At Cumiana Italy 44.96N,7.42E run by Renato Romero IK1QFK:
Examining 9177Hz S/N and phase in 1 hour steps (278uHz)
transmission started around 21:20
21:30 6.2dB -102.3
22:30 6.1dB -159.4
23:00 5.3dB 155.1
23:30 4.1dB 172.9
00:00 6.4dB 151.8
00:30 6.4dB -173.8
01:00 4.4dB -174.5
01:30 6.2dB -174.0
02:00 8.9dB -165.6
02:30 8.1dB -161.3
03:00 6.8dB 151.3
03:30 9.8dB -178.6
transmission ended around 04:30
Undoubtedly a signal there. The steady phase tells us it is a
properly disciplined source, a spurious signal from an ordinary
xtal source would show lots of drift. A mains harmonic would
be invisible at this bandwidth (it would just add to background
noise as it drifted by).
So, is it W4DEX? A repeat test with a small frequency shift
would provide confirmation. S/N is about right given the
extra 1Mm beyond Todmorden. Frequency is exact which is
improbable otherwise. The signal vanishes after Dex switches
off. Signal not present before 21:30, therefore not a harmonic
of Renato's GPS timing system.
S/N is 13.7dB in this 4 hour spectrum:
It is the strongest signal in 23000 neighbouring bins.
With the above, and this one by DL4YHF from the 2nd,
we have two good candidate detections of W4DEX in Europe, awaiting
See Renato's website http://www.vlf.it/ for lots of articles
about VLF/ELF reception techniques.