Extra bandwidth without voice?

Was thinking in the shower today (dangerous, I know)

ADSL is predicated on data signals being added to a voice line, with the
DSL frequencies being filtered so that a human doesn't hear them on the
phone.

Since the vast majority of people don't use their landlines and rely on
their mobiles, what's stopping providers from offering data-only lines,
dropping the portion of the spectrum used for voice calls and using that
for data as well? That would result in an increase in bandwidth, but
how much, I don't know.

Thoughts?

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

In article <(E-Mail Removed)>, (E-Mail Removed) (Mike Tomlinson)
wrote:

> what's stopping providers from offering data-only lines,
> dropping the portion of the spectrum used for voice calls and using
> that for data as well?

That's called ISDN.

--
Paul Cummins - Always a NetHead
Wasting Bandwidth since 1981

In article <(E-Mail Removed)>, Mike Tomlinson wrote:
> ADSL is predicated on data signals being added to a voice line, with the
> DSL frequencies being filtered so that a human doesn't hear them on the
> phone.
>
> Since the vast majority of people don't use their landlines and rely on
> their mobiles, what's stopping providers from offering data-only lines,
> dropping the portion of the spectrum used for voice calls and using that
> for data as well? That would result in an increase in bandwidth, but
> how much, I don't know.

ADSL frequencies go up to about 1MHz, while telephone audio is about 3kHz,
so it would give an increase in available bandwidth of about 0.3%.

That's assuming the bandwidth available for ADSL goes all the way down to
3kHz of course, which in practice it probably doesn't, so the available
increase might be a little more than 0.3%, but it still seems hardly worth
the bother.

Rod.
--
Virtual Access V6.3 free usenet/email software from
http://sourceforge.net/projects/virtual-access/

"Mike Tomlinson" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>
> Was thinking in the shower today (dangerous, I know)
>
> ADSL is predicated on data signals being added to a voice line, with the
> DSL frequencies being filtered so that a human doesn't hear them on the
> phone.
>
> Since the vast majority of people don't use their landlines and rely on
> their mobiles, what's stopping providers from offering data-only lines,
> dropping the portion of the spectrum used for voice calls and using that
> for data as well? That would result in an increase in bandwidth, but
> how much, I don't know.
>
> Thoughts?

The spectrum for telephone audio is from (nearly) zero to about 4khz. The
spectrum used by ADSL starts at about 8kHz and extends to about 1.1MHz. So
by using the zero to 8KHz band the you would gain a further 0.8% bandwidth.
You would of course have to have different equipment (or equipment capable
of switching between the two options).

ISDN uses the spectrum zero to 80 kHz. ADSL Annex B (as used in Germany)
coexists with ISDN and to achieve this the ADSL spectrum uses 138kHz to
1.1MHz. I suspect this has been done because ISDN is a widely-used business
system in Germany. It may also be that from the outset the German PO had
more satellite exchanges in rural areas so that the "last mile" of copper is
really that, and not the "last 8 miles" as is common in UK rural areas.
However, sacrificing nearly 15% of the ADSL bandwidth for ISDN does not look
nearly such a good idea, when you consider that VoIP would probably be a
better choice for the future.

I seriously doubt that "vast majority of people don't use their landlines".
I suspect that the proportion of people for whom this is true is actually so
small that it does not warrant the setup of different equipment.

The solution is to replace all the copper pairs with fibre, and deliver
ethernet to each consumer. Then for a voice service, the user simply plugs
in a VoIP phone. Mobile phones could work the same way - simply arrange for
the mobile system to allocate an IP address to each handset, and you have
VoIP throughout.

--
Graham J

Mike Tomlinson submitted this idea :
> Was thinking in the shower today (dangerous, I know)
>
> ADSL is predicated on data signals being added to a voice line, with the
> DSL frequencies being filtered so that a human doesn't hear them on the
> phone.

Surely, that's the other way round. The human, analogue devices, are
filtered to prevent them interfering with the DSL signal.

>
> Since the vast majority of people don't use their landlines and rely on
> their mobiles, what's stopping providers from offering data-only lines,

Technically, nothing prevents this.

