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Since Friday 21:45, I have
been transmitting an unmodulated carrier on 8970.000. It is not GPS locked,
but controlled by a Rb standard which has been calibrated to better than about
0.05 ppb. The carrier has been on continuously with uninterrupted phase and
0.29 A into the home antenna (about 5 uW EMRP), and I intend to leave it on until 12 UT
today.
The purpose of this
experiment is to observe the 9 kHz diurnal propagation cycle across 180 km
to the DK7FC grabber, and compare to it to the pattern of the
long carrier from DJ8WX (8970.022) across 500 km. Both trace are mostly
well visible in Stefan's "6000" window, with some features worth
noting:
- For the 180 km path, generally the strongest
signals is seen during morning and afternoon periods, with a shallow
minimum around noon. For 500 km however, there is a proad maximum around
noon from 7 to 17 UT, coinciding with the daily QRN minimum.
- There appears to be a pronounced dip before
sunrise around 4:30 for DF6NM, whereas DJ8WX shows a broad minimum from
abot 2 to 5 UT.
- Both stations seem to be affected by a loss
of signal on some evenings after 18 UT. The signal
seems to drop out while the QRN is building up. This could be a real
propagation effect. But there may also be the possibility of
a receiver artifact, perhaps caused by the injected 10 kHz GPS
tone being affected by QRN. On the other hand, Stefan's Alpha
window shows perfect lock.
The DFCW signals in the screenshot are a
nice "G" sent by OE3GHB, an "NM" from here, and a local test by Stefan
from a PC nextdoors.
Markus
(DF6NM in Nuernberg JN59NK)
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