Message-ID: <001901c36f1a$cef98e00$045bfea9@RSGB613192>
From: "Andy talbot" <G4JNT@THERSGB.NET>
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$045bfea9@RSGB613192> <000401c36f09$ae1052c0$6507a8c0@Main>
Date: Sat, 30 Aug 2003 18:18:44 +0100
MIME-Version: 1.0
Subject: Re: LF: Re: GPS-locked PSK tests
Content-Type: text/plain; charset=iso-8859-1; format=flowed
Content-Transfer-Encoding: 8bit
Sender: <owner-rsgb_lf_group@blacksheep.org>
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org

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 <Alan.Melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
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
> 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
> > >
> > >
> >
> >
>
>