In dial-up what is the sceintific reason for the noise produced when establishing a connection?

Answer 1

When two modems are communicating over a phone line, they use audio signals at specific frequencies as the "0" and "1" of binary code. That noise you hear is the rapid alternation of audio signals between those two frequencies. They do this since phone lines were designed to transmit audio frequencies, so the modems use audio frequencies to communicate in binary form.
It's that simple.

Answer 2

It's called 'handshaking'. When computers talk using a dial-up conection they do it via a modem, which essentially converts the digital signal into sounds that can be carried using the normal telephone call technology. The sounds change in pitch very fast as the digital 'messages' being sent change, and involve the modulation of a 'carrier' tone which is audible. Before the two machines can talk together they need to agree a 'protocol', i.e. decide how fast the machines at either end can send and receive data, agree on a common speed they both share etc. Fax machines do the same thing, and you can hear the noise here as well. It's a more complex version of the sounds send down the line when you actually dial a number using 'tone dialling'. Because both machines have to understand these messages no matter how fast or slow they can run, the signals are very slowly changing and so quite distinctive to hear. When handshaking is agreed, then there is the business of 'logging on', the home machine tells the remote one who the user is, what his password is etc. and the remote machine agrees to allow him access or not. All this takes place before you actually have a working connection. Once you have a connection, the machine then knows for sure that what is taking place is not a voice call, so the speakers are then muted so that the sound doesn't any longer get heard. It is still going on though, and if you can 'listen in (e.g. by picking up another phone extension) you will still hear it.

Answer 3

Our computer technology is base on binary mathematical concept; which convert everything to either "0" or "1".

Everything word, image and concept can be converted in binary, that's how the computer reads information and store it in the harddrive and memory.

for example, numerical number would be translated into:

our read out Computer reads
1 00000001
2 00000010
3 00000011
4 00000100
5 00000101 and etc. (you get the idea)

Now, when these data are communicated over the modem, the sound you heard when the modem are connecting is the acutally sound of the binary number being converted into high pitch and low pitch.

A high pitch would translated into "1" and low pitch would be "0", the speed of the modem dictates how fast these binary gets through to the other side. If you happen to pick up the phone while using modem, you would actually hear the noise of high/low pitch being transmitted over the telephone.

Now if you say something at the phone while the computer is transmitting, you would actually interrupt the connection; because your voice is being translated to the other computer and it can not make sense of what that data is.

Answer 4

Sounds good what well travelled said - but ever noticed its the same as a fax line too!
must be some kinda cyber talk!

Answer 5

Don't know.... but i'll be watching here for Reply

Answer 6

NO

Answer 7

i dunno but i remember it was annoying lol