[ntp:questions] MSF outages

Mr Dave Baxter g8kbv at uko2.co.uk
Mon Jan 3 18:56:35 UTC 2011


In article <uhpuu7-jvs.ln1 at p4x2400c.home.lordynet.org>, 
snews at lordynet.org says...
> 
> Hi
> 
> I have an MSF clock from a converted Conrad DCF module
> that has been ticking for over for most of 2010. I've
> been  assembling a DIY receiver but keep hitting a brick
> wall. On looking back at logs from my Conrad module now
> see that the 'brick walls' were all at periods when MSF
> was not being received by the Conrad module either.
> 
> I can understand the service being down due to the
> severe weather but there is no indication of this on NPL
> MSF status page.
> 
> Anyone else having problems receiving MSF?
> 
> Today the modulation level appears to less than 50%
> rather than on-off modulation.
> 
> 
> David

Hi.

In an urban environment, the background noise level at 60kHz can be 
embarrasingly high at times, what with all the SMPS powered gadgets that 
litter the place, some 'phone chargers when left in a socket and 
powered, but with no load, are particularly noisy!   EM polution etc.

Many "consumer" grade MSF/DCF RX's are not much more than a tuned 
circuit and a detector, that will not reject any other noise that well, 
so you see a less than 100% on/off modulation.

I once had a synchronous MSF RX, that was extremely good at rejecting 
noise.  Wish I'd never got rid of that now.

I had a listen recently with a LF communications RX, that is spec'd to 
go down below 60k, and with bandwidths down to 200Hz, the background 
hash at my location (probably much of it is mine!) was a real eye 
opener.   Thankfully, my own NTP servers are locked to GPS, but I do 
from time to time use a 'scope triggered to a GPS/PPS signal, just to 
check the state of the MSF signal/noise levels.

When it was radiated from Rugby, no problem.  Since the move to Anthorn, 
though the signal level is within the projected spec's, the background 
noise level is now so much higher % wise, than it was before.

Oh, I'm located in North Bucks (UK)

Cheers, and Happy New Year and all that.




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