Waiting for demoded data

SatNOGS Software
1

Hello,

While browsing transmissions I see that a lot of them say “Waiting for demoded data” in the ‘Data’ panel. What does that mean? Is it a failure during decoding?

Thanks!
Lorenzo

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2

It means that network waiting data from the client that performed the observation. If the observation is more than 1h in past you can say 99.99% safely that it is not going to get any data. Usually if there are any data they are uploaded during the pass or in the next couple of minutes after the pass.

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3

Thanks!
Is it possible for the network to extract the data from the raw observation audio or is that something only the client does?

4

You can get the audio file of an observation and run it through a decoder, however have in mind that audio is compressed and limited in bandwidth. In some cases you may decode something in some other not.

Are you interested in a specific satellite or you experiment?

5

I was mostly experimenting, in particular I was looking at SSTV transmissions from the ISS. For example this observation:
https://network.satnogs.org/observations/1307022/
Which is waiting for the demoed data. I downloaded the audio file as you suggested and it actually decodes pretty well and you can see two images!
It would probably be nice to do decoding on the server side as well, useful for instance if you are gonna add new decoders in the future.

6

@ar3itrary is working on an SSTV decoder and it goes pretty well. Until this work merge with the gr-satnogs I’m running a script for decoding SSTV images and upload them. It works like you do, downloading the audio, run it through a decoder (qsstv) and uploads the result but in a automate way.

Not sure why it skipped that observation, it should have decoded it and uploaded the results, I could have a look when I go back home (after new year’s eve).

The main problem is that the source data you have are compressed, otherwise it can work.

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7

Hey @fredy, will the script decode SSTV images observed by your station or on all stations? I also decode it myself via downloaded audio. Thank you!

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It works for all stations, but checks only the observations that are vetted as good.

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