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Re: Topband: Light fiber question

To: Tom W8JI <w8ji@w8ji.com>, "Shoppa, Tim" <tshoppa@wmata.com>, Bruce <k1fz@myfairpoint.net>, "topband@contesting.com" <topband@contesting.com>
Subject: Re: Topband: Light fiber question
From: Bill Wichers <billw@waveform.net>
Date: Thu, 24 Oct 2013 17:39:00 +0000
List-post: <topband@contesting.com">mailto:topband@contesting.com>
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. 

I do agree with you that a simple run of decent coax is likely to be the better 
option though.

  -Bill

> Sorry, but by definition that is a modulator and demodulator.
> 
> You have to convert the radio signal to light, and that involves modulating
> a light beam of some type. At the other end, you have to demodulate the
> light into the original baseband.
> 
> You may not recognize it as a modulator/demodulator system, but that's
> what
> it is. You cannot just hook the coax to the fiber optic cable at each end.
> 
> 73 Tom

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