Message-ID: <000401c36f09$ae1052c0$6507a8c0@Main>
From: "Alan Melia" <Alan.Melia@btinternet.com>
To: rsgb_lf_group@blacksheep.org
References: <5.1.0.14.0.20030829155231.02af4b10@gemini.herts.ac.uk> <5.1.0.14.0.20030830124931.02a8cdf0@gemini.herts.ac.uk> <002201c36efa$6e12a1a0$045bfea9@RSGB613192>
Date: Sat, 30 Aug 2003 16:16:22 +0100
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Subject: Re: LF: Re: GPS-locked PSK tests
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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
alan.melia@btinternet.com


----- Original Message -----
From: "Andy talbot" <G4JNT@THERSGB.NET>
To: <rsgb_lf_group@blacksheep.org>
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 <j.r.moritz@herts.ac.uk>
> To: <rsgb_lf_group@blacksheep.org>
> 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
> >
> >
>
>