non-binary computers?

From: Eric Smith <>
Date: Fri Sep 3 19:45:40 1999

> So, for example the binary number 1001101 (7 bits) could be
> sent, in trigital, as 2212 (4 bits), theoretically saving bandwidth.
> (Whether it actually *would* or not, I'll leave to the theorists)

Except that it isn't base 3, this is how modern modems work.

Your standard V.34 modem can transfer data at up to 33.6 Kbps. But it
actually uses under 4000 baud. That's because a baud is NOT defined as a bit
per second. Rather, it is defined as a signal change per second, and the
modem uses a large number of symbols (collectively called a constellation)
instead of just binary.

The tradeoff is that it can use a narrower frequency band than might
otherwise be necessary, but it need a better SNR (signal-to-noise ratio).
For the telephone system, which has a hard limit of under 4000 Hz
(typically 3300 Hz), this tradeoff is obviously worthwhile. But for
other transmission media such as coaxial cable or radio, it's usually
better to use fewer symbols and more bauds.
Received on Fri Sep 03 1999 - 19:45:40 BST

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