Hi Dave I dont think its the phase mod that is creating the "Dalek effect".
I think this is more likely to be interference between the two signals.
Westerglen is not "controlled" (should be "measured" really) by NPL though
it does have a rubidium source. Could the Dalek effect be due to the time
delay in the program modulation reaching Scotland there must be up to about
a millisec. That means there is only very slow fading as the carrier phase
difference is fairly constant but the mod is out of phase and beating. I
know the wide area quasi sync PMR systems beloved of Pye-Philips (and
laterly Simoco) used to have audio delay lines for equalising the delay
between sites, as well as ovened crystal reference standards (the old
HS400).
Cheers de Alan G3NYK
----- Original Message -----
From: Dave Pick <[email protected]>
To: <[email protected]>
Sent: 02 December 2005 15:56
Subject: RE: LF: loran c closure
That phase modulated data is a real pain. In the Scottish borders
Droitwich
beats with Westerglen (between Glasgow and Edinburgh) which either doesn't
have phase mod data, or has different data on it. The net result sounds as
if the Daleks have taken over radio 4. Surely there are better ways of
signalling to electricity meters or whatever it's for?
Dave G3YXM.
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Johan Bodin
Sent: 02 December 2005 11:14
To: [email protected]
Subject: Re: LF: loran c closure
Warren,
> BBC 4 from Droitwich on 198 kHz is kept in very close tolerance by
the
NPL.
> http://www.npl.co.uk/time/droitwich_bulletin.html
Yes, but it is not so easy to use "right out of the box" because it has a
lot of phase jitter (intentional PSK) that has to be smoothed out.
73
Johan SM6LKM
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