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RE: FN-FORUM Modem oddity
date posted 8th January 2001 23:07
I gave up trying to work out the relationship between a modem's reported
speed and its actual speed quite a long time ago because modems seem to vary
so much. My old 28k modem always used to download at about 3.5 kbs per sec
and my current 56k seems to vary between 5.5 and 9kbs
Actually if a modem is for example rated at 28800 this is only an average
benchmark rating and depending on how clear from extranious noise and
interference a line is. It is feasible that a 28800 modem will exceed this
because modems send and receive data in packets which are checked out and
checked in, if a packet is damaged it has to be sent back and re-sent so
there is constant negations between modems because copper wire telephone
lines are not exactly the most reliable way to transfer data.
Saying that bearing in mind telephone companies these days often use fibre
optic cables and the lines have improved a great deal in recent years it may
in some instances be possible for a modem to run somewhat faster than its
rated speed and this may be particularly noticeable if you connect via a
Cable Telephone system because the lines are likely to be quieter so the
modem is working in an ideal world and if the modem was a quality piece of
kit in the first place its benchmarked speed rating should reflect its
performance under average conditions rather than ideal conditions. So it is
very likely going to exceed this under ideal conditions, by how much will
depend on how honest the manufacture was when they rated it in the first
place.
I sometimes wonder if my 56k modem is really a 9600 modem and I only think
it's 56k because I'm with NTL ;-)
Nick
http://www.artberry.net
-----Original Message-----
From: [EMAIL REMOVED]
[EMAIL REMOVED] Behalf Of Alison M Wheeler
Sent: 08 January 2001 16:41
To: [EMAIL REMOVED]
Subject: RE: FN-FORUM Modem oddity
Thanks David, and I would have to say that had I not seen and tested it I
would have said the same myself.
Further testing though has now shown it is related to the telco in use...
on BT line it gives the (expected) 28800 or less
on Cable London/Telewest it continues to give the high figure. I'm
wondering whether it is a protocol thing on Telewest's end using something
in the Hayes' encoding.
oh well. The person who busted the 'proper' card has said they'll buy a
replacement, so I should be able to give up worrying about it soon anyhow!
Rgds
Alison
-----Original Message-----
From: [EMAIL REMOVED]
[EMAIL REMOVED] Behalf Of David Nye
Sent: 08 January 2001 11:00
To: [EMAIL REMOVED]
Subject: RE: FN-FORUM Modem oddity
A 28800 bps modem cannot shift bits to another modem faster than 28800 - you
must be seeing the speed your o/s is using to talk to the modem card - which
is what Windows tends to show by default if the driver does not tell it
otherwise.
If it seems faster than the newer card, then this only suggests you were
never actually getting throughput of 44800 bps, but presumably something
less than 28800. Maybe the hardware compression works better on the old
card?
David Nye
http://dnye.com
Business Systems, Database & Internet Applications Design & Development.
Microsoft SQL Server, Access, ASP & VB Programming.
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