From HB9ASB, JN36pt
I've never seen a response to Marcos query about the signal on 1025 Hz.
Here a possible explanation:
Of course I can see and hear the signal, like many others in the VLF/ULF
range, at my QTH.
They are coming over the mains but I can receive them also fro the air
with my 136 kHz aerial and detect them with my receiver and the
soundcard and spectrogram. The sources - at least here in Switzerland -
are well known. The signals are generated by our power stations and feed
into the mains to control street lamps, electricity counters in the
households (different day/night charges for the kWh) and other devices.
Here they are using thyristor or motor-generators with 60kw/22kV
connected via a serial LC to the medium voltage grid. The rectangular
pulses with 600ms intervals are coming in packets with 6 bits (including
a startbit) Different frequencies from 200Hz to 2kHz are in use. The
durations of these control signal emissions are normally between 10s and
100s and the time depends on the local Power Company. The system exists
since 1950 and is known under RSS (Rundsteuersignale).
The signal which switches my day/night charge at 21:00 UT and 05:00 UT
is so strong that I can hear it trough the loudspeaker of some old radio
receivers (especially tube type, produced before 1950) or even directly
out of some transformers!
May be, this is an explanation for the mystery signal in Italy on 1025
Hz.
73 de Toni
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