Gaps in tones on ADSL router - question

I'm currently using a BT Voyager 2110 router, picked up at a car boot
sale for 50p.

This is quite configurable and works with the DMT utility:

http://dmt.mhilfe.de/

Out of the box, the modem synced at ~13500 kbps. I've been
experimenting with the telnet interface and the adslctl command to eke a
bit more out of it, working to get a target SNR of 3.1dB. Any lower and
the number of errors becomes too large.

This is the result:

http://jasper.org.uk/dmt.jpg

a 17724 kbps sync with a 3.1dB SNR margin.

There are these gaps in the tones:

Gap1 1108kHz - 1113kHz (Tone 257)
Gap2 1479kHz - 1501kHz (Tone 343 - Tone 347)
Gap3 1548kHz - 1552kHz (Tone 359)

Q: what is the cause of those gaps? Presumably interference of some
kind? Is there anything I can do about it?

--
(\_/)
(='.'=)
(")_(")

Mike Tomlinson wrote:
> I'm currently using a BT Voyager 2110 router, picked up at a car boot
> sale for 50p.
>
> This is quite configurable and works with the DMT utility:
>
> http://dmt.mhilfe.de/
>
> Out of the box, the modem synced at ~13500 kbps. I've been
> experimenting with the telnet interface and the adslctl command to eke a
> bit more out of it, working to get a target SNR of 3.1dB. Any lower and
> the number of errors becomes too large.
>
> This is the result:
>
> http://jasper.org.uk/dmt.jpg
>
> a 17724 kbps sync with a 3.1dB SNR margin.
>
> There are these gaps in the tones:
>
> Gap1 1108kHz - 1113kHz (Tone 257)
> Gap2 1479kHz - 1501kHz (Tone 343 - Tone 347)
> Gap3 1548kHz - 1552kHz (Tone 359)
>
> Q: what is the cause of those gaps? Presumably interference of some
> kind?

YES

Is there anything I can do about it?
>

Bomb Droitwich?

On 14/12/2011 08:48, The Natural Philosopher wrote:
> Mike Tomlinson wrote:
>> I'm currently using a BT Voyager 2110 router, picked up at a car boot
>> sale for 50p.
>>
>> This is quite configurable and works with the DMT utility:
>>
>> http://dmt.mhilfe.de/
>>
>> Out of the box, the modem synced at ~13500 kbps. I've been
>> experimenting with the telnet interface and the adslctl command to eke a
>> bit more out of it, working to get a target SNR of 3.1dB. Any lower and
>> the number of errors becomes too large.
>>
>> This is the result:
>>
>> http://jasper.org.uk/dmt.jpg
>>
>> a 17724 kbps sync with a 3.1dB SNR margin.
>>
>> There are these gaps in the tones:
>>
>> Gap1 1108kHz - 1113kHz (Tone 257)
>> Gap2 1479kHz - 1501kHz (Tone 343 - Tone 347)
>> Gap3 1548kHz - 1552kHz (Tone 359)
>>
>> Q: what is the cause of those gaps? Presumably interference of some
>> kind?
>
> YES
>
> Is there anything I can do about it?
>>
>
> Bomb Droitwich?
>

Yeah they've got it coming to them those damn Droitwichites.

In article <jc9ntd$gqt$(E-Mail Removed)>, The Natural Philosopher
<(E-Mail Removed)> writes

Gap1 1108kHz - 1113kHz
Gap2 1479kHz - 1501kHz
Gap3 1548kHz - 1552kHz

>YES

I was hoping for a bit more than that, such as "interference on 1108kHz
is caused by ham radio operators/sunspots/MI5/gamma rays/little green
men from planet Zarg (delete as appropriate)"

>Bomb Droitwich?

What's Droitwich done to you? :-)

--
(\__/)
(='.'=)
(")_(")

Mike Tomlinson wrote:
> In article <jc9ntd$gqt$(E-Mail Removed)>, The Natural Philosopher
> <(E-Mail Removed)> writes
>
> Gap1 1108kHz - 1113kHz
> Gap2 1479kHz - 1501kHz
> Gap3 1548kHz - 1552kHz
>
>> YES
>
> I was hoping for a bit more than that, such as "interference on 1108kHz
> is caused by ham radio operators/sunspots/MI5/gamma rays/little green
> men from planet Zarg (delete as appropriate)"
>
>> Bomb Droitwich?
>
> What's Droitwich done to you? :-)
>
Its what its done to you..

