[MLB-WIRELESS] Connecting nodes/clusters and expanding the mesh via Internet tunnels.

[John Dalton]

> What can we do over a POTS link?

Two 33k modems back to back are pretty well state of the
art over a 'standard' (as in telephone to telephone) circuit
with a bandwidth of around 3kHz and 'standard' equipment
at each end.

The copper from your phone to the exchange is not the factor
that limits the data rate (as shown by 56k modems and DSL/ADSL).
For a 'standard' voice circuit the exchange acts as a bandpass filter,
limiting the maximum data rate to around 33k.  Typically ISPs will
have a digital connection to the exchange, eliminating a
digital-analog-digital conversion stage, allowing the data rate to
be pushed as high as 56k.  For a price, Telstra will effectively
widen the bandpass filter in the exchange.  This service is otherwise
known as DSL or ADSL.

It may be possible to get more than 33k, over a standard line, by using a modem
which uses Turbo coding (http://www331.jpl.nasa.gov/public/JPLtcodes.html)
to do its data transmission.  As far as I know, no one manufactures ACA approved
turbo coded modems.  I guess it *might* be possible to use a modem in voice mode,
and run a turbo coded modem as a user application, simply using the modem hardware
as an analog/digital converter.  Turbo decoding is very computationally intensive,
so the average PC may not have sufficient power to support a data rate greater than
33k.

Regards
John

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