Wireless Network and Speaker Interference

I've been trying to attach an older (Win 98se era) laptop to a wireless
network (802.11b). The CardBus card installs properly, but I'm getting
a lot of fart noises from the built-in speakers.

Is there any way to eliminate that, short of physically removing the
speakers?

Grinder wrote:
I've been trying to attach an older (Win 98se era) laptop to a wireless
network (802.11b). The CardBus card installs properly, but I'm getting
a lot of fart noises from the built-in speakers.

Is there any way to eliminate that, short of physically removing the
speakers?

I notice that if I leave headphones plugged into the laptop, that the
interference (reasonably) is gone. Is there some sort of "null
headphone" that I could plug into the headphone jack to short circuit
the interference without having to leave a full set of headphones
dangling?

Grinder wrote:
Grinder wrote:
I've been trying to attach an older (Win 98se era) laptop to a
wireless network (802.11b). The CardBus card installs properly, but
I'm getting a lot of fart noises from the built-in speakers.

Is there any way to eliminate that, short of physically removing the
speakers?

I notice that if I leave headphones plugged into the laptop, that the
interference (reasonably) is gone. Is there some sort of "null
headphone" that I could plug into the headphone jack to short circuit
the interference without having to leave a full set of headphones dangling?

Radio Shack has audio cables, and one of those might fit the 1/8" stereo
jack. You can also buy just the plug part itself.

Paul

Paul wrote:
Grinder wrote:
Grinder wrote:
I've been trying to attach an older (Win 98se era) laptop to a
wireless network (802.11b). The CardBus card installs properly, but
I'm getting a lot of fart noises from the built-in speakers.

Is there any way to eliminate that, short of physically removing the
speakers?

I notice that if I leave headphones plugged into the laptop, that the
interference (reasonably) is gone. Is there some sort of "null
headphone" that I could plug into the headphone jack to short circuit
the interference without having to leave a full set of headphones
dangling?

Radio Shack has audio cables, and one of those might fit the 1/8" stereo
jack. You can also buy just the plug part itself.

Yeah, I cut one of those down and it doesn't look so bad. I was sort of
hoping for something more finished looking, but I can live with what I have.

I have since opened up the laptop and taken a look at the speakers. On
the front edge of laptop there's a mousepad, headphone and microphone
jacks, a half a dozen LEDs and about a dozen buttons. All of that stuff
is directly connected to a small circuit board that is attached to the
mainboard by a ribbon cable.

From the mainboard are 4 heavier gauge wires that run to the speakers.
They look to be left, right and a couple of ground wires. Is there
any way for me to add shielding to these components?

Grinder wrote:
Paul wrote:
Grinder wrote:
Grinder wrote:
I've been trying to attach an older (Win 98se era) laptop to a
wireless network (802.11b). The CardBus card installs properly, but
I'm getting a lot of fart noises from the built-in speakers.

Is there any way to eliminate that, short of physically removing the
speakers?

I notice that if I leave headphones plugged into the laptop, that the
interference (reasonably) is gone. Is there some sort of "null
headphone" that I could plug into the headphone jack to short circuit
the interference without having to leave a full set of headphones
dangling?

Radio Shack has audio cables, and one of those might fit the 1/8" stereo
jack. You can also buy just the plug part itself.

Yeah, I cut one of those down and it doesn't look so bad. I was sort of
hoping for something more finished looking, but I can live with what I
have.

I have since opened up the laptop and taken a look at the speakers. On
the front edge of laptop there's a mousepad, headphone and microphone
jacks, a half a dozen LEDs and about a dozen buttons. All of that stuff
is directly connected to a small circuit board that is attached to the
mainboard by a ribbon cable.

From the mainboard are 4 heavier gauge wires that run to the speakers.
They look to be left, right and a couple of ground wires. Is there any
way for me to add shielding to these components?

I'm not sure I believe the problem is with the speaker wires. The RF coupling
is probably into a sensitive signal with is an input to the audio chip.
Sometimes, muting items in the Mixer, as inputs, will stop the noises.

There are several ways to upset a sound chip.

1) A sound chip, when in playback, needs a steady diet of data. If
it doesn't get to DMA data in time, or an interrupt handler is slow,
sound distortion can occur. Sometimes a trivial hardware addition can
upset the bus or interrupt structure enough to disturb playback.

2) If there is no playback currently occurring, it is also possible
for the analog CD input, the aux input, mic in, line in, etc.,
to travel through the mixer and to the Line Out and the speakers.
Muting all the input paths can sometimes improve things. RF coupling
and diode rectification, in an input path, is what would make the noise.

