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Re: QRM ON 2.4 GIG



Luc wrote:

I just copy pulsating  QRM when operating on AO-40 today. It was a local
source
no one else seems to copy this pulsating QRM. When listening the evening tv
newscast about 4 TV satellite mobil truck unit where in operation about 2
miles from
my QTH covering a judicial hearing.

Is these satellite feeds can be the source of my QRM i never get this type
of
interference before and its not the noise made be 2.4 gig phone?


Wayne replies:

I also get pulsing 2.4 GHz QRM at my QTH.  It is a strong pulse, about 1
pulse per second.  Here, it is usually strongest to the southwest, but I can
hear it no matter where my dish is pointed.  It does not seem to be there
all the time, but it is there most of the time.  The noise blanker helps,
but if I point to the southwest, the pulses will be several S-units stronger
than AO40 when the noise blanker is off.  And the pulses will be about the
same strength as AO40 with the noise blanker on.  When the pulses are loud,
I have to switch the radio to AFC-fast, which raises my overall noise level.

What terrestrial systems generate this kind of pulse?  Is it cordless
phones, wireless networks, or something else?  Do terrestrial 2.4 GHz
signals reflect from local objects?  I'm surprised that I can hear the pulse
no matter where I point my dish.  My dish has a G3RUH patch feed with
minimal side lobes.

It seems like 2400 MHz is becoming a "trash" band in the industrialized
world.  With unlicensed QRM and tree absorption, it's definitely not always
the ideal satellite downlink band.

Wayne Estes W9AE
Mundelein, IL, USA


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