DSL line stealing when there is no tone - DANGER - Operational content

Alex Bligh alex at alex.org.uk
Wed May 16 21:03:30 UTC 2001


> I predict great profits for the first person to duct tape 100 'tracer
> tone-generators' into a 23 inch rack with 48v DC power source.

Not *quite* sure what you mean here, but you only need one
tone generator - all the rest can be done with passive
components. See (for instance) how tones were generated
in the days of mechanical exchanges (*not* one oscillator
per line)

I thought about this a bit later, and realised that on
ADSL (at least) it would be worth looking at the CPE.
This is busy generating a linecoding with
nothing in the sub 8kHz range. At the other end,
anything sub 8kHz is dropped. Getting the CPE
(via firmware, or internally) to stick some
tone on the line would be trivial. Of course
you'd need it as a configurable option in case
someone wanted to use it for voice too.

Alex Bligh
Personal Capacity

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