"Mike Tomlinson" <(E-Mail Removed)> wrote in message
news:PnwAd$(E-Mail Removed)...
>
> I'm currently using a BT Voyager 2110 router, picked up at a car boot
> sale for 50p.
>
> This is quite configurable and works with the DMT utility:
>
> http://dmt.mhilfe.de/
>
> Out of the box, the modem synced at ~13500 kbps. I've been
> experimenting with the telnet interface and the adslctl command to eke a
> bit more out of it, working to get a target SNR of 3.1dB. Any lower and
> the number of errors becomes too large.
>
> This is the result:
>
> http://jasper.org.uk/dmt.jpg
>
> a 17724 kbps sync with a 3.1dB SNR margin.
>
> There are these gaps in the tones:
>
> Gap1 1108kHz - 1113kHz (Tone 257)
> Gap2 1479kHz - 1501kHz (Tone 343 - Tone 347)
> Gap3 1548kHz - 1552kHz (Tone 359)
>
> Q: what is the cause of those gaps? Presumably interference of some
> kind? Is there anything I can do about it?
>
> --
> (\_/)
> (='.'=)
> (")_(")

30 Hz-4 kHz, voice.
4-25 kHz, unused guard band.
25-138 kHz, 25 upstream bins (7-31).
138-1104 kHz, 224 downstream bins (32-255).

Bins above 1108Khz would seem out of band for plain vanilla adsl anyway ?

Dave

On Wed, 14 Dec 2011 09:49:14 +0000, Mike Tomlinson <(E-Mail Removed)>
wrote in <WT+(E-Mail Removed)>:

>In article <jc9ntd$gqt$(E-Mail Removed)>, The Natural Philosopher
><(E-Mail Removed)> writes
>
>Gap1 1108kHz - 1113kHz
>Gap2 1479kHz - 1501kHz
>Gap3 1548kHz - 1552kHz
>
>>YES
>
>I was hoping for a bit more than that, such as "interference on 1108kHz
>is caused by ham radio operators/sunspots/MI5/gamma rays/little green
>men from planet Zarg (delete as appropriate)"
>
>>Bomb Droitwich?
>
>What's Droitwich done to you? :-)

What had Slough ever done to John Betjeman?
(<http://www-cdr.stanford.edu/intuition/Slough.html>)

Droitwich is home of a super-powerful transmitter that pumps out Radio 4
long wave with enough humungawatts to reach not only the whole of the UK but
every sea area mentioned in the shipping forecast ... not that it goes out
on any of the frequencies listed above.

(This transmitter a distinctly old tech device that relies on some special
valves that haven't been manufactured in decades: rumour has it that the
Beeb only have a handful left and, thanks to the power of the Murdochracy
over successive prime ministers--especially the current one--are far too
cash-strapped to consider replacing this transmitter with a device whose
continued maintenance would not require a time machine.)

--
Regards, Peter Boulding
(E-Mail Removed) (to e-mail, remove "UNSPAM")
Fractal Images and Music: http://www.pboulding.co.uk/
http://www.soundclick.com/bands/defa...&content=music

In article <jc9vs3$aes$(E-Mail Removed)>, Dave <(E-Mail Removed)> writes

>30 Hz-4 kHz, voice.
>4-25 kHz, unused guard band.
>25-138 kHz, 25 upstream bins (7-31).
>138-1104 kHz, 224 downstream bins (32-255).

Thanks.

>Bins above 1108Khz would seem out of band for plain vanilla adsl anyway ?

It's ADSL2+. Sorry, should have mentioned that.

--
(\__/)
(='.'=)
(")_(")

In article <jc9vs3$aes$(E-Mail Removed)>, (E-Mail Removed) says...
>
> "Mike Tomlinson" <(E-Mail Removed)> wrote in message
> news:PnwAd$(E-Mail Removed)...
> >
> >
> > a 17724 kbps sync with a 3.1dB SNR margin.
> >
> > There are these gaps in the tones:
> >
> > Gap1 1108kHz - 1113kHz (Tone 257)
> > Gap2 1479kHz - 1501kHz (Tone 343 - Tone 347)
> > Gap3 1548kHz - 1552kHz (Tone 359)
> >
> > Q: what is the cause of those gaps? Presumably interference of some
> > kind? Is there anything I can do about it?
> >
> > --
> > (\_/)
> > (='.'=)
> > (")_(")
>
> 30 Hz-4 kHz, voice.
> 4-25 kHz, unused guard band.
> 25-138 kHz, 25 upstream bins (7-31).
> 138-1104 kHz, 224 downstream bins (32-255).
>
> Bins above 1108Khz would seem out of band for plain vanilla adsl anyway ?
>
> Dave


With a sync of 17.724Mb It's ADSL2+, and this can have bins up to 2.2Mhz
AFAIR.

The interference might depends on where the OP is located, but there are
some high power broadcasters on these bands :

1107KHz Radio Belgrade (100Kw), RAI Rome (100Kw) and Voice of Palestine
(600Kw)
1494KHz Voice of Russia (600Kw) and Radio Jordan (1000Kw)
1548KHz Voice of Russia (1000Kw)

These might not cause a problem during the day, but at night these can
put HUGE signals into the UK.

In article <(E-Mail Removed)>, Gaius
<bin@127.0.0.1> writes

>The interference might depends on where the OP is located

Liverpool.

>These might not cause a problem during the day, but at night these can
>put HUGE signals into the UK.

This was actually about 0340 this morning, yes.

Would a few turns of the router phone line cord on a ferrite core help?
The phone line to the house is a fairly long (~50m) overhead drop, so
it's probably ideal for picking up unwanted stuff.

--
(\__/)
(='.'=)
(")_(")