[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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