Optimize the signal i received. – The Alexander association

This topic has 3 replies, 2 voices, and was last updated 2 weeks, 3 days ago by Eelco.

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27 December, 2024 at 11:20 #12700 Reply
Eelco
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Hi, i was able to decode the message transmitted by SAQ 24-12-2024 (saq twente) and i also used my own receiver (saq opname).
In the noise there is a signal but it is not good enough to decode with the gerke-decoder.
Is it possible to improve the recorded signal in a way the gerke-decoder could decode the transmission?
I have made the recording with audacity and the recording is named saq opname.aup3 and can be downloaded here.
https://edegraaff.stackstorage.com/s/bMNytHyRwB9rFEGC
I am curious if the recording could be improved and how.

Regards
Eelco de PD1EG
More about the SAQ project at my blog https://www.fishfreak.org/sdr/
- This topic was modified 2 weeks, 5 days ago by Eelco.
- This topic was modified 2 weeks, 5 days ago by Eelco. Reason: Improve text
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- 27 December, 2024 at 20:26 #12717 Reply
  
  rich.g.williams
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  PS I just had a look at your project file “saq opname.aup3” and unfortunately I can’t see any valid VLF there setting the waveform to spectral view. Looks like something has gone wrong and you are not recording VLF, should be frequencies up to about 21KHz. The spectral view should show several VLF stations with SAQ at 17.2KHZ but I don’t see any VLF stations in your file on the spectral view.
  
  Rich
- 27 December, 2024 at 20:09 #12715 Reply
  rich.g.williams
  Participant
  Hi Eelco.
  
  Suggest you can have a look at Listen to SAQ Its on this site its on “SAQ in the ether” then “Listen to SAQ” and scroll down to the title “Reception using an audio editor”
  
  It shows how you can setup Audacity’s filter curve to pass a very narrow band of frequencies around 17.2 KHz then it shows how to shift the pitch right down to 750 Hz. Then you can hear the morse code.
  
  Then save the audio file and try it with the gerke-decoder.
  
  Hope that helps,
  
  Rich
  - This reply was modified 2 weeks, 4 days ago by rich.g.williams.
  - 28 December, 2024 at 20:25 #12725 Reply
    Eelco
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    Hi, you’re right, I have done this with my previous recording, I will give it a try.
    
    This reply was modified 1 week, 5 days ago by AlexanderSAQ.
    
    This reply was modified 1 week, 5 days ago by AlexanderSAQ.
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