Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss
DSL interference on AM radio
118 views
Skip to first unread message
Bhairitu
Apr 20, 2012, 3:17:12 PM4/20/12
to
I have a kitchen AM/FM under the counter radio and since changing to
U-Verse there is a loud hiss on the AM stations even strong ones like
KGO (no interference on FM). Prior the regular AT&T DSL did not cause
such interference. The line runs up the opposite side of the wall from
the radio and I was thinking of replacing at least part of it with some
other cable. Any recommendations? The U-Verse tech suggested CAT5.
Incidentally a boombox radio a few feet away does not suffer the hiss
(but doesn't have push button tuning).
U-Verse there is a loud hiss on the AM stations even strong ones like
KGO (no interference on FM). Prior the regular AT&T DSL did not cause
such interference. The line runs up the opposite side of the wall from
the radio and I was thinking of replacing at least part of it with some
other cable. Any recommendations? The U-Verse tech suggested CAT5.
Incidentally a boombox radio a few feet away does not suffer the hiss
(but doesn't have push button tuning).
Jeff Liebermann
Apr 20, 2012, 5:02:52 PM4/20/12
to
On Fri, 20 Apr 2012 12:17:12 -0700, Bhairitu <nooz...@sbcglobal.net>
wrote:
Unplug the phone line from the house at the demarc (where the line
enters the splitter, protector, or terminal block). If the noise goes
away, it's probably the DSL. U-worse, also known as ADSL2+, goes all
the way up to 12MHz, while the older ADSL only went up to about
1.5Mhz. If it's still there when you unplug the line, look for
another source or switch to FM radio. Shielded CAT5 might help.
--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com je...@cruzio.com
# http://www.LearnByDestroying.com AE6KS
wrote:
enters the splitter, protector, or terminal block). If the noise goes
away, it's probably the DSL. U-worse, also known as ADSL2+, goes all
the way up to 12MHz, while the older ADSL only went up to about
1.5Mhz. If it's still there when you unplug the line, look for
another source or switch to FM radio. Shielded CAT5 might help.
--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com je...@cruzio.com
# http://www.LearnByDestroying.com AE6KS
David Kaye
Apr 20, 2012, 5:29:29 PM4/20/12
to
"Jeff Liebermann" <je...@cruzio.com> wrote
> Unplug the phone line from the house at the demarc (where the line
> enters the splitter, protector, or terminal block). If the noise goes
> away, it's probably the DSL.
Perhaps a 300pf ceramic capacitor rated over 150v across the DSL leads on
the subscriber side of the DSL? Should pass DSL freqs but shunt the RF.
> Unplug the phone line from the house at the demarc (where the line
> enters the splitter, protector, or terminal block). If the noise goes
> away, it's probably the DSL.
the subscriber side of the DSL? Should pass DSL freqs but shunt the RF.
Jeff Liebermann
Apr 20, 2012, 9:04:08 PM4/20/12
to
ADSL2+ frequency range. Anything you do to filter at the BCB, you
also end up filtering the ADSL2+ signals.
<http://upload.wikimedia.org/wikipedia/commons/8/8b/ADSL2_frequencies.png>
300PF at 1MHz is about 500 ohms reactance. That's not going to do
much for a 600 ohm system. Maybe 3dB down at 1MHz. At 1KHz audio
frequencies, it's more like 500 Kohms, which isn't going to do
anything.
According to theory, if the system is totally balanced, there won't be
any radiation. However, a bit of leakage from one line to ground or
to some other conductor, and it turns into a radiating antenna. Since
ADSL2+ needs bandwidth from 0.4 to 12MHz, filtering isn't going to do
anything useful.
Mike Durkin
Apr 20, 2012, 10:52:45 PM4/20/12
to
In article <6e14p7l94uigmis8n...@4ax.com>,
being repeated. Pretty sure ADSL2+ tops out at 2.2Mhz. VDSL1 goes
to 12Mhz, and VDSL2 goes to 30Mhz with profiles that utilitze 8, 12,
and 17Mhz. The 30Mhz profiles are mostly just used in MTU/MDU
environments and a lot of gear ommits them entirely.
Jeff Liebermann <je...@cruzio.com> wrote:
>Nope. The problem is that the BCB is right in the middle of the
>ADSL2+ frequency range. Anything you do to filter at the BCB, you
>also end up filtering the ADSL2+ signals.
><http://upload.wikimedia.org/wikipedia/commons/8/8b/ADSL2_frequencies.png>
I believe the 12Mhz top end shown for ADSL2+ is just incorrect information
>Nope. The problem is that the BCB is right in the middle of the
>ADSL2+ frequency range. Anything you do to filter at the BCB, you
>also end up filtering the ADSL2+ signals.
><http://upload.wikimedia.org/wikipedia/commons/8/8b/ADSL2_frequencies.png>
being repeated. Pretty sure ADSL2+ tops out at 2.2Mhz. VDSL1 goes
to 12Mhz, and VDSL2 goes to 30Mhz with profiles that utilitze 8, 12,
and 17Mhz. The 30Mhz profiles are mostly just used in MTU/MDU
environments and a lot of gear ommits them entirely.
