Re: sysadmin qualifications (Re: apt-get vs. aptitude)
On Mon, 14 Oct 2013 23:37:25 -0400
Jerry Stuckle <jstuckle@attglobal.net> wrote:
> No, a cable modem does both MOdulation and DEModulation - which is
> why it is called a MODEM.
>
> On the internet, input/output on one side of the modem is digital,
> through an RJ-45 to category cable.
>
> But you can only have one digital signal on a wire. On the other
> side of the modem is 75 ohm coax cable. You *could* run the digital
> signal on this cable for a few hundred feet (some systems claim up to
> around 1500 feet), but this signal would not be compatible with the
> other signals (standard and hi-def TV and possibly music channels).
> As a side note, multiple hi-def TV signals, even though they are all
> digital, would not be able to share the same cable as digital
> signals, either.
>
> Therefore, all these signals (including your internet) are modulated
> onto analog RF signals. Each signal has its own band, or range of RF
> frequencies it uses (a signal is not a single frequency). And coming
> the other way, the signal from the cable must be demodulated to
> convert it back to digital.
>
> The cable company has another cable modem on the other end of the
> line to convert the signals between analog and digital, also.
>
> So, you can see, a cable modem truly is a modem.
Right you are. I stand corrected.
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