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Re: AO-40 FEC



Phil how about a win doze version
nick
----- Original Message ----- 
From: "Phil Karn" <karn@ka9q.net>
To: "David Giles" <vk5dg@corprit.net>
Cc: "AMSAT-BB" <amsat-bb@AMSAT.Org>
Sent: Friday, July 18, 2003 12:28 PM
Subject: Re: [amsat-bb] AO-40 FEC


> David Giles wrote:
> > Hello all,
> > 
> > Just tried Phil's ao-40 FEC telemetry software - I'm impressed.
> > Copied good blocks down to MA of 249 and a squint of 120 degrees.
> > It didn't even raise much of a sweat - the reed-solomon code
> > wasn't used, the viterbi decoder did the job.  
> > I'll have to try it with a smaller antenna next time.
> 
> James G3RUH is reporting good FEC results from apogee with just a 
> 1/4-wave GROUND PLANE receive antenna. So your 4-foot dish is enormous 
> overkill. Harder to point, too. :-)
> 
> I'm beginning to think about a modified form of my FEC format that would 
> be useful for communications through the transponder. Because I'm not 
> constrained by the existing spacecraft beacon hardware, I have the 
> option of using a different modulation format. I'm thinking of BPSK with 
> a residual carrier, a NRZ channel format (i.e., no differential 
> Manchester coding) and possibly a higher symbol and/or data rate. This 
> should make text chatting through the satellite possible with very small 
> antennas.
> 
> Phil
> 
> ----
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