At 04:46 PM 5/16/01, Greg Maxwell wrote:
On Wed, 16 May 2001, Steve Schaefer wrote:
The main reason not to stick a tone on the DSL line is that the line coding (2B1Q) used by SDSL uses the baseband (low frequency part of the spectrum).
For line codings that don't use the baseband (CAP, DMT and variants like G.lite), the DSLAM (telco central office DSL equipment) is always set up so that the DSL can be combined with a voice circuit over the same pair, so it still doesn't put a tone on the line.
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.
Better: a chip with a recorded voice: "This pair is in use" interspersed with a tone. While present baseband signalling may be unable to handle such, it'd be useful if future ones purposely avoided the zero to 5kHz spectrum to allow for such a mechanism. Clearly the telco workers have demonstrated the absolute necessity for such a facility. ----------------------------------------------------------------- Daniel Senie dts@senie.com Amaranth Networks Inc. http://www.amaranth.com