a little OT: radio interference filter?

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a little OT: radio interference filter?

biggus
There are a couple of HD radio towers near my house and the signal often comes though the speaker MH uses to announce things to the house.  We already have filters on our phone lines and they work great, even though we practically had to _beg_ Comcast for one for the second line.  Has anyone else had this kind of interference issue?  If so, would a phone-line filter like the ones we have help? Also is it the speaker wire or the sound card that's picking up the signal?  This would tell me where to put the filter.

This interference could also be causing some of my X10-controlled  lights to switch on by themselves.

Thanks,
Mike


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Re: a little OT: radio interference filter?

Jim Serack
The radio interference levels would have to be extremely high to directly
affect X10 protocol or the wires between the amplifier and the speakers. In
both cases I would look at the input to something that could amplify the
radio noise - so a wireless X10 receiver could be affected enough to create
a strong X10 powerline signal that was not intended. (One could put a ground
plate between the X10RF receiver and the transmitting antennas to see if
that is the problem - e.g. a grounded cookie sheet). On the audio side the
most likely noise coupling would be between the sound card and whatever you
are using as an amplifier - this should be a shielded cable grounded at one
point (you should also read up on ground loops - grounding in two places can
make a very good antenna - eg both the pc and the amplifier have grounded
cases, and a ground cable between them = loop).  More remote possibilities
are; if you have input lines to the sound card (line in, microphone in, or
inside the pc the audio from the CD player to the sound card) they could
pickup and then feed through (in software) or as hardware cross talk. If you
remove them and it goes away then you need to check the grounding and
shielding. If the PC case is not metal (and grounded), or has the cover off,
or is plastic and the internal "paint" is not grounded that could make the
actual sound card susceptible to the noise - but it is the least likely.

Finally - if this something that is a recent change you might want to raise
a concern with the operator of the transmitter, or the FCC. Sometimes they
mess up the installation, or omit ground planes up on the tower and they
don't know they are radiating directly down into the community - it would be
worth a shot if it's a recent change. (They would be interested in both
keeping the peace with the neighbors, but also getting their value out of
their transmit levels - so that it goes somewhere useful).

Good Luck,
Jim

-----Original Message-----
From: storemike [mailto:[hidden email]]
Sent: March 19, 2009 3:51 PM
To: [hidden email]
Subject: [mh] a little OT: radio interference filter?

There are a couple of HD radio towers near my house and the signal often
comes though the speaker MH uses to announce things to the house.  We
already have filters on our phone lines and they work great, even though we
practically had to _beg_ Comcast for one for the second line.  Has anyone
else had this kind of interference issue?  If so, would a phone-line filter
like the ones we have help? Also is it the speaker wire or the sound card
that's picking up the signal?  This would tell me where to put the filter.

This interference could also be causing some of my X10-controlled  lights to
switch on by themselves.

Thanks,
Mike


----------------------------------------------------------------------------
--
Apps built with the Adobe(R) Flex(R) framework and Flex Builder(TM) are
powering Web 2.0 with engaging, cross-platform capabilities. Quickly and
easily build your RIAs with Flex Builder, the Eclipse(TM)based development
software that enables intelligent coding and step-through debugging.
Download the free 60 day trial. http://p.sf.net/sfu/www-adobe-com
________________________________________________________
To unsubscribe from this list, go to:
http://sourceforge.net/mail/?group_id=1365



------------------------------------------------------------------------------
Apps built with the Adobe(R) Flex(R) framework and Flex Builder(TM) are
powering Web 2.0 with engaging, cross-platform capabilities. Quickly and
easily build your RIAs with Flex Builder, the Eclipse(TM)based development
software that enables intelligent coding and step-through debugging.
Download the free 60 day trial. http://p.sf.net/sfu/www-adobe-com
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Re: a little OT: radio interference filter?

JimMH

Mike,

It would help if you describe your setup fully.  Are you using amplified speakers?  If so, the wiring to them could be picking up the RF.  If not that is unlikely.  To test connect unamplified speakers or headphones to the soundcard and see if you hear it then.  If so it is getting into the soundcard or to an input to the soundcard.  If you hear what is said into the microphone on the speakers then you should be able to change your audio mixer settings to turn off the path from mike to speakers to eliminate that - it will eliminate the noise if it is picked up on the mike input.

If you have amplified speakers and you don't hear it with unamplified speakers/headphones it is getting into the speaker amplifier.  Try the speakers disconnected from the sound card.  If you hear it then the speakers are the problem.  You could try a small capacitor or a ferrite bead on the input lines near the speakers.  You also might try changing the length of the wires.  But it may be getting into the amplifier on other than the input lines.  

You need to do some experimenting to determine where the signal is getting in before you can know how to fix it.

