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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