Hi Peter,
I have carried out the same comparisons again ie. 60KHz, 75KHz & 77.5KHz
against 198KHz & BBC 198KHz is 1Hz high, tested at 2035z. Could there be an
error in respect of the frequency difference in the receivers band set up
although I believe the range is in the same band on my JRC NRD-345. When
compared with DFC39 (accuracy of this station not known to me) there is a
difference of 0.5Hz. Is there another accurate signal nearer 198KHz with
which to compare?
73,
Gary - G4WGT
-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Peter Martinez
Sent: 07 June 2006 21:20
To: [email protected]
Subject: LF: Re: RE: BBC 198kHz
>From G3PLX:
On seeing the report of Droitwich being off frequency, I connected up my
Clicklock set-up, which enables me to measure off-air signal phase relative
to GPS.
I have to run the system with no antenna in order to get Droitwich low
enough in level, and that makes the measurement a little sensitive to
disturbances in the shack, but this is a disturbance in both amplitude and
phase, and it's quite easy to see that the few degrees wobble I am seeing in
the phase is the same as the wobble in amplitude, and is not due to a
systematic drift in phase. A random distrbance results in a blob on the
vectorscope. A frequency error shows as an arc around the origen.
If it had been 1Hz off, I would have expected to see a change of 360 degrees
PER SECOND, i.e. a full circle rotating once/sec. All I can see is a
circular blob about 2% amplitude, and that's over the last 20 minutes.
I would say Droitwich is spot-on. Has anyone who saw it off frequency
checked it again (since 20:00 utc) to see if it's back on frequency? Was it
off frequency and it's back again, or maybe it was never off.
73
Peter
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