Re: [Sheflug] Modems

[nospam [at] alexhudson.com]

On Thu, Mar 22, 2001 at 02:23:08PM +0000, Will Newton wrote:
> > In defence of the Winmodem <pre-emptively ducking...> the one I put in my
> > kids PC seems absolutely fine..it can be faster than my external, consumes
> 
> Generally speaking, a modem is a modem is a modem. The bottleneck, by a
> distance, is the band-pass filter on your phone line. It's unlikley that
> one set of firmware will perform in a significantly different manner to
> another (that supports the same standards of course).

Actually, the band pass is usually there to filter out noise, and it's actually a low-pass (otherwise you wouldn't be able to use it to speak down :). There is a kind of band-pass - wire 3, bell shunt, but you don't put signal down that :) As for the rest of the line, well, generally the bandwidth going into people's homes is pretty high (or, at least, capable of being high), generally filtered below 500Hz (to loose mains, etc.) and 'filtered' (i.e., sampled) at 8kHz, leaving you with about 3.5kHz of bandwidth to play with if you're lucky.

Things most people aren't aware of: you need a digital exchange to get the high modem speeds (no, not everyone has these). Also, if you're stuck at 14, 28 or something like that it's more likely that your line has been multiplexed (I see this done more often in Uni, halls of residence, etc. - you can do signal analysis on the phone lines and prove it).

So I'd go for exchange and line equipment to make most difference - but I certainly agree it's unlikely to be the modem :-). 

Cheers,

Alex.

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