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Re: SSTV on transponder sats



Of the last half dozen messages sent regarding SSTV and voice, one item
continues to be ignored.  SSTV is nothing more than a CW signal varied in
frequency and therefore has a one hundred percent duty cyle.  Voice SSB
has something like a one third to one half duty cycle which means the
transponder is working that much less on SSB voice!  Cliff K7RR


On Mon, 2 Oct 2000, Jon Ogden wrote:

> on 10/2/00 2:29 AM, Howard Long at howard@howardlong.com wrote:
> 
> 
> > 
> > Although I've not tried it myself, I have heard SSTV on the transponder
> > sats. Generally I'm not aware of this being thought of as bad practice,
> > although I may be wrong.
> > 
> > So my question is: What's the difference between running SSTV and FM voice
> > when it comes to bandwidth and power budget?
> > 
> > Let me make it clear, I'm certainly not promoting FM voice on transponder
> > sats at all!
> 
> Well, let's look at it this way:
> 
> 1.) SSTV can be run either over FM or over SSB
> 2.) Running it over SSB will take less bandwidth than FM
> 3.) SSTV is a very high duty cycle just like RTTY.  This is where the
> dilemma comes in.
> 4.) The linear birds (FO20 and FO29 and AO10) are so minimally used that it
> really doesn't hurt or rob power if it's you and a few other folks.
> 
> The best advice is to just use common sense.
> 
> Now on P3D, there will be separate digital bands and perhaps this is where
> SSTV could go (I think of SSTV as a DATA mode and feel it should be moved
> from the USA SSB phone sub-bands to the CW/data sub-bands.).
> 
> 73,
> 
> Jon
> NA9D 
> 
> -------------------------------------
> Jon Ogden
> NA9D (ex: KE9NA)
> 
> Member:  ARRL, AMSAT, DXCC, NRA
> 
> http://www.qsl.net/ke9na
> 
> "A life lived in fear is a life half lived."
> 
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