Re: modems

So the modems change binaries such as the protocols developed by IETF to
analog, I didn't know that. I remember acc/couplers. I had an exaternal 300
bps modem once, wow things have changed. My speaker goes off after
handshaking.
----- Original Message -----
From: "Nepple, Bruce" <bnepple(_at_)networkelements(_dot_)com>
To: <ietf(_at_)ietf(_dot_)org>
Sent: Tuesday, June 11, 2002 8:17 PM
Subject: RE: modems


> Are you sure the sound he is hearing is not the modem fan screeching?  :P
>
> > -----Original Message-----
> > From: Pete Resnick [mailto:presnick(_at_)QUALCOMM(_dot_)COM]
> > Sent: Tuesday, June 11, 2002 1:37 PM
> > To: Lloyd Wood
> > Cc: Bill Cunningham; ietf
> > Subject: Re: modems
> >
> >
> > On 6/11/02 at 9:04 PM +0100, Lloyd Wood wrote:
> >
> > > You're confusing your modems and your acoustic couplers.
> > >
> > > An electrical transmission in the ~3.5kHz bandpass range that equates
> > > to the dominant frequencies used by the human voice, which the phone
> > > system was engineered to convert and carry easily, is not a sound.
> > > Modulating an electrical signal into said electrical
> > transmission does
> > > not involve sound.
> > OK, OK, of course that's exactly correct; almost all modems today
> > completely bypass the issue of sound and transmit directly through
> > the copper to the telephone switch. But let's get back to the
> > question Bill was asking and why he was asking it:
> >
> > >  On 6/11/02 at 3:22 AM -0400, Bill Cunningham wrote:
> > >
> > >  >I know modems communicate on the physical layer by
> > electrical pulses
> > >  >or binaries sent on copper wires.
> > The important feature of modems is that they send analog signals over
> > those lines, not digital (which is what I took Bill to mean by
> > "binaries"). And those analog signals correspond quite directly to
> > things that create sound (if connected to a speaker of the right
> > sort) and receive sound (if taken from a microphone of the right
> > sort). It is the correspondence to the receiving and production of
> > sound that makes modems interesting devices; that's why acoustic
> > couplers worked on the old modems. Similarly touch tones are *tones*
> > because they can pass through a system designed for transmitting
> > analog electrical signals that can be turned into a sound. (Hence,
> > you could go out and by those touch-tone producing boxes, program
> > phone numbers into them, hold them up to your phone receiver, and get
> > the number dialed.)
> >
> > Yes, it is correct that most modems today deal with electrical
> > transmission only and not sounds (except for their speakers). But it
> > is the fact that those signals can easily become sounds that is key,
> > at least to explain to Bill why his modem is screeching. (Although
> > some of my friends in philosophy of science disagree, "explanation"
> > is not a matter of reducing everything to physics.)
> >
> > It's times like this I think the IETF needs more academics. :-)
> > --
> > Pete Resnick <mailto:presnick(_at_)qualcomm(_dot_)com>
> > QUALCOMM Incorporated - Direct phone: (858)651-4478, Fax:
> > (858)651-1102