[time-nuts] WWV 12 Hz doppler shift

[Graham]

You don't need a fully synthesized radio to this type of monitoring. I 
have used my very old kenwood TS-520 to do this but with an external DDS 
vfo. The receiver did drift but only due to the radios two crystal 
controlled other oscillators.

I have been using my ICOM R-75  which has the stability crystal 
oscillator and Spectrum Lab to monitor CHU on 7850 KHz for a similar 
purpose. I have attached my plot which shows the effect on CHU's signal 
for this  X class flare event.

In the plot, the more or less steady solid line in the middle is CHU's 
ground wave signal as received at my location. It doesn't vary but my 
receiver varies slightly; about +/- hz or so due to warming and cooling 
of my radio room. The varying signal is the doppler result of the 7850 
KHz carrier being reflected by the moving ionosphere. I live 25 miles 
from the CHU transmitters so I receive the ground with very good 
reliability. At approximately 17:48 you will note the doppler shifted 
signal go almost straight up exceeding 2 Hz - the bandwidth of my 
display is just shy of 4 Hz and had it been sufficiently wide enough I 
would have seen the extent of the shift. All times are UTC.

It is fascinating to observe the diurnal effects and when the timing is 
right, the effects of such an flare as this past weekend.

An ongoing project is to build a GPS disciplined receiver using a 10 MHz 
OCXO master oscillator and DDS for this type of monitoring. It will 
likely have an embedded Arduino to handle some mundane control and 
logging functions so the recent discussions on Arduino GPSDO etc have 
been quite interesting.

cheers, Graham ve3gtc



On 2014-03-31 21:32, nuts wrote:
> On Mon, 31 Mar 2014 13:54:04 +0200 (CEST)
> "iovane at inwind.it" <iovane at inwind.it> wrote:
>
>> Seehttp://www.spaceweather.com/  Antonio I8IOV
>> _______________________________________________
> I had considered modifying one of my fully synthesized radios to use a
> GPSDO. Now I regret not getting around to doing this since I could use
> it to see this shift.
>
> TDB.
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