[A-DX] Unslanting the images by changing the playback speed of your recording (defekter CD-Spieler.......)

[Roger]

Am 24.11.2013 19:59, schrieb VOA Radiogram:
> One more note about this weekend's slanted images...
> In Fldigi, the RX correction of -2250 ppm (parts per million) worked 
> for most of us.
> -2250 divided by 1,000,000 is -.00225, or -0.225%
> If you have recorded the program, and if you have the recording 
> software Audacity, you can select Effect > Change Speed > and enter 
> the Percent Change -0.225. From the resulting audio, you should get 
> unslanted decodes of the MFSK images. You can do this for the entire 
> program, or just for the images. (Remember to set the Fldigi RX ppm 
> correction back to zero, or to wherever it is normally.)
> You might have to adjust the -0.225% for best results on your PC.
> If you have another recording software application that can change 
> speeds, make a similar adjustment.
> The problem may have been that the CD player used to feed VOA 
> Radiogram audio into the transmitter was slightly off speed.
> This did not affect the decoding of the text modes because they are 
> much more tolerant than MFSK images of slight changes in speed.
> To review, you can unslant the images by adjusting the playback speed 
> of your recording, as described above, or from your direct reception 
> using Fldigi: Configure > Sound Card > Settings > Corrections > RX ppm 
> set to -2250
> Roger in Germany documented his successful decoding of the images here:
> www.rhci-online.de/VoA_Radiogram_2013-11-23.htm
> <http://www.rhci-online.de/VoA_Radiogram_2013-11-23.htm>One more 
> broadcast today at 1930-2000 UTC on 15670 kHz.
> This weekend, which started as a disaster for VOA Radiogram, has 
> turned out to be very instructive.
> Kim
> voaradiogram.net

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Ohne die digitalen Bilder hätte es Keiner gemerkt, das der CD-Player für 
die Sendung eine Geschwindigkeitsabweichung von -0.225% hatte.
Gab es nicht früher bei Vinyl-Geräten Muster für den Plattenteller, um 
die Geschwindigkeit zu kontrollieren... ..  ?

http://tinyurl.com/ljlmamy



roger