Video Sender Interference

P

Peter Tonkin

Guest
Wondering if anyone might be able to tell me what might be interfering with
my 2.GHz video sender, receiver end connected to TVcard in my PC. Have had
it set up for about 2 years and working fine, all of a sudden I start
getting some signal absolutely obliterating the reception lasting up to 20
minutes sometimes as short as a second. The transmitter is located in the
lounge room and the receiver is in separate garage so the signal does travel
outside the confines of the house for a short distance (about 3 metres).

TIA
Pete
 
1) Microwave oven
2) PC WLAN cards
3) Bluetooth devices inc. mobiles
4) Someone else's video sender
5) wireless security systems

and probably many more. It's a big, busy band

-Andrew

"Peter Tonkin" <petertonkin@exemail.com.au> wrote in message
news:422d847c$0$27857$61c65585@un-2park-reader-01.sydney.pipenetworks.com.au...
Wondering if anyone might be able to tell me what might be interfering
with my 2.GHz video sender, receiver end connected to TVcard in my PC.
Have had it set up for about 2 years and working fine, all of a sudden I
start getting some signal absolutely obliterating the reception lasting up
to 20 minutes sometimes as short as a second. The transmitter is located
in the lounge room and the receiver is in separate garage so the signal
does travel outside the confines of the house for a short distance (about
3 metres).

TIA
Pete
 
"Peter Tonkin" <petertonkin@exemail.com.au> wrote in message
news:422d847c$0$27857$61c65585@un-2park-reader-01.sydney.pipenetworks.com.au...
Wondering if anyone might be able to tell me what might be interfering
with my 2.GHz video sender, receiver end connected to TVcard in my PC.
Have had it set up for about 2 years and working fine, all of a sudden I
start getting some signal absolutely obliterating the reception lasting up
to 20 minutes sometimes as short as a second. The transmitter is located
in the lounge room and the receiver is in separate garage so the signal
does travel outside the confines of the house for a short distance (about
3 metres).

TIA
Pete


Try changing the channel on the sender/receiver.
You might have a WIFI network nearby (neighbour).
Similarly your neighbour might also have put in a microwave towards your end
of the house <--- annoying one you can't do much about [I suffer from the
same problem...with my own microwave though].

I've only had much problems with the WIFI only when I have the laptop
directly inbetween the sender/receiver - which is rare, because often my
laptop is the source for the sender :)
 
Peter Tonkin wrote:
Wondering if anyone might be able to tell me what might be
interfering with my 2.GHz video sender, receiver end connected to
TVcard in my PC. Have had it set up for about 2 years and working
fine, all of a sudden I start getting some signal absolutely
obliterating the reception lasting up to 20 minutes sometimes as
short as a second. The transmitter is located in the lounge room and
the receiver is in separate garage so the signal does travel outside
the confines of the house for a short distance (about 3 metres).
Sounds like someone's got a dodgy microwave door :)

Or it could be WiFi, but I would have thought it'd be more consistent in
that case, unless they have a preferred couch in a bad position.

Or it could be a 2.4GHz cordless phone - the duration of interference
pattern matches phone calls better than other uses.

Basically, the 2.4GHz band is a bit of a free-for-all. You migt be able to
improve things by moving the stations around a bit, but if they have
omnidirectional antennas you might not have much luck.
 
Peter Tonkin wrote:
Wondering if anyone might be able to tell me what might be
interfering with
my 2.GHz video sender, receiver end connected to TVcard in my PC.
Have had
it set up for about 2 years and working fine, all of a sudden I start

getting some signal absolutely obliterating the reception lasting up
to 20
minutes sometimes as short as a second. The transmitter is located
in the
lounge room and the receiver is in separate garage so the signal does
travel
outside the confines of the house for a short distance (about 3
metres).

Perhaps someone next door just bought a DECT phone. I have a couple of
Uniden DECT phones that seem to chatter constantly, judging by the
lines on the 2.4GHz A/V sender I tried out. They went back the next
day, although in hindsight it was probably silly to even try them in a
suburban area - eventually someone is going to buy something that
transmits on 2.4GHz...

Have you tried connecting a monitor to the receiver (ie, no PC powered
on)?
 
The interference is worse than that from a microwave, had that problem
before.

Just remembered that I can hear the feedback thru the PC speakers with the
video sender on and the PC turned off.

