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Re[2]: IRC Server



guy keren <choo@actcom.co.il> wrote:

>      furthermore - a 14,400 bps modem still works at 2400 BAUD. even the 
>      28,800 modems work at 2400 BAUD. the theoreticall limit for modems 
>      that are allowed to make a delay of up to 2 bits in transmission is 
>      a bit below 32,000 bps (not INCLUDING data compression done on top of 
>      that), so faster modems requiere one of two:
>        1. allow for a higher delay.

>From 'The Free On-line Dictionary of Computing':

********************************************************************************
* ... each baud may carry
* between 1 and 16 bits depending on the coding (eg. QAM). Where data is
* transmitted as packets, eg. characters, the actual "data rate" of a channel is 
* 
*         R * D / P
*
*
* 
* where R is the "raw" rate in bits per second (including packet overhead), D is
* the
* number of data bits in a packet and P is the total number of bits in a packet. 
********************************************************************************

Thus, maximum RAW i/o you can get with 2400 baud is 2400*16=38,400 bps - not
much better that mentioned 32,000.

>        2. (what is usually done) use a line with a larger bandwidth 
>           (phone lines give you a range of 3.6Khz for data transmission - 
>           remove this limit, and you can get to MUCH MUCH higher rates on 
>           these SAME phisical lines). as far as i know, this is an 
>           international standard, and not just a bezeq standard - the 3.6KHz 
>           thingy. i might also be wrong, since i only assume so).

Could you please explain, how with 3.6kHz bandwith lines folks get something
better than 3600 bps (probably, times some factor near 1, depending on bandwith
definition)?!

Evgeny



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