LF: Mystery VLF signals in Italy]

[Andre' Kesteloot]

Toni Bärtschi wrote:

> >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