Mailinglist Archive: opensuse (4547 mails)

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Re: [SLE] Still cant connect to my ISP
  • From: "Carlos E. R." <robin1.listas@xxxxxxxxxx>
  • Date: Tue, 4 May 2004 00:44:45 +0200 (CEST)
  • Message-id: <Pine.LNX.4.53.0405040003200.11134@xxxxxxxxxxxxxxxx>

The Monday 2004-05-03 at 10:33 -0700, Jim Sabatke wrote:

> I believe that for US phones, 9600 is about at the baud limit. However,
> and not to be to pedantic, baud is not the correct term. Modems operate
> at a certain BPS (bits/sec.), which is not the same as baud. This is
> due to compression that allows a higher bitrate than baud rate.

Er... baud is not the same as bit rate, true, but it has nothing to do
with compression.

Baud (after J.M. Baudot) measures the signaling rate, ie, the rate at
which transmission-line changes are occurring.

For example, if we can play with 4 phase shifts of the signal, and two
amplitudes, we can transmit 8 values per change (0..7), ie, 3 bits, per
change. Thus, at a frequency of 2400 Hz, we have 2400 bauds but 19200 bits
per second.

(Don't take me too seriously, it has been years since I do these numbers).

The physical limits mentioned by the telephone companies come from several
things. Time ago, the limit was the bandwidth of the analog equipment
(specially for long distance using frequency multiplex). Now days, the
limit is that the signal is digitized at 1 byte x 8 KHz


And we are digressing a lot off topic, I suppose. O:-)

--
Cheers,
Carlos Robinson


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