If Droitwich is passed through a 1Hz bandwidth filter there is no sign
whatsoever of the residual phase mod. I was receiving 198k this morning
before deciding to change to 77.5 for the evening run. DCF77 still hadn't
moved by more than 0.5 degree at 1700z.
Andy G4JNT
----- Original Message -----
From: Alan Melia <[email protected]>
To: <[email protected]>
Sent: Saturday, August 30, 2003 4:16 PM
Subject: Re: LF: Re: GPS-locked PSK tests
Hi Jim's idea of monitoring Droitwich might not be so good. Don't forget
there is a 22.5deg. (or somthing like that) phase shift keying on the
carrier, for control purposes. Unlike DCF39 the residual phase shift over
a
period is zero. (so I suppose it might be alright taken over a long enough
period) MSF,HBG, and DCF77 only have the on-off keying I think. On the
other hand ....there is a challenge to decode it !!
I will be interested to see any results of phase plots as these have a
bearing on some of the skywave propagation variations I am try to
understand. With conditions as they are at present you should see some
interesting shifts over night.
Cheers de Alan G3NYK
[email protected]
----- Original Message -----
From: "Andy talbot" <[email protected]>
To: <[email protected]>
Sent: 30 August 2003 14:27
Subject: Re: LF: Re: GPS-locked PSK tests
> Just for a bit of a challenge I've just set up the receiver monitoring
DCF77
> on 77.5kHz, with the Caesium beam turned on for the first time in over a
> year. It was very disconcerting to find that I was teh cause of the
> freqeuncy drift in last night's test ! Using just the crystal
oscillator
> part of the freq standard resulted in 7*10^-10 frequency error.
>
> So far, after an hour of monitoring using a 30 second integration
period,
> the vectorscope plot of DCF77 has not moved more than 0.1 degrees - and
that
> is most likely due to quantisation effects
>
> I'll leave it running over the day-night transition and see what
transpires.
>
> Andy G4JNT
>
>
>
> ----- Original Message -----
> From: James Moritz <[email protected]>
> To: <[email protected]>
> Sent: Saturday, August 30, 2003 1:30 PM
> Subject: Re: LF: Re: GPS-locked PSK tests
> > For long distance communications, it will be interesting to see what
> effect
> > sky-wave propagation has on the stability of the phase of the signal -
I
> > suppose this could be investigated by looking at some of the stable
> > broadcast signals thare are around - MSF, HBG, Droitwich, etc. Using
this
> > type of system, it should be fairly easy to see the phase changes
produced
> > by the ionosphere moving around. > I hope to do some more tests during
the
> week with lower power levels, etc.
> > as G4JNT suggests. At the moment, the PSK signal is generated by
simple
> > hard-wired logic - the length of the 12 bit "message" is fixed, but
the
> bit
> > period can be changed quite easily. If anyone has ideas for
interesting
> > experiments, please let me know.
> >
> > Cheers, Jim Moritz
> > 73 de M0BMU
> >
> >
>
>
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