[ntp:questions] Ultralink 325 WWVB receiver

Rob Kimberley time.bandit at btinternet.com
Sat Feb 16 19:35:23 UTC 2008


> behavior I described before in the 24 hour pll offset plot.  Interestingly
> though, viewing the seven day "offset as viewed from janus" plot shows a 
> regular but much larger swing +-40 ms.  Notice also the swings in the 
> seven day frequency graph mimic the swing intervals on the "offset as 
> viewed from janus" plot.
>
> Here are the plots:
> http://saturn.dennishilberg.com/ntpstats/rrdtool/apollo.php
>
> I really don't know what to make of the data, so any help would be 
> appreciated.
>
> Thanks.

Interesting plots! Have tried to make some sense of them, but rather 
difficult.

1) How is the Rx powered? (I don't know the product)
2) Do you know what type of oscillator is used in the Rx, and how it is 
supposed to be controlled?
3) The changes in offset don't appear to follow any regular 24 hour pattern, 
so would tend to rule out diurnal effects, plus the changes are much larger 
than one would expect. I notice a large step around 02:00 on a Saturday. 
Does anything large get switched off/on at this time? Thinking along the 
lines of some sort of power surge causing interference to the receiver.

More later (and apologies for the delay in replying)


Rob Kimberley





More information about the questions mailing list