[time-nuts] GPSDO recurring Time Interval aberation

[SAIDJACK at aol.com]

Hi there,
 
this could also be caused by a slight error in the Auto Survey  position of 
the Fury GPSDO.
 
The M12 does the auto survey over 3 hours, so you are limited to the  
accuracy and constellation of the Sats during that time period. You could try  the 
following to improve your position accuracy:
 
1) Write down your present hold position.
 
2) Do another auto survey, preferably at night if you did the first one  
during the day, or during the day if you did it at night etc.
 
3) Average the two resulting positions, pay particular attention to  Antenna  
height. For example if you get a height of 45 meters and 47 meters  from the 
two measurements, use 46 meters as the averaged result.
 
4) Enter the averaged position into the unit manually by using the:
 
   GPS:POS
 
and:
 
   GPS:POS LAST
 
commands.
 
5) Repeat from 1) as necessary.
 
Additionally you could try:
 
6) Increase your Mask angle from 10 Degrees with the command  
GPS:SAT:TRAC:EMAN 20
 
7) Make sure the M12 TRAIM is turned on with the command:
 
   GPS:REF:TRAIM ON
 
Hope that helps,
bye,
Said
 
 
In a message dated 12/20/2008 12:40:28 Pacific Standard Time,  
kc0ukk at msosborn.com writes:

I've  been tracking my Fury GPSDO (ROM version 1.21) equipped with an
Isotemp  OXCXO134-10 oscillator for a couple of weeks now and have
noticed that the  Time Interval (TI) spikes around 20 to 40 nsec
everyday at 17:45 UTC (11:45  AM CST local time). There are minor
spikes (5 nsec) every 2 to 3 hours, but  I find the large spikes to be
very curious.

The oscillator itself  has no idea of the time of day (does it?), the
Fury generated EFC follows  the spike and brings the TI back into line
within tow or three  minutes.  There are no unusual charges to the EFC
prior to or after  the spike.

I've already tracked ambient temperature over several days  and have
seen nothing unusual. I'm going to monitor line voltage  next.

Has anyone else ever seen such behavior?

-- kc0ukk at  msosborn dot com