(PDF page 43, the "sigma" symbol, shows all the inputs to the mixer.)
http://download.intel.com/support/mo...b/ac97_r23.pdf

3) "Farting" sounds can be caused by low frequency oscillation in
audio output amplifiers. For example, placing lower than a 50 ohm
load on an operational amplifier, will make the "farting" or
"motor boat" sound. But in this case, I don't see how adding a
wireless card, would place an actual electrical load on the
speaker wires.

HTH,
Paul

On Tue, 31 Jul 2007 21:52:05 -0400, Paul
wrote:

Grinder wrote:
Paul wrote:
Grinder wrote:
Grinder wrote:
I've been trying to attach an older (Win 98se era) laptop to a
wireless network (802.11b). The CardBus card installs properly, but
I'm getting a lot of fart noises from the built-in speakers.

Is there any way to eliminate that, short of physically removing the
speakers?

How creative do you want to get? You might just turn down
the speakers, or if there's space nearby on the case to do
it, put in a DPST switch that opens the positive lead to
each speaker. It needs be the positive instead of trying to
use a common ground through a SPST switch, or you could
instead use a DPDT switch and keep the speaker grounds
isolated until after the switch (between it and the
mainboar).




I notice that if I leave headphones plugged into the laptop, that the
interference (reasonably) is gone. Is there some sort of "null
headphone" that I could plug into the headphone jack to short circuit
the interference without having to leave a full set of headphones
dangling?

Radio Shack has audio cables, and one of those might fit the 1/8" stereo
jack. You can also buy just the plug part itself.

Yeah, I cut one of those down and it doesn't look so bad. I was sort of
hoping for something more finished looking, but I can live with what I
have.

How finished does it need be? The "plug" doesn't actually
have to be a headphone plug at all, just something of
roughly the same length and same diameter, and
non-conductive (at least not conductive across the output
pins & ground. For example a nylon flathead screw from the
hardware store.



I have since opened up the laptop and taken a look at the speakers. On
the front edge of laptop there's a mousepad, headphone and microphone
jacks, a half a dozen LEDs and about a dozen buttons. All of that stuff
is directly connected to a small circuit board that is attached to the
mainboard by a ribbon cable.

From the mainboard are 4 heavier gauge wires that run to the speakers.
They look to be left, right and a couple of ground wires. Is there any
way for me to add shielding to these components?

I'm not sure I believe the problem is with the speaker wires. The RF coupling
is probably into a sensitive signal with is an input to the audio chip.
Sometimes, muting items in the Mixer, as inputs, will stop the noises.

There are several ways to upset a sound chip.

1) A sound chip, when in playback, needs a steady diet of data. If
it doesn't get to DMA data in time, or an interrupt handler is slow,
sound distortion can occur. Sometimes a trivial hardware addition can
upset the bus or interrupt structure enough to disturb playback.

It seems less likely this would cause the motorboating
sound.



2) If there is no playback currently occurring, it is also possible
for the analog CD input, the aux input, mic in, line in, etc.,
to travel through the mixer and to the Line Out and the speakers.
Muting all the input paths can sometimes improve things. RF coupling
and diode rectification, in an input path, is what would make the noise.

(PDF page 43, the "sigma" symbol, shows all the inputs to the mixer.)
http://download.intel.com/support/mo...b/ac97_r23.pdf

3) "Farting" sounds can be caused by low frequency oscillation in
audio output amplifiers. For example, placing lower than a 50 ohm
load on an operational amplifier, will make the "farting" or
"motor boat" sound. But in this case, I don't see how adding a
wireless card, would place an actual electrical load on the
speaker wires.

HTH,
Paul

Agreed, anything picked up by the speaker leads won't
reduce the SNR by much.

I'm wondering if the notebook just has poor power filter
circuitry and so the addition of the card produces the
oscillation from dirtying up the power rail too much. A few
dozen pF cap across the +- analog amp stage imputs might
help (hard to say how integrated an old notebook is), or at
least tacked down across the power rails immediately
adjacent to the chip, though I'd have thought it already had
this decoupling.

Paul wrote:
Grinder wrote:
Paul wrote:
Grinder wrote:
Grinder wrote:
I've been trying to attach an older (Win 98se era) laptop to a
wireless network (802.11b). The CardBus card installs properly,
but I'm getting a lot of fart noises from the built-in speakers.

Is there any way to eliminate that, short of physically removing
the speakers?

I notice that if I leave headphones plugged into the laptop, that
the interference (reasonably) is gone. Is there some sort of "null
headphone" that I could plug into the headphone jack to short
circuit the interference without having to leave a full set of
headphones dangling?

Radio Shack has audio cables, and one of those might fit the 1/8" stereo
jack. You can also buy just the plug part itself.

Yeah, I cut one of those down and it doesn't look so bad. I was sort
of hoping for something more finished looking, but I can live with
what I have.

