HELP: unique 2.4GHz video xmitter interference, what causes it?

[[email protected]]

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

 

[Adrian C]

A classical interference. PAL operates at 25cycles per second, German
power at 50Hz, what does this tell about the interference spectrum/
freq?

If you are using SCART, it's probably the internal tuner output from
your TV crossmodulating with the output from the sender receiver box.
Open up the SCART lead at the TV end and cut pin 19 (composite video
out). Or you may be able to switch this output off in a setup menu.

For a quick check before you do any of this - remove the aerial lead
from the TV. What happens?

 

[hr(bob) [email protected]]

If you are using SCART, it's probably the internal tuner output from
your TV crossmodulating with the output from the sender receiver box.
Open up the SCART lead at the TV end and cut pin 19 (composite video
out). Or you may be able to switch this output off in a setup menu.

For a quick check before you do any of this - remove the aerial lead
from the TV. What happens?

What about a microwave oven????

Bob Hofmann

 

[jakdedert]

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

Thanks a bunch!
michael

Sounds suspiciously like what my WiFi router does to my 2.4gig video
link. If you have a laptop with wifi, try checking for a signal in your
area...or ask a friend to bring over his laptop, if not.

jak

 

[Arfa Daily]

Sounds suspiciously like what my WiFi router does to my 2.4gig video link.
If you have a laptop with wifi, try checking for a signal in your
area...or ask a friend to bring over his laptop, if not.

jak

Could well be from a neighbour's WiFi. As well as my own, I can see three
other networks on my machines, one of which is stronger at one of my
locations, than my own network ! You could try rotating a large saucepan lid
around the video link receiver to see if the interference is minimised at
any point. That will then tell you the direction that it's getting in from.

Arfa

 

[Sjouke Burry]

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,

You are the lucky reciever of WIFI data blocks, if possible,
select the highest possible frequency you can get out of
your transmitter.
Been there, done that and solved it, because few people bother
to switch their WIFI to the high frequency channels.

 

[[email protected]]

What about a microwave oven????

Bob Hofmann

I bet you have an XBOX360? Their wireless radio in the box that communicates
with the controllers cuases massive interference within the2.4ghzrange.

What i dont get is why doesnt the FCC get after Microsoft on this one????

http://www.itwire.com/content/view/15821/1103/

http://www.gamespot.com/news/6136388.html

<http://www.joystiq.
com/2007/12/15/strange-xbox-360-signal-might-affect-wireless-lans/>- Zitierten Text ausblenden -

- Zitierten Text anzeigen -[/QUOTE]

Actually I DO NOT have an XBOX 8-( - and I don't miss it
And remember that I unplugged all devices and also pulled breakers
where needed? I literally sat in the dark with only the TV sets, Sat
receiver and xmitter working.

But I DO have success, sort of:
the transmitter allows to select 4 different broadcast channels, and
in one (D, the highest?) I noticed that the wide speckled and running
bar disappeared. It was replaced by 2 very narrow and absolutely
static ones! That was actually good news, as it was a DIFFERENT
interference, one I quickly identified as being from my own wireless
base station, located in the same room as the 2.4GHz receiver. That
one can be unplugged anytime; also I am considering to disable/cut the
transmitter or antenna - the base is not actively used, it only serves
as a charger for one cordless phone. It produces a very sharp, whitish
bar, in synch with the receiver for some reason (overtone or fraction
of the xmit frequency I suppose?), no audio interference noticable.
I am quite convinced that the other broad noise is indeed from a
neighbor's WiFi/WLAN system. What is baffling is that the plentitude
of my own wireless devices (with the exception of the one phone base
in the same room) have absolutely no impact on the xmitter/receiver
signal, and this bastard HAS, from 100ft away, through several 1foot
mason walls.
Anyways - thanks for the ideas, hints and suggestions, highly
appreciated!
michael

 

[Gary]

As Bob mentions, this is most likely to be caused by a microwave oven,
especially if it continues for a few minutes then stops completely. There's
nothing you can do except change the channel used for your video sender to
try and minimise it, use more directional aerials, or use a video sender
that uses a different band.

Regards,
Gary