On Thu, Nov 23, 2000 at 01:08:17PM -0600, Mikkel L. Ellertson wrote:
> On Thu, 23 Nov 2000, mikeyw wrote:
>
> DSL "modems" are not realy modems. They are a router or bridge. But
> people are used to connecting to the Internet using modems, so the name
> carried over. Look up the definition of a modem sometime - they convert
> between digital and analog signals. A DSL connection is a Digital
> connection.
I believe a 'modem' is usually defined as a MOdulator/DEModulator. Then DSL
modems would indeed fit this descsription. And also that the
technology is not purely digital.
>From http://homepage.interaccess.com/~jkristof/xdsl-faq.txt:
[4.3]What is modulation?
Modulation is a prescribed method of encoding digital (or analog)
signals onto a waveform (the carrier signal). Once encoded, the
original signal may be recovered by an inverse process called
demodulation. Modulation is performed to adapt the signal to a
different frequency range than that of the original signal. Here's
how it flows:
bits -> modulator -> audio -> phone network -> audio -> demodulator ->
bits
Hence the name MODEM short for modulator/demodulator. The [DSL] modem
is necessary because the phone network transmits audio, not data bits.
The modem is for compatibility with existing equipment.
=========
Nice discussion of all of this in the referenced doc.
--
Hal B
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