Thanks again
Pete
<googlegroups@sensation.net.au> wrote in message
news:1110342118.436087.168800@l41g2000cwc.googlegroups.com...
Peter Tonkin wrote:
Wondering if anyone might be able to tell me what might be
interfering with
my 2.GHz video sender, receiver end connected to TVcard in my PC.
Have had
it set up for about 2 years and working fine, all of a sudden I start

getting some signal absolutely obliterating the reception lasting up
to 20
minutes sometimes as short as a second. The transmitter is located
in the
lounge room and the receiver is in separate garage so the signal does
travel
outside the confines of the house for a short distance (about 3
metres).

Perhaps someone next door just bought a DECT phone. I have a couple of
Uniden DECT phones that seem to chatter constantly, judging by the
lines on the 2.4GHz A/V sender I tried out. They went back the next
day, although in hindsight it was probably silly to even try them in a
suburban area - eventually someone is going to buy something that
transmits on 2.4GHz...

Have you tried connecting a monitor to the receiver (ie, no PC powered
on)?
 
"Peter Tonkin" <petertonkin@exemail.com.au> wrote in message
news:422d847c$0$27857$61c65585@un-2park-reader-01.sydney.pipenetworks.com.au...
Wondering if anyone might be able to tell me what might be interfering
with
my 2.GHz video sender, receiver end connected to TVcard in my PC. Have
had
it set up for about 2 years and working fine, all of a sudden I start
getting some signal absolutely obliterating the reception lasting up to 20
minutes sometimes as short as a second. The transmitter is located in the
lounge room and the receiver is in separate garage so the signal does
travel
outside the confines of the house for a short distance (about 3 metres).

TIA
Pete
Can you get hold of a spec-an? That way you can see what is happening ie
whether its a case of direct interference or a product of unwanted mixing.

Jason
 
Not much chance of getting a spec-analyser, but curious what you mean by
unwanted mixing.

TIA
Pete
"Jason James" <vellicet@bigpond.com> wrote in message
news:3998vfF5vn5nfU1@individual.net...
"Peter Tonkin" <petertonkin@exemail.com.au> wrote in message
news:422d847c$0$27857$61c65585@un-2park-reader-01.sydney.pipenetworks.com.au...
Wondering if anyone might be able to tell me what might be interfering
with
my 2.GHz video sender, receiver end connected to TVcard in my PC. Have
had
it set up for about 2 years and working fine, all of a sudden I start
getting some signal absolutely obliterating the reception lasting up to
20
minutes sometimes as short as a second. The transmitter is located in
the
lounge room and the receiver is in separate garage so the signal does
travel
outside the confines of the house for a short distance (about 3 metres).

TIA
Pete

Can you get hold of a spec-an? That way you can see what is happening ie
whether its a case of direct interference or a product of unwanted mixing.

Jason
 
"Peter Tonkin" <petertonkin@exemail.com.au> wrote in message
news:423048f2$0$27622$61c65585@un-2park-reader-02.sydney.pipenetworks.com.au...
Not much chance of getting a spec-analyser, but curious what you mean by
unwanted mixing.

TIA
Pete
The analyser will give you a picture of what signals are present in and on
either side of your link Rx's bandpass. I used to do RFI work at a busy
mountain top broadcast and comms site and as the field of RFI is not very
well documented, I had to learn most about it my self as I went along.

If you can place your SA in place of your Rx, any direct fundamental
interfering carriers can be checked against allocation records (supplied by
DOC and some private publications) for correct freq and in some cases if
relevant, mod type and index: eg 2 FM carriers adding will produce an
intermod which has combined mod twice the peak deviation. This wide spectral
occupancy can 'splash' into the bandpass of an adjacent Rx (freq-wise)


Mixing of 2 or more carriers can occur in the power-amp of a one or more of
the participating transmitters depending on how good their output filtering
is. At the site I used to work at, a rule was promulgated that all Txs had
to have at least one hi-Q resonator on their outputs.
The same thing can occur in a receiver if the carriers are high enough in
amplitude to get past the Rx's input filters and into the Rx's mixer at
sufficient level. Mixing can also occur in metal joints which are
corroded,..anything which presents as non-linear.

I haven't had experience with uW ovens and their role in producing RFI,..
and my work was in the VHF-UHF area.

If you think your link Rx is too wide and is not providing enough rejection
to adjacent carriers, you could try re-orientating the Tx and Rx so their
aerials are operating on a different axis,..though they are probably a
fairly wide beam.

Jason
 
Thanks Jason

Pete


"Jason James" <vellicet@bigpond.com> wrote in message
news:39bo3sF5he8vmU1@individual.net...
"Peter Tonkin" <petertonkin@exemail.com.au> wrote in message
news:423048f2$0$27622$61c65585@un-2park-reader-02.sydney.pipenetworks.com.au...
Not much chance of getting a spec-analyser, but curious what you mean by
unwanted mixing.

