🚀 go-pugleaf

Peter Chambers (peter@hightown.demon.co.uk) wrote:

> If your line was digital between a codec directly connected to modems
> at both ends this might be made to work. But it isn't. You have all
> of that analogue wiring as well.

Ask yourself what the bandwidth of the bit of copper going from my house to
the exchange is?  Very large isn't it?  (In fact I have two pieces of
identical copper leaving my house, one of which carries analogue phone
calls, and the other ISDN at 160 kbits/s.)  The copper wire doesn't go
though any multiplexers, it just goes straight to the codec at the exchange.

What may be a problem are the filters on the codec limiting the bandwidth,
but this isn't a function of a piece of copper :-)

> Ben Formesyn is right. You are limited by the Shannon Channel Capacity of
> real telecom lines. This seems to be little more than 33,000 bps according
> to results in the trade press.

If you substitute 'codec filters' for 'lines' in the above then you may well
be right.

-- 
|- Nick Craig-Wood ---------------------------------- ncw@axis.demon.co.uk -|
|---------- I've got this funny feeling I've seen this all before ----------|