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@networkelements.com> To: <ietf@ietf.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@QUALCOMM.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@qualcomm.com> > > QUALCOMM Incorporated - Direct phone: (858)651-4478, Fax: > > (858)651-1102 > > > > >