[time-nuts] Is possible precise 1pps?

SAIDJACK at aol.com SAIDJACK at aol.com
Wed Mar 13 13:43:21 EDT 2013

Hi there,
there can be a huge difference in performance, depending on how well  the 
antenna is positioned. We did a test here a little while ago to  see what 
happens to our uBlox receivers if they only see a sliver of the sky  (the 
equivalent of only about 20 minutes worth of sunshine through a  window). We ran 
them in mobile mode, and then switched to position-hold  mode.
The results are remarkable, see the attached plots.
Most of the time these units only see and track one or two satellites. With 
 position hold mode (right part of the plots), they work great. Without it 
(first  part of the plots) they are very noisy as the work mostly from 
multipath  signals.
I had posted these plots here previously and was criticized for doing so,  
because I did not make it clear that these plots show the actual GPS  
receiver performance, and the performance has nothing to do with the  GPSDO's they 
are part of. Hopefully this clarifies the significance of these  test 
In a message dated 3/13/2013 07:03:16 Pacific Daylight Time, lists at rtty.us  

From:  time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of  hutta.j at seznam.cz
Sent: Wednesday, March 13, 2013 9:04 AM
To:  time-nuts at febo.com
Subject: [time-nuts] Is possible precise 1pps?

I  have GPS without  "position hold", I wonder how precise 1PPS, which I  
to use for disciplined OCXO.
You do not know how GPS with "position  hold" calculates the measured 
coordinates vs know the real coordinates of  the expected error timestamps 1

Thansk for  information
time-nuts  mailing list -- time-nuts at febo.com
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