They already do what you suggest - check out SDSL.

> dropping the portion of the spectrum used for voice calls and using that
> for data as well?

> That would result in an increase in bandwidth, but
> how much, I don't know.

Not a lot.

>
> Thoughts?

On 03/07/2011 08:37, Mike Tomlinson wrote:
>
> Was thinking in the shower today (dangerous, I know)
>
> ADSL is predicated on data signals being added to a voice line, with the
> DSL frequencies being filtered so that a human doesn't hear them on the
> phone.
>
> Since the vast majority of people don't use their landlines and rely on
> their mobiles,

A rather sweeping statement?
I for one prefer to use my landline for voice calls, for two reasons;
speech quality and not wanting to be interrupted with work problems when
I'm off-duty. My work-provided mobile gets switched off after work and
stays that way until I'm on duty again.
It's called work-life balance... ;-)
I've not yet found any compelling reason for having a mobile of my own -
I just borrow my wife's if I really need one.
Then of course, there's TXTing, which to me is a complete waste of time...

George Luddite

On Sun, 03 Jul 2011 10:59:08 +0100
George Weston <(E-Mail Removed)> wrote:

> On 03/07/2011 08:37, Mike Tomlinson wrote:
> >
> > Was thinking in the shower today (dangerous, I know)
> >
> > ADSL is predicated on data signals being added to a voice line,
> > with the DSL frequencies being filtered so that a human doesn't
> > hear them on the phone.
> >
> > Since the vast majority of people don't use their landlines and
> > rely on their mobiles,
>
> A rather sweeping statement?
> I for one prefer to use my landline for voice calls, for two reasons;
> speech quality and not wanting to be interrupted with work problems
> when I'm off-duty. My work-provided mobile gets switched off after
> work and stays that way until I'm on duty again.
> It's called work-life balance... ;-)
> I've not yet found any compelling reason for having a mobile of my
> own - I just borrow my wife's if I really need one.
> Then of course, there's TXTing, which to me is a complete waste of
> time...
>
> George Luddite

Agreed, on most counts.

Since the wife doesn't have a mobile, ("over my dead body"), I got the
cheapest possible for use in the car in case of need. I don't work now,
so no chance of having an employer's one any more.
Texting, don't get me started. It's main purpose, apart from unlearning
how to spell English, seems to be proving that your other half
is involved with another 'amour'.
See: Kwame Kilpatrick, ex-mayor of Detroit, who exchanged 14,000 (yes,
14,000) explicit text messages with his female Chief Of Stuff, sorry,
Staff. He is no longer Mayor of Detroit. They used City-owned 'phones,
the fools, all messages were produced in court. Oops.
--
Davey (semi-Luddite).

En el artículo <(E-Mail Removed)>, Jono
<(E-Mail Removed)> escribió:

>Surely, that's the other way round. The human, analogue devices, are
>filtered to prevent them interfering with the DSL signal.

That's what I said... "with the DSL frequencies being filtered so that
a human doesn't hear them on the phone."

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

En el artículo <4e103a09$0$2482$(E-Mail Removed)>, Graham J
<graham@invalid.?> escribió:

>I seriously doubt that "vast majority of people don't use their landlines".
>I suspect that the proportion of people for whom this is true is actually so
>small that it does not warrant the setup of different equipment.

It's be interesting to see definitive figures. I hardly ever use mine,
and I know very few of my friends do. Most mobile tariffs include a
generous allowance of calls (perhaps it works better for men than women
).

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

In article <(E-Mail Removed)>,
Jono <(E-Mail Removed)> wrote:

>Surely, that's the other way round. The human, analogue devices, are
>filtered to prevent them interfering with the DSL signal.

That shouldn't be necessary, as the DSL signal processing should
effectively filter it out anyway. Older phones on the other hand
weren't designed to be robust against the frequencies used by DSL.

In practice it appears that phones do interfere with DSL equipment,
but whether this is due to the audio frequencies themselves I
don't know.

-- Richard