[Fwd: LF: phantoms signals=Luxemburg Effect

[Andre' Kesteloot]

Johan Bodin wrote:

> Hello Rik and the LF group.
>
> Rik Strobbe wrote:
>
> > 1. Last night (22.15 UT) I noticed that the German carrier at 138kHz was
> > off air and also the phantom signals arround 137kHz that I hear all nights
> > were gone.
> > So these phantoms signals are 100% related to the 138kHz carrier, leaving 2
> > possibilities :
> >    - intermodulation in my RX
> >    - Luxemburg effect
> > Since I only hear these phantom signals at night and they do disapear when
> > I use an attenuator I'm quit sure that it is the famous Luxemburg effect.
> > At quiet evenings (low QRN) these phantom signals are often the limiting
> > factor at RX side.
>
> Did you identify the BC stations?
>
> I can also hear phantom signals here every night. I am sure it is the
> Luxembourg effect. I can often hear many BC stations at the same time
> on the 138.8 kHz carrier! The stations I hear are all located close to the
> line between the LF transmitter and my QTH. Also, they all transmit around
> 1.2 MHz. I can hear Radio Sweden on 138.8 kHz almost every night, their
> TX is on 1179 kHz. There is some kind of electron resonance (I think it is
> called cyclotron frequency) in the ionospere. The reflection/absorption
> properties of the D-layer is modulated by the AM of strong BC signals.
>
> I have noticed that the phantom audio signal has weaker high frequency
> components than the original audio on medium wave. It sounds as if the
> audio has passed through a lowpass filter. I guess it has something to do
> with a time constant in the ionosphere.
>
> 73, Johan SM6LKM