIDJACK at aol.com SAIDJACK at aol.com
Wed Jan 7 23:00:42 UTC 2009


Hello Peter,
 
we've got a number of different units running various tests in our lab  right 
now, and they all can be tracked on the following site:
 
   _http://www.jackson-labs.com/images/gpsstat.htm_ 
(http://www.jackson-labs.com/images/gpsstat.htm) 
 
The units will flip-through the website every 30 seconds or so.
 
These are two 3D Fix units, and two Fury's running in position-hold  mode. 
>From looking at their position indicators, and doing some math I  found:
 
The two Fury units indicate position within <1 meter of each other in  X/Y/Z, 
so that's quite good.
 
The other 3D Fix units' position is constantly changing, and the height  
seems to be within ~4m, the position to within ~2m, this could cause some timing  
uncertainty ~10ns - 15ns I would think. That's the drawback of running  these 
units with dynamic 3D Fix mode and not in position-hold mode.
 
I think having all four units indicate position to within <2m without  
averaging is quite acceptable though.
 
bye,
Said
 
 
In a message dated 1/7/2009 08:02:59 Pacific Standard Time,  
pvince at theiet.org writes:

Thanks  Said.  A supplementary question, if I may: can you confirm that the  
phase
"wobble" caused would be a maximum of the usual 1ns per foot?   And am I 
right in
thinking that incorrectly specifying the antenna cable  delay will only 
affect the
accuracy of the timing of the 1pps output wrt  UTC, and not cause any extra 
wobble?

Thanks,

Peter





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