Hi Wolf and all, thanks for leaping to the keyboard and massaging
SpectrumLab once again....it is doing sterling work. and makes the
monitoring of distant beacons so much more interesting (and useful)
I am not sure whether watching HBG and DCF77 will be of much interest at
your location Wolf. As far as I see it, we are mainly interested in using
these things as a cheap " ionospheric sounder ". So what I believe matters
at shorter distances is the difference between the day and night levels.
If maybe you are screened from some of the ground wave then there could be
interesting plots made. At my location of approx. 700kms from DCF39 I get
get a steady level during the day and some slight variation on that at
night, but only about + / - 6dB. This is probably the effect of equal sky
and ground wave paths at similar strengths interfering. Beyond about 900 kms
it starts to get interesting but the two "useful" European paths have been
DCF39 to CT1DRP at 1960kms (with some mountains and arid ground in the
way....so low ground wave levels) and SXV to G3NYK (over the Alps at 2350kms
...from memory) and SXV to CT1DRP again over 2000kms. Unfortunately ( for
some of us ....sorry Markus and Costas) SXV seems not to be using the 135.8
allocation very much in the last 15months. At about 2000kms there would seem
to be about 20dB or more between ground wave and night-time skywave, so that
the latter predominates. Of course the skywave is there are shorter
distances.....maybe this is where we start measuring the phase variation.
Because we know the phase of the arriving ground wave...maybe we could
interpret the results to give useful data...if we can measure and log phase
accurately enough, and do the stations transmit a reliably constant phase.
We know DCF39 does not, but others may be more useful....time data might be
a problem....or it might be an advantage !! measure time ??
I guess the best for plain signal strength logs would be to look for a
"beacon" in Russia in the 50 - 150kHz range. Maybe Alex has some ideas of
signals that plague his receiver but could be "music" to us further west.
I am beginning to wonder just how simple an LF converter could be to
convert 20kHz chunks of LF down to the soundcard inputs, with the
appropriate levels of sensitivity.
Cheers de Alan G3NYK
[email protected]
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