= Сообщение: 7636 из 12491 ====================================== ENET.SYSOP = От : Markus Reschke 2:240/1661 28 Oct 18 16:12:28 Кому : All 28 Oct 18 16:12:28 Тема : baud or bps FGHI : area://ENET.SYSOP?msgid=2:240/1661+5b9e84cc = Кодировка сообщения определена как: LATIN1 ================================= Ответ: area://ENET.SYSOP?msgid=2:292/854+121b470f ============================================================================== Hi!
Baud is the unit of the symbol rate. 300 baud means 300 symbols per second. The unit for the data rate (or transfer rate or throughput) is bps (bits per second). These are two different things, but they are related by the number of bits one symbol represents.
Since we're talking about modems let us focus on POTS. The bandwidth of a voice call is about 3kHz. So any data modulation of a modem has to fit inside those 3kHz. So the industry agreed on a maximum symbol rate of 2400 baud. Up to 2400bps it's possible to transfer the data using a simple modulation, i.e. a symbol represents a single bit. Beyond 2400bps we have to use a more sophisticated modulation with one symbol representing several bits. For example, 9600bps is 4 * 2400bps. So each symbol represents four bits. The 9600bps can't be transfered via the 3kHz telephone line using the old and simple modulation with one bit per symbol. It wouldn't work because of the bandwidth limit. Same for 14400bps, still 2400 baud, but more bits per symbol. Later on with improved telephone networks the high speed protocols increased the symbol rate (baud) a little bit to get the maximum out of the 3kHz bandwidth.
What I've written above is a simplification. The reality is little bit more complex.
