[amsat-bb] Re: First SSTV Rx

Greg D. ko6th_greg at hotmail.com
Fri Mar 27 22:09:34 PDT 2009

Hi Kent,

I think Gordon is on to something with the volume comment.  The image almost looks like it was recorded on a very bad mechanical tape recorder with a lot of wow/flutter - the lines aren't vertical, which means that the SSTV program is having a hard time synching onto the lines.  Since the recorder is digital, it can't be a mechanical problem, so the only thing left is the quality of the audio itself.

If there is a setting for the audio quality (vs record time, usually), pick a higher setting (lower record time).  You might also skip the audio cable and just put the recorder mike near the radio speaker, or turn the volume way down, sort of like you did when you played it back to the PC.

Ah, another idea...  Work on getting the radio->PC connection audio connection going (you can just use the national weather service channel for an audio source), and use the PC's audio recorder to get the sound quality and volume right.  I expect (though I haven't used MMSSTV or Windows for Ham stuff for several years) that you can play back the digital audio on the PC directly into MMSSTV.

Good luck,

Greg  KO6TH

> From: gordonjcp at gjcp.net
> To: amsat-bb at amsat.org
> Date: Fri, 27 Mar 2009 15:20:50 +0000
> Subject: [amsat-bb] Re: First SSTV Rx
> On Fri, 2009-03-27 at 07:24 -0500, Kent Frazier wrote:
> > Hi all,
> > 
> > After reading some of the posts about the SSTV on AO-51 I decided to give it
> > a try. I downloaded and installed MMSSTV and waited for a pass. There was a
> > good 40 degree pass over San Angelo, Texas beginning at about 00:14 UTC. I
> > connected my radio's data jack to my computer with my USB adapter and
> I usually just use the speaker connector.  The whole point of SSTV is
> that it is audio tones...
> > recorded the pass with my digital voice recorder. Lucky I did as nothing
> > showed up on the computer via the data jack connection. I used my Elk
> > Antenna to receive the signals.
> I try to record the signal rather than decode directly.  Make sure the
> recording isn't clipping, and that you are recording at a high quality
> setting.  If it sounds "okay" for voice, it won't be good enough for
> > After the pass I brought everything back into the house and connected the
> > voice recorder's ear jack to the computer's mic jack. After adjusting the
> > volume so MMSSTV wasn't complaining about an overload I ran the recording.
> > MMSSTV was in Auto Rx Mode and changed to Robot 36 as it received the
> > information.
> > 
> > The image isn't very clear, but at least I was able to receive something.
> > 
> > If anyone would care to look at the image and help me identify why it is not
> > clearer it would be appreciated. It has been uploaded to my photobucket
> > account at the following URL:
> > 
> > http://s226.photobucket.com/albums/dd316/badfrog88/Amateur%20Radio/?action=view&current=200903270131.jpg
> Kind of hard to tell.  Make sure the recording isn't clipped as
> mentioned before, and get a good music-quality recording rather than
> speech-quality.
> Gordon
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