[amsat-bb] Fox-1A decoded after adjustments to 'Filter Length'

Chris Thompson g0kla at arrl.net
Fri Oct 9 16:29:38 UTC 2015


It seems unlikely that a small movement in the filter length would make
such a dramatic difference.  It's possible it reduced the load on your CPU,
but that also seems unlikely.  A slow computer usually misses audio first
because it can not keep up with the sound card.  That is why we track
missed audio at the bottom of the window.

So this could have been a coincidence?  But maybe not.  We left the filter
controls on the program for just this sort of experimentation.  So keep at



On Fri, Oct 9, 2015 at 6:28 AM, Bob KD7YZ <kd7yz at denstarfarm.us> wrote:

> I'd left this run all night as well as SatPC32 to move the antennas.Now
> using FCDP+.
> Yet only one decode listed this morning.
> So on the 1205Z pass I listened to the audio. If I moved the focus of
> the freq indicator, with the mouse, I could see "nearly" an Eye as I'd
> seen when running the test-wav yesterday.
> So I adjusted the slider for "Filter Length (sample)" in the upper-right
> of the program window.
> Voilla!, I began seeing decodes mount up. Throughout the remainder of
> the pas (circa 40% of what it could have been) I tested moving the
> "Filter Length" back to 512. This only caused the "EYE" to distort and
> decodes to stop. I tried 256 and 320 but always returned to 448 as seen
> in the screenshots IF they can make it to the AMSAT-BB.
> Now I need an expert to explain why that worked.
> --
> 73,
> Bob KD7YZ
> www.qrz.com/db/kd7yz
> AmSat LM#901

Chris E. Thompson
chrisethompson at gmail.com
g0kla at arrl.net

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