I see your point, since the signal is undergoing a conversion. My thinking
was modulator = baseband to some kind of RF or digital signal, i.e.
something very different from the original signal in terms of content of
the waveform. I wasn't thinking of using a band-limited section of spectrum
being converted to an amplitude-modulated light source as a "modulator" in
this case.
What I had meant was that the electrical->optical conversion doesn't have
to be a particularly fancy system when you're only trying to run about
200kHz of spectrum over the fiber in the 2(ish)MHz range. The basics I
mentioned before and some op amps are all that are needed. The op amps
will likely be the limiting factor for dynamic range.
It isn't the small bandwidth that matters, it is the dynamic range.
The most important part is people seem to think all noise comes from common
mode, and that suppressing common mode to non-harmful levels requires
extremes in isolation. That just isn't factual at all.
If someone has noise that is cured by going to a balanced line or extremes
in cable shielding or choking, they have something else wrong with their
system.
Some antennas and feed systems are just troublesome or nearly impossible to
design correctly, and some systems are designed incorrectly.
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Topband Reflector
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