[time-nuts] FE-5680A arrived

[mike cook]

Le 11/01/2012 19:36, mike cook a écrit :
> Le 11/01/2012 19:24, Chuck Forsberg WA7KGX N2469R a écrit :
>> The FE-5680A 1pps is not sync'd to UTC.
>> According to my calculations, it would take several hours
>> to walk the 1pps to UTC given the 3.8e-5 adjustment
>> range via the RS232 input.  A thunderbolt, an arduino,
>> and patience.
> You don't need to take the walk. Just fudge the ATOM driver time1 
> parameter after scoping the offset between GPS PPS and 5680A PPS 
> signals. You would need to reset it on a Rb power cycle though.
>
just thought of something else which worked for me and may be of use.

  If you don't have a scope or TIC to  get the Rbs PPS offset from GPS, 
you can let NTP do it for you.  You need a stable reference such as GPS 
to be set up as a prefered server,  then set up the atom driver for the 
5680A with no offset and prevent selection with "noselect" parameter and 
or push the stratum from 0 to 8. Once NTP has been running a while, the 
offset of the DUTs PPS will be seen in the ntpq -pn output. You can plug 
that in as the DUTs fudge time1 parameter and restart ntpd. You may need 
to iterate.
ex.
  server 127.127.22.1 minpoll 4 maxpoll 4 noselect
  fudge  127.127.22.1 stratum 8 refid PPS1 time1 0.000000 flag3 0 flag2 
1 # enable PPS module

      remote           refid      st t when poll reach   delay   offset  
jitter
==============================================================================
  127.127.22.1    .PPS1.           8 l    9   16  377    0.000   
-1.268   0.093
*145.238.203.14  .TS-3.           1 u   67   64  377   34.473    1.572   
0.399
      remote           refid      st t when poll reach   delay   offset  
jitter
==============================================================================
  127.127.22.1    .PPS1.           8 l   11   16  377    0.000   
-1.528   0.038
*145.238.203.14  .TS-3.           1 u   19   64  377   33.300    0.217   
0.750

ntpq -pn only gives usec resolution displays but ntpd calculates in 
nanosecs. You have to have logging enabled and look at the peerstat data 
if you want that.