l i n u x - u s e r s - g r o u p - o f - d a v i s
Next Meeting:
July 7: Social gathering
Next Installfest:
Latest News:
Jun. 14: June LUGOD meeting cancelled
Page last updated:
2001 Dec 30 16:58

The following is an archive of a post made to our 'vox-tech mailing list' by one of its subscribers.

Report this post as spam:

(Enter your email address)
Re: [vox-tech] help - dsl
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [vox-tech] help - dsl

On Thu, 26 Oct 2000, Mark Kim wrote:

> On Thu, 26 Oct 2000, Peter Jay Salzman wrote:
> > ok, now for the dumb question.   suppose you had a phone hooked up to a DSL
> > line, with no splitters or filters.  what would you hear?

DSL is a frequency-multiplexing scheme, with voice occupying up to 4kHz,
and data occupying various bands above 20kHz (to 1MHz?).  Some small
signal in the audible range might be noticable, depending on how good your
hearing is (supposedly good human ears can hear up to 22kHz).

> I think you aren't supposed to tell whether a telephone line has a DSL
> activated or not, so I guess you don't hear anything but a dialtone.  I
> think the idea is that you don't have to synchronize the installation of
> the filters with the DSL activation at the central office.

If you plug into the data line, the low-frequency dialtone shouldn't be
audible because is the design of the filter to block it out.

> Pacbell messed up our hookup, 

I thought you were going to do that yourself?

> so we have separated voice and data lines (three wires -- one shared
> between the two).

This should be easy to fix.  I cannot seem to find a schematic of a
splitter, but I would imagine it is something like the following (with
maybe some resistors as well):

       from CO
       |     |
       |     +---------+
       |               |
       +-------------- | ---------------+
       |               |                |
       |               |                |
 +-----+-----+         |           -----+-----
 | inductor  |         |            capacitor
 +-----+-----+         |           -----+-----
       |               |                |
       |      |C|      |  +----------+  |
       +------|a|------+--+ inductor +--+
       |      |p|      |  +----------+  |
       |               |                |
 +-----+-----+         |           -----+-----
 | inductor  |         |            capacitor
 +-----+-----+         |           -----+-----
       |               |                |
       +-----+   +-----+-------+  +-----+
             |   |             |  |
             voice             data

so it sounds like the final "common" (*) to the data connection didn't get
made, which should be straightforward to fix at the splitter.

> When I hook up a telephone
> to the data line, I don't hear anything (unless I have my DSL modem hooked
> up, in which case I hear negotation tones).

You do hear something?  High pitched? Interesting...

Jeff Newmiller                        The     .....       .....  Go Live...
DCN:<jdnewmil@dcn.davis.ca.us>        Basics: ##.#.       ##.#.  Live Go...
Work:<JeffN@endecon.com>              Live:   OO#.. Dead: OO#..  Playing
Research Engineer (Solar/Batteries            O.O#.       #.O#.  with
/Software/Embedded Controllers)               .OO#.       .OO#.  rocks...2k

LUGOD Group on LinkedIn
Sign up for LUGOD event announcements
Your email address:
LUGOD Group on Facebook
'Like' LUGOD on Facebook:

Hosting provided by:
Sunset Systems
Sunset Systems offers preconfigured Linux systems, remote system administration and custom software development.

LUGOD: Linux Users' Group of Davis
PO Box 2082, Davis, CA 95617
Contact Us

LUGOD is a 501(c)7 non-profit organization
based in Davis, California
and serving the Sacramento area.
"Linux" is a trademark of Linus Torvalds.

Sponsored in part by:
O'Reilly and Associates
For numerous book donations.