Electrical Engineering - Re: AM radio: astronomically-high frequency modulator signal present on an astronomically-low frequ

Author

Re: AM radio: astronomically-high frequency modulator signal present on an astronomically-low frequ

jimp@specsol.spam.sux.com

2007-06-26, 5:25 pm

In sci.physics.electromag Randy Poe <poespam-trap@yahoo.com> wrote:
> On Jun 26, 1:35 pm, "John Campbell" <spaml...@spamless.com> wrote:
[color=darkred]
> I don't think I meant anything in particular about the DC component,
> but whether it's zero or there's a bias, I've always heard the
> statement "Ethernet is a baseband network" which means the
> carrier frequency is zero.

Does a digital signal, i.e. one where all the information is in
discreate voltage levels, really meet the definition of "modulation"?

I guess one could make the case that, using 5V logic for example, the
information varies a DC voltage of about 2.5V at the information
rate and thus "modulates" a 2.5V DC signal.

It certainly isn't AM as AM contains the multiplicative term sin(Fc)
which is zero for a DC carrier.

It isn't FM as the carrier frequency deviation is zero, thus the
modulation index is zero.

--
Jim Pennino

Remove .spam.sux to reply.

LinkBot