SV: LF: Signals and voices (138.9 kHz)

[André Kesteloot]

> From: Johan Bodin, SM6LKM
>
> I have reason to believe that the voice sidebands heard around the
> 138.9 kHz carrier actually *are* caused by the "Luxembourg effect".
> [...]
> The medium wave transmitter in Sölvesborg is transmitting on
> 1179 kHz with 600 kW.

Hi Johan,

As I mentioned in a previous message, the Proceedings of the 1962 AGARD
(NATO) meeting contained some interesting details of the Luxembourg
effect.  Experiments were conducted in 1959 and 1960 to create, at will, a
"Luxembourg effect". What follows is a summary of the relevant part of the
chapter.

**********************************
In Naples, a VHF transmitter, operating between 50 and 75 MHz was
connected to a yagi. Total radiated power was 80 Kilowatts. The yagi was
aimed at the sky, at a slight angle from the vertical, so that, as it hit
the ionosphere at a height of about 90 KM, the vertical at that point was
the town of Brusciano, about 16 kilometers away from Naples.

The VHF transmitter was pulse modulated. The duration of the pulses was
350 uSec.  While "on", the transmitter would be further modulated with a
frequency sweeping between 1.1 and 1.3 MHz, in order to cover what the
paper refers to as "the local gyrofrequency" of 1.2 MHz.

A further 9 kilometers away was located a HF transmitter, tunable anywhere
between 1.7 and 2.2 MHz, at Nola.  This HF transmitter transmitted only an
unmodulated carrier.

At Brusciano (the half-way point), the HF transmitter could be heard,
modulated at the pulse rate of the VHF transmitter.  The modulation depth
was highest when the modulation frequency of the VHF transmitter was
between 1.10 and 1.11 MHz .

The experiments were repeated in 1962, with an incident angle much lower
that the previous one, between Naples and the Navy base at Augusta (about
130 Kilometers)

The experimenters concluded that
1). V. A. Bailey was correct in predicting in 1938 that is was possible to
create an artificial aurora by means of an intense emission of RF at the
frequency of the local gyrofrequency.

2)  the Ionosphere then becomes a plasma with non-linear characteristics,
separating the low-frequency modulation from the carrier of a modulated
wave.
*******************

Note: it is interesting that the local gyrofrequency mentioned above is
close to that of  the Sölvesborg Tx mentioned by Johan Bodin, SM6LKM

Hope this helps

73
Andre Kesteloot N4ICK