Kevin McMurtrie
Apr 21, 2012, 2:00:51 AM4/21/12
to
In article <aDikr.1827$Jf7....@newsfe21.iad>,
In ideal conditions, a balanced DSL signal flows over two twisted wires
so that no signals radiate in or out. Sections of untwisted wires, a
filter installed incorrectly, or single-wire shorts can convert your DSL
into radio waves. That's bad for the radio and your DSL throughput.
The first thing I'd check is the indoor and outdoor wall outlets.
Sometimes you'll find a big rat's nest of wires smashed into the panel.
Pull your DSL pair out and re-twist them together.
--
I will not see posts from Google because I must filter them as spam
so that no signals radiate in or out. Sections of untwisted wires, a
filter installed incorrectly, or single-wire shorts can convert your DSL
into radio waves. That's bad for the radio and your DSL throughput.
The first thing I'd check is the indoor and outdoor wall outlets.
Sometimes you'll find a big rat's nest of wires smashed into the panel.
Pull your DSL pair out and re-twist them together.
--
I will not see posts from Google because I must filter them as spam
Jeff Liebermann
Apr 21, 2012, 4:21:57 AM4/21/12
to
On Sat, 21 Apr 2012 02:52:45 GMT, mdu...@rawbw.com (Mike Durkin)
wrote:
>In article <6e14p7l94uigmis8n...@4ax.com>,
>Jeff Liebermann <je...@cruzio.com> wrote:
>>Nope. The problem is that the BCB is right in the middle of the
>>ADSL2+ frequency range. Anything you do to filter at the BCB, you
>>also end up filtering the ADSL2+ signals.
>><http://upload.wikimedia.org/wikipedia/commons/8/8b/ADSL2_frequencies.png>
>I believe the 12Mhz top end shown for ADSL2+ is just incorrect information
>being repeated. Pretty sure ADSL2+ tops out at 2.2Mhz.
That's correct. I took the number off the above Wikipedia picture
without thinking about it. It should be 2.2MHz. Here's the same
picture, with the correct numbers:
<http://www.maxim-ic.com/app-notes/index.mvp/id/3638>
Even so, the BCB (broadcast band) is still in the middle of the ADSL
frequency range.
In the recent past, I've traced ham radio HF noise sources to
switching regulator wall wart power supplies and chargers. Some of
the little devils are really quite RF noisy. I would not be surprised
if that's the problem.
I've also found several RF noisy LED light "bulbs". While using less
power, the built in regulators on some of these LED lights is very
noisy. Oddly, it's only some LED lights, and not every LED light of
the same type. I have five lights, only two of which are noisy.
<http://www.youtube.com/watch?v=o8zMhjXcmoA>
(14 min) The tests shown cover 0.5-2.1MHz, which includes the AM
broadcast band. The noise maker shown at 10 minutes is exactly like
the LED lights that I'm using (which are noisy).
I tested my home ADSL line for various forms of RFI and heard nothing
on my antique Icom IC-735 transceiver. Same with a portable AM radio.
My phone wiring is mostly UTP CAT5, which doesn't radiate very much.
Some more details on what's happening behind the curtain:
<http://www.kitz.co.uk/adsl/adsl_technology.htm>
Sorry about the bad number and my thanks to those trying to keep me
honest.
>VDSL1 goes
>to 12Mhz, and VDSL2 goes to 30Mhz with profiles that utilitze 8, 12,
>and 17Mhz. The 30Mhz profiles are mostly just used in MTU/MDU
>environments and a lot of gear ommits them entirely.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
wrote:
>In article <6e14p7l94uigmis8n...@4ax.com>,
>Jeff Liebermann <je...@cruzio.com> wrote:
>>Nope. The problem is that the BCB is right in the middle of the
>>ADSL2+ frequency range. Anything you do to filter at the BCB, you
>>also end up filtering the ADSL2+ signals.
>><http://upload.wikimedia.org/wikipedia/commons/8/8b/ADSL2_frequencies.png>
>I believe the 12Mhz top end shown for ADSL2+ is just incorrect information
>being repeated. Pretty sure ADSL2+ tops out at 2.2Mhz.
without thinking about it. It should be 2.2MHz. Here's the same
picture, with the correct numbers:
<http://www.maxim-ic.com/app-notes/index.mvp/id/3638>
Even so, the BCB (broadcast band) is still in the middle of the ADSL
frequency range.
In the recent past, I've traced ham radio HF noise sources to
switching regulator wall wart power supplies and chargers. Some of
the little devils are really quite RF noisy. I would not be surprised
if that's the problem.
I've also found several RF noisy LED light "bulbs". While using less
power, the built in regulators on some of these LED lights is very
noisy. Oddly, it's only some LED lights, and not every LED light of
the same type. I have five lights, only two of which are noisy.