Jim

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Re: a little OT: radio interference filter?

biggus
In reply to this post by Jim Serack
Thanks Jims,

the speakers are amplified.  I'll try the headphones test to see if I hear it then.  

I didn't really think that the HD radio interference could be bonking my X10 signals, but I figured that the someone on this list could set me straight either way.  That's why I like this group.  

The HD towers were there when I moved in and we experienced the interference immediately on most everything: guitar amps, self-amplified studio monitors (hookled to my studio PC via a pre-amp), amplified PC speakers.  The standard non-amplified speakers you used to get with a new PC didn't seem to pick it up, neither does my home theater system - and the rear speakers have at least 20 feet of wriring to each.

Thanks again.  I'll see if I can get to this this weekend and will post my findings.

Sincerely,
Mike

--- In [hidden email], "Jim Serack" <jserack@...> wrote:

>
> The radio interference levels would have to be extremely high to directly
> affect X10 protocol or the wires between the amplifier and the speakers. In
> both cases I would look at the input to something that could amplify the
> radio noise - so a wireless X10 receiver could be affected enough to create
> a strong X10 powerline signal that was not intended. (One could put a ground
> plate between the X10RF receiver and the transmitting antennas to see if
> that is the problem - e.g. a grounded cookie sheet). On the audio side the
> most likely noise coupling would be between the sound card and whatever you
> are using as an amplifier - this should be a shielded cable grounded at one
> point (you should also read up on ground loops - grounding in two places can
> make a very good antenna - eg both the pc and the amplifier have grounded
> cases, and a ground cable between them = loop).  More remote possibilities
> are; if you have input lines to the sound card (line in, microphone in, or
> inside the pc the audio from the CD player to the sound card) they could
> pickup and then feed through (in software) or as hardware cross talk. If you
> remove them and it goes away then you need to check the grounding and
> shielding. If the PC case is not metal (and grounded), or has the cover off,
> or is plastic and the internal "paint" is not grounded that could make the
> actual sound card susceptible to the noise - but it is the least likely.
>
> Finally - if this something that is a recent change you might want to raise
> a concern with the operator of the transmitter, or the FCC. Sometimes they
> mess up the installation, or omit ground planes up on the tower and they
> don't know they are radiating directly down into the community - it would be
> worth a shot if it's a recent change. (They would be interested in both
> keeping the peace with the neighbors, but also getting their value out of
> their transmit levels - so that it goes somewhere useful).
>
> Good Luck,
> Jim
>
> -----Original Message-----
> From: storemike [mailto:storemike@...]
> Sent: March 19, 2009 3:51 PM
> To: misterhouse-users@...
> Subject: [mh] a little OT: radio interference filter?
>
> There are a couple of HD radio towers near my house and the signal often
> comes though the speaker MH uses to announce things to the house.  We
> already have filters on our phone lines and they work great, even though we
> practically had to _beg_ Comcast for one for the second line.  Has anyone
> else had this kind of interference issue?  If so, would a phone-line filter
> like the ones we have help? Also is it the speaker wire or the sound card
> that's picking up the signal?  This would tell me where to put the filter.
>
> This interference could also be causing some of my X10-controlled  lights to
> switch on by themselves.
>
> Thanks,
> Mike
>
>
> ----------------------------------------------------------------------------
> --
> Apps built with the Adobe(R) Flex(R) framework and Flex Builder(TM) are
> powering Web 2.0 with engaging, cross-platform capabilities. Quickly and
> easily build your RIAs with Flex Builder, the Eclipse(TM)based development
> software that enables intelligent coding and step-through debugging.
> Download the free 60 day trial. http://p.sf.net/sfu/www-adobe-com
> ________________________________________________________
> To unsubscribe from this list, go to:
> http://sourceforge.net/mail/?group_id=1365
>
>
>
> ------------------------------------------------------------------------------
> Apps built with the Adobe(R) Flex(R) framework and Flex Builder(TM) are
> powering Web 2.0 with engaging, cross-platform capabilities. Quickly and
> easily build your RIAs with Flex Builder, the Eclipse(TM)based development
> software that enables intelligent coding and step-through debugging.
> Download the free 60 day trial. http://p.sf.net/sfu/www-adobe-com
> ________________________________________________________
> To unsubscribe from this list, go to: http://sourceforge.net/mail/?group_id=1365
>



------------------------------------------------------------------------------
Apps built with the Adobe(R) Flex(R) framework and Flex Builder(TM) are
powering Web 2.0 with engaging, cross-platform capabilities. Quickly and
easily build your RIAs with Flex Builder, the Eclipse(TM)based development
software that enables intelligent coding and step-through debugging.
Download the free 60 day trial. http://p.sf.net/sfu/www-adobe-com
________________________________________________________
To unsubscribe from this list, go to: http://sourceforge.net/mail/?group_id=1365