I am going nuts.
We are using a 2.4GHz wireless video broadcaster in our home (Germany,
240V, 50Hz, PAL TV 25fps). It is based in the lower level and
transmits a satellite receiver output to the upper level TV room,
about 25ft away (3x 1ft stone walls in between).
The received video signal has a large regular interference, a
horizonal stripe (about 5% high, small vertical bands with colored
specks, almost white appearance) crawls fast through the picture,
accompanied by a chopping noise, about 8-10 chops per second. The
stripe scrolls fast through the picture, about 2-3 times per second,
downwards.
A classical interference. PAL operates at 25cycles per second, German
power at 50Hz, what does this tell about the interference spectrum/
freq?

Yes, we have a variety of other wireless devices in the house,
including a Fritz! WLAN, 2 2.4GHz phone bases (5 mobile phones),
several wireless weather stations, a Razr cell phone.
I pulled ALL plugs of all known wireless devices, unscrewed fuses
wherever needed, NADA! The noise remains, as strong as before.
I even put all wireless phones into a metal box and carried it out of
the building, still no change.
Meaning that all my wireless devices do NOT have any impact at all,
the other noise is the main problem. WHERE THE HELL IS IT COMING FROM?

The received video signal is rather weak, moving the receiver around
yields interesting spots of "almost" no noise (about 1ft apart).
Interesting to note: the noise gets typically more solid if the
overall picture is better and clear/strong. Meaning if I settle for a
grainy video, then the stripe is almost invisible (yet noticable in
the audio part as the mentioned fast 'chop chop chop' noise)

I am at the end of my wits. Cannot analyze freq sprectrum nor do I
have other tools handy to investigate. Am a left handed physicist, not
an electrical freak, hence my plead for support here!
What could cause this strong interference, a neighbor, the power line,
the antenna from the satellite/cable (even switched off the HF
amplifier for TV)?

What else should I try to isolate the problem? Cut the power line of
all my neighbors?

Thanks a bunch!
michael