<http://www.youtube.com/watch?v=o8zMhjXcmoA>
(14 min) The tests shown cover 0.5-2.1MHz, which includes the AM
broadcast band. The noise maker shown at 10 minutes is exactly like
the LED lights that I'm using (which are noisy).
I tested my home ADSL line for various forms of RFI and heard nothing
on my antique Icom IC-735 transceiver. Same with a portable AM radio.
My phone wiring is mostly UTP CAT5, which doesn't radiate very much.
Some more details on what's happening behind the curtain:
<http://www.kitz.co.uk/adsl/adsl_technology.htm>
Sorry about the bad number and my thanks to those trying to keep me
honest.
>VDSL1 goes
>to 12Mhz, and VDSL2 goes to 30Mhz with profiles that utilitze 8, 12,
>and 17Mhz. The 30Mhz profiles are mostly just used in MTU/MDU
>environments and a lot of gear ommits them entirely.
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Bhairitu
Apr 21, 2012, 3:30:18 PM4/21/12
to
On 04/20/2012 02:02 PM, Jeff Liebermann wrote:
> On Fri, 20 Apr 2012 12:17:12 -0700, Bhairitu<nooz...@sbcglobal.net>
> wrote:
>
>> I have a kitchen AM/FM under the counter radio and since changing to
>> U-Verse there is a loud hiss on the AM stations even strong ones like
>> KGO (no interference on FM). Prior the regular AT&T DSL did not cause
>> such interference. The line runs up the opposite side of the wall from
>> the radio and I was thinking of replacing at least part of it with some
>> other cable. Any recommendations? The U-Verse tech suggested CAT5.
>> Incidentally a boombox radio a few feet away does not suffer the hiss
>> (but doesn't have push button tuning).
>
> Unplug the phone line from the house at the demarc (where the line
> enters the splitter, protector, or terminal block). If the noise goes
> away, it's probably the DSL. U-worse, also known as ADSL2+, goes all
> the way up to 12MHz, while the older ADSL only went up to about
> 1.5Mhz. If it's still there when you unplug the line, look for
> another source or switch to FM radio. Shielded CAT5 might help.
>
I took my small Coby AM tuned to KGO and followed it all the way out to
> On Fri, 20 Apr 2012 12:17:12 -0700, Bhairitu<nooz...@sbcglobal.net>
> wrote:
>
>> I have a kitchen AM/FM under the counter radio and since changing to
>> U-Verse there is a loud hiss on the AM stations even strong ones like
>> KGO (no interference on FM). Prior the regular AT&T DSL did not cause
>> such interference. The line runs up the opposite side of the wall from
>> the radio and I was thinking of replacing at least part of it with some
>> other cable. Any recommendations? The U-Verse tech suggested CAT5.
>> Incidentally a boombox radio a few feet away does not suffer the hiss
>> (but doesn't have push button tuning).
>
> Unplug the phone line from the house at the demarc (where the line
> enters the splitter, protector, or terminal block). If the noise goes
> away, it's probably the DSL. U-worse, also known as ADSL2+, goes all
> the way up to 12MHz, while the older ADSL only went up to about
> 1.5Mhz. If it's still there when you unplug the line, look for
> another source or switch to FM radio. Shielded CAT5 might help.
>
the AT&T cable coming off the pole with interference all the way. I
also know that whenever I get close to the CO up the street interference
can even get bad on stations like KGO. However I noted this morning
that 740 AM KCBS does not have interference on the kitchen radio so only
certain frequencies are effected. I may try shielded CAT5 but I don't
want to rewire the house.
Bhairitu
Apr 21, 2012, 3:34:49 PM4/21/12
to
in quite a while but the interference is even there before it goes to
the panel and even before the AT&T box. I was definitely going to
replace the panel as I have another one that would be better around here
but it hasn't been a high priority. Shielded CAT5 before the panel
though may help.
Roy
Apr 21, 2012, 3:45:48 PM4/21/12
to
Many years ago, I was able to get interference from the cable company
down to where it didn't bother me any more.
The FCC can also work on electric companies.
Jeff Liebermann
Apr 21, 2012, 5:37:00 PM4/21/12
to
On Sat, 21 Apr 2012 12:30:18 -0700, Bhairitu <nooz...@sbcglobal.net>
wrote:
Did you unplug the house wiring at the demarc when you tested the AT&T
cable to the pole? If you left the house plugged in, and there's an
imbalance in the line, it's going to radiate all along the cable,
including the line to the pole.
You'll get more interference on weaker stations because the AGC
(automagic gain control) reduces the receiver sensitivity on strong AM
stations.
wrote:
cable to the pole? If you left the house plugged in, and there's an
imbalance in the line, it's going to radiate all along the cable,
including the line to the pole.
You'll get more interference on weaker stations because the AGC
(automagic gain control) reduces the receiver sensitivity on strong AM
stations.
0 new messages