I have since opened up the laptop and taken a look at the speakers.
On the front edge of laptop there's a mousepad, headphone and
microphone jacks, a half a dozen LEDs and about a dozen buttons. All
of that stuff is directly connected to a small circuit board that is
attached to the mainboard by a ribbon cable.

From the mainboard are 4 heavier gauge wires that run to the
speakers. They look to be left, right and a couple of ground wires.
Is there any way for me to add shielding to these components?

I'm not sure I believe the problem is with the speaker wires. The RF
coupling
is probably into a sensitive signal with is an input to the audio chip.
Sometimes, muting items in the Mixer, as inputs, will stop the noises.

In this case, muting seems to have no effect on the burps at all.

There are several ways to upset a sound chip.

1) A sound chip, when in playback, needs a steady diet of data. If
it doesn't get to DMA data in time, or an interrupt handler is slow,
sound distortion can occur. Sometimes a trivial hardware addition can
upset the bus or interrupt structure enough to disturb playback.

2) If there is no playback currently occurring, it is also possible
for the analog CD input, the aux input, mic in, line in, etc.,
to travel through the mixer and to the Line Out and the speakers.
Muting all the input paths can sometimes improve things. RF coupling
and diode rectification, in an input path, is what would make the noise.

(PDF page 43, the "sigma" symbol, shows all the inputs to the mixer.)
http://download.intel.com/support/mo...b/ac97_r23.pdf

3) "Farting" sounds can be caused by low frequency oscillation in
audio output amplifiers. For example, placing lower than a 50 ohm
load on an operational amplifier, will make the "farting" or
"motor boat" sound. But in this case, I don't see how adding a
wireless card, would place an actual electrical load on the
speaker wires.

The noises are very strongly correlated to activity on the wireless
connection. At startup, when the card is looking for connections I get
the aforementioned flatulence in bursts every 10 seconds or so. Once I
have established a connection, I get shorter static bursts while loading
web pages. If the web pages is already in the cache--no static. Also,
if I turn on the radio on the card, all the interference goes completely
away.

Grinder wrote:

I've been trying to attach an older (Win 98se era) laptop to a wireless
network (802.11b). The CardBus card installs properly, but I'm getting
a lot of fart noises from the built-in speakers.


Networking

http://www.howstuffworks.com/home-network.htm
http://www.practicallynetworked.com/sharing/
http://www.annoyances.org/exec/show/category04
http://www.microsoft.com/windowsxp/u...g/default.mspx
http://compnetworking.about.com/od/w...Windows_XP.htm
http://support.microsoft.com/?kbid=813936
http://www.onecomputerguy.com/networking/xp_network.htm
http://www.microsoft.com/windowsxp/u...d/default.mspx




--
http://www.bootdisk.com/

Grinder wrote:


The noises are very strongly correlated to activity on the wireless
connection. At startup, when the card is looking for connections I get
the aforementioned flatulence in bursts every 10 seconds or so. Once I
have established a connection, I get shorter static bursts while loading
web pages. If the web pages is already in the cache--no static. Also,
if I turn on the radio on the card, all the interference goes completely
away.

Well, try playing with the mixer first. Mute some inputs and see if it
stops.

A remote possibility, is the place where the Wireless device draws power,
is near to where the sound chip has its three pin linear regulator. Some
motherboards provide a separate regulator for the sound chip, to try to
remove noise on the power rail. But I've been told, that spectrally,
a linear is not really good for doing that kind of cleanup. High frequency
noise might get passed through.

And if the Wireless device drew so much power, that the linear regulator
dropped out, that would also be a good reason for some farts.

You still didn't mention whether a sound file was playing at the time.
If the sound chip is not being used, and yet there are farts, then
at least we know it isn't a problem with DMA data getting there in time.

Paul

Paul wrote:
Grinder wrote:


The noises are very strongly correlated to activity on the wireless
connection. At startup, when the card is looking for connections I
get the aforementioned flatulence in bursts every 10 seconds or so.
Once I have established a connection, I get shorter static bursts
while loading web pages. If the web pages is already in the cache--no
static. Also, if I turn on the radio on the card, all the
interference goes completely away.

Well, try playing with the mixer first. Mute some inputs and see if it
stops.

It doesn't.

A remote possibility, is the place where the Wireless device draws power,
is near to where the sound chip has its three pin linear regulator. Some
motherboards provide a separate regulator for the sound chip, to try to
remove noise on the power rail. But I've been told, that spectrally,
a linear is not really good for doing that kind of cleanup. High frequency
noise might get passed through.

And if the Wireless device drew so much power, that the linear regulator
dropped out, that would also be a good reason for some farts.

You still didn't mention whether a sound file was playing at the time.

No, no other output is necessary. The interference appears (apparently)
unaffected by any intentional signal on the line.

If the sound chip is not being used, and yet there are farts, then
at least we know it isn't a problem with DMA data getting there in time.

DMA = Direct Memory Access?