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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