TIA
Pete

The analyser will give you a picture of what signals are present in and on
either side of your link Rx's bandpass. I used to do RFI work at a busy
mountain top broadcast and comms site and as the field of RFI is not very
well documented, I had to learn most about it my self as I went along.

If you can place your SA in place of your Rx, any direct fundamental
interfering carriers can be checked against allocation records (supplied
by
DOC and some private publications) for correct freq and in some cases if
relevant, mod type and index: eg 2 FM carriers adding will produce an
intermod which has combined mod twice the peak deviation. This wide
spectral
occupancy can 'splash' into the bandpass of an adjacent Rx (freq-wise)


Mixing of 2 or more carriers can occur in the power-amp of a one or more
of
the participating transmitters depending on how good their output
filtering
is. At the site I used to work at, a rule was promulgated that all Txs had
to have at least one hi-Q resonator on their outputs.
The same thing can occur in a receiver if the carriers are high enough in
amplitude to get past the Rx's input filters and into the Rx's mixer at
sufficient level. Mixing can also occur in metal joints which are
corroded,..anything which presents as non-linear.

I haven't had experience with uW ovens and their role in producing RFI,..
and my work was in the VHF-UHF area.

If you think your link Rx is too wide and is not providing enough
rejection
to adjacent carriers, you could try re-orientating the Tx and Rx so their
aerials are operating on a different axis,..though they are probably a
fairly wide beam.

Jason
 
"Peter Tonkin" <petertonkin@exemail.com.au> wrote in message
news:422ef160$0$27864$61c65585@un-2park-reader-01.sydney.pipenetworks.com.au
....
The interference is worse than that from a microwave, had that problem
before.

Just remembered that I can hear the feedback thru the PC speakers with the
video sender on and the PC turned off.
What about with the PC speaker's audio lead unplugged from the PC or any
other source?

WR
 
Hello John,

Since Peter mentioned this wide time span of 1 sec to 20 minutes there
is another source that might fit that pattern: A 2.4GHz cordless phone.
We have those, of the spread spectrum kind.

A 1 sec noise could be just a call, like ringing info transferred to the
phone. 20 mins could be if someone actually picks up and chats with
uncle Leroy for a while.

Regards, Joerg

http://www.analogconsultants.com
 
Thank for the replies so far.

Just a little more info, the problem stopped for about 6 weeks then came
back, it is also possible that the interference is not on the 2.4GHz band
but FM as (if I remember correctly) the audio is sent via FM. The video
sender receiver is connected to the AV in on my Tv card and the audio is
connected via the auxiliary on the sound card.
"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:972_d.11199$C47.1971@newssvr14.news.prodigy.com...
Hello John,

Since Peter mentioned this wide time span of 1 sec to 20 minutes there is
another source that might fit that pattern: A 2.4GHz cordless phone. We
have those, of the spread spectrum kind.

A 1 sec noise could be just a call, like ringing info transferred to the
phone. 20 mins could be if someone actually picks up and chats with uncle
Leroy for a while.

Regards, Joerg

http://www.analogconsultants.com
 
Got a bit carried away with the send button then, a little more info
inserted.


"Peter Tonkin" <petertonkin@exemail.com.au> wrote in message
news:42400f6c$0$27854$61c65585@un-2park-reader-01.sydney.pipenetworks.com.au...
Thank for the replies so far.

Just a little more info, the problem stopped for about 6 weeks then came
back, it is also possible that the interference is not on the 2.4GHz band
but FM as (if I remember correctly) the audio is sent via FM. The video
sender receiver is connected to the AV in on my Tv card and the audio is
connected via the auxiliary on the sound card.
While watching normal TV on the computer I can still hear the interference
if the auxiliary is not muted on the sound card.

TIA
Pete


"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:972_d.11199$C47.1971@newssvr14.news.prodigy.com...
Hello John,

Since Peter mentioned this wide time span of 1 sec to 20 minutes there is
another source that might fit that pattern: A 2.4GHz cordless phone. We
have those, of the spread spectrum kind.

A 1 sec noise could be just a call, like ringing info transferred to the
phone. 20 mins could be if someone actually picks up and chats with uncle
Leroy for a while.

Regards, Joerg

http://www.analogconsultants.com
 
Hello Peter,

It would probably make sense to keep a journal on these effects. That
helps identifying the cause. A 6-week break could, for example, be
linked to neighbors being on vacation and not using their phone or
whatever other offender.

Of course, this has got to be outside the US. We only get 2 weeks a year -:(

Regards, Joerg

http://www.analogconsultants.com
 

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