HFU HF Underground
General Category => General Radio Discussion => Topic started by: Hornet0123 on December 17, 2014, 2051 UTC
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I recently started trying to decode wefax, I have bee mostly getting junk. I have tried decoding from coast guard in Boston New Orleans, and Cali. I have tried using Virtual Audio Cable, also tried running a cable from my speaker out jack back into the mic jack. I have tried on my desktop (pentium quad core, 16 gigs) and my laptop (I5 8gigs). I keep getting distorted pics. Any Ideas?
(https://fbcdn-sphotos-d-a.akamaihd.net/hphotos-ak-xpf1/v/t1.0-9/10478151_10205300638218111_6083831267419542651_n.jpg?oh=faeb7f9fdc3f877e3265127146c1331b&oe=553E1120&__gda__=1430781791_3816f84cc3e1d432234aef3bef2911b8)
(https://scontent-b-lga.xx.fbcdn.net/hphotos-xap1/t31.0-8/10842044_10205300636738074_7521393102008170133_o.jpg)
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It looks like the signal is properly tuned and noise free. Is the software trying to detect the sync pulse at the end of each line, or free running? If the former, try the latter. Also, double check that the lines per minute is correctly set, to 120 ,if that is an option.
Shameless plug time, if you have an iPhone/iPad or an Android, give my app a try :-)
http://www.blackcatsystems.com/ipad-iphone-ipod-touch-shortwave-ham-amateur-radio-app/HF-Weather-Fax-radiofacsimile-nws-noaa-maritime-marine-high-seas-forecast-sailing.html
http://www.blackcatsystems.com/droid/hf-weather-fax.html
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I'm not sure about your first question, I will poke around a bit to try and find out, Lines per minute are set to 120. I do have an ipad, will try that tonight
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Whenever I try using one of the virtual soundcards, I get distorted fax reception also. I believe the virtual soundcard occasionally drops small bits of audio (undetectable to my ears, but not to the decoding software). The same thing happens when I try to receive sstv using the virtual soundcard.
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You mentioned you tried using a patch cable from the speaker out to mic jack - so I assume you're using some SDR software? Could it be dropping samples? I use SdrDx and have no issues with that. I also use Soundflower as the virtual audio cable, but that's a Mac OS X only app.
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I am still playing around with settings. I have noticed setting BOTH recording and playback of the virtual soundcard to 16 bit 48000 Hz gives the best results (but still not perfect) on my system (Windows 8.1). I did not have these issues with my old XP machine.
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Well it seems to be an audio issue in my computers. I tried decoding a youtube wefax , got the same thing- nice clear lines, but distorted. I installed your app on my ipad, same thing. However I just did a decode from new orleans CG on my tecsun portable with the ipad app.... it was a bit fuzzy, but everything lined up perfect. I am using an SDR (afedri with SDR Console V2.3)
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Hmmmmm. I am also using an afedri with sdr console (versions 1.5, 2.2, and 2.3).
I don't know if I have tried receiving FAX or SSTV with SDRdx, I will try that when I get a chance.
Hoping it is not an afedri issue.
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Ok, well I seem to gave solved it, it was a couple pieces of software causing the problem. I was messing around on my lunch decoding a recording, I scrapped the virtual audio cable software and tried one called ab-cable. It started working. When I got home a tried it with my SDR, but I was still getting distortion, although not as bad. I downloaded a different program, HDSDR, and bingo. Clear copy
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Okay! I couldn't find the ab-cable software you mentioned, but I did find vb-cable and installed it.
Also, made sure everything was set to the same bit rate,etc....
Now copying FAX with no timing gliches -- YAY!
Still using SDR Console. If SDRdx had an easier way to manipulate the spectrum width and center frequency (similar to SDR Console), I would use it more (SDRdx has better audio quality than SDR Console, and marginally better AGC).
(http://i1296.photobucket.com/albums/ag16/refmo/FAX/test2_zps64cf44e1.png)