[ILUG-Social] It's funny because it's true...

[Paul Jakma]

On Wed, 7 Nov 2001, Fergal Daly wrote:

> Broader than PSTN but not broad enough. There is actually a standard called
> BISDN where the B stands for Broadband, so even way back when it was thought
> up, they didn't consider ISDN to be broadband. As a student, I went to a
> couple of really tedious seminars about ISDN and BISDN (they were followed
> by booze!) and the guy was referring to ISDN as narrow band and that was
> 1995.
> 
> I don't think there's an official definition of broadband but a search on
> google for

hmmm...

well, in computing, broadband would seem to refer to analogue
electrical modulation of a digital signal.

the opposite being baseband, referring to digital electrical 
modulation. (ethernet).

interestingly, by this definition, you might consider a 33K6 modem 
connection to be broadband, however, luckily broadband is an old 
telco term and refers to bandwidths used of > 4KHz, so it's not.

(paraphrasing from Tanenbaum, and i'm sure the signals & EE codgers
on the list can/will correct the above as neccessary.).

So, is ISDN a baseband medium with the 3 channels mutliplexed onto it
via time division, or is it broadband using seperate bands for each
channel? if you heard it reffered to as narrow band, chances are it's
time division. (which fits in with how telco's aggregrate data
carries onto higher bitrate carriers.)

> glossary broadband
> 
> turns up a bunch of definitions that would exclude even dual channel ISDN,
> 
> Fergal

regards,
-- 
Paul Jakma	paul at clubi.ie	paul at jakma.org	Key ID: 64A2FF6A
Fortune:
A programming language is low level when its programs require attention
to the irrelevant.