ADSL signalling - what happens on the physical layer?

Hi,
Does any one have any ideas on where I can find information on ADSL
signalling types?

Let me elaborate......

I'm keen on finding out what goes on at the physical layer. Is a carrier
ALWAYS present? Or does it require the equipment at the CPE to initiate a
connect to bring the signal from the exchange up? If the ADSL device at the
cpe DOES signal the exchange to start making a noise, then what sort of
initiation signal is sent?

With a scope or spectrum analyser, how would I measure the data rate? I know
the data rate is fixed by the ISP, as most routers will tell you the data
rate BEFORE authentication. How does the router perform this check?

In a nutshell, I'd like to be able to wake up an ADSL connection and get the
exchange to start the clock signal (I assume a clock is present) with
discreet components.

Now there's a challenge!

rig doc wrote:
> Hi,
> Does any one have any ideas on where I can find information on ADSL
> signalling types?
>
> Let me elaborate......
>
> I'm keen on finding out what goes on at the physical layer. Is a carrier
> ALWAYS present? Or does it require the equipment at the CPE to initiate a
> connect to bring the signal from the exchange up? If the ADSL device at the
> cpe DOES signal the exchange to start making a noise, then what sort of
> initiation signal is sent?
>
> With a scope or spectrum analyser, how would I measure the data rate? I know
> the data rate is fixed by the ISP, as most routers will tell you the data
> rate BEFORE authentication. How does the router perform this check?
>
> In a nutshell, I'd like to be able to wake up an ADSL connection and get the
> exchange to start the clock signal (I assume a clock is present) with
> discreet components.
>
> Now there's a challenge!


And this is cross-posted to uk.radio.amateur for what reason? Please
post to appropriate groups!

> And this is cross-posted to uk.radio.amateur for what reason? Please
> post to appropriate groups!
>

I use the uk.radio.amateur group regularly and there's a number of technical
souls there who may have the correct answer to my questions.... There's many
a radio ham heavily involved in data comms......

BTW, you also cross posted your gripe, so that makes you even more stupid
than me!!!

"know code" <(E-Mail Removed)> wrote in message
news:44033b4b$0$39293$(E-Mail Removed)...
>
>
> And this is cross-posted to uk.radio.amateur for what reason? Please post
> to appropriate groups!
>

You can post any clap trap you like to this forum...I refer you to the
Wiltshire Womble.

HTH
tox

On Mon, 27 Feb 2006 17:39:48 -0000, "rig doc" <.> wrote:

>Hi,
>Does any one have any ideas on where I can find information on ADSL
>signalling types?
>
>Let me elaborate......
>
>I'm keen on finding out what goes on at the physical layer. Is a carrier
>ALWAYS present? Or does it require the equipment at the CPE to initiate a
>connect to bring the signal from the exchange up? If the ADSL device at the
>cpe DOES signal the exchange to start making a noise, then what sort of
>initiation signal is sent?
>
>With a scope or spectrum analyser, how would I measure the data rate? I know
>the data rate is fixed by the ISP, as most routers will tell you the data
>rate BEFORE authentication. How does the router perform this check?
>
>In a nutshell, I'd like to be able to wake up an ADSL connection and get the
>exchange to start the clock signal (I assume a clock is present) with
>discreet components.
>
>Now there's a challenge!
>

It isn't as simple as just a clock, or a single carrier. ADSL in
UK is a multichannel system known as DMT. The spec is fully given by
G.992.1 and other standards it may refer to (I don't have a copy here
to check) including the method of training the connection.

The data-rate is the result of a combination of all the channels.

The whole thing is far too complex for a newsgroup posting, but
searching on the ITU spec given, and reading that spec should get you
a long way.

I am, for the moment, ignoring ADSL2+ as it isn't widespread yet.

Regards,
Harry.

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"rig doc" <.> wrote in message news:(E-Mail Removed)...
> Hi,
> Does any one have any ideas on where I can find information on ADSL
> signalling types?
>
Google and a bit further on in the book you're quoting from. It just takes
a bit of effort to find the info yourself, or if you have a real question
just ask it.

rig doc wrote:
> Hi,
> Does any one have any ideas on where I can find information on ADSL
> signalling types?
>
> Let me elaborate......
>
> I'm keen on finding out what goes on at the physical layer. Is a carrier
> ALWAYS present? Or does it require the equipment at the CPE to initiate a
> connect to bring the signal from the exchange up? If the ADSL device at the
> cpe DOES signal the exchange to start making a noise, then what sort of
> initiation signal is sent?
>
> With a scope or spectrum analyser, how would I measure the data rate? I know
> the data rate is fixed by the ISP, as most routers will tell you the data
> rate BEFORE authentication. How does the router perform this check?
>
> In a nutshell, I'd like to be able to wake up an ADSL connection and get the
> exchange to start the clock signal (I assume a clock is present) with
> discreet components.
>
> Now there's a challenge!
>
>

You can get G.dmt (G992.1) normally 96 Swiss Francs from www.itu.int -
they give three free downloads. The ANSI Txxxx standard is >300 dollars.

Andy.