Observation 3248: NOAA 19 (33591)

Regarding Observation 3248.

This is an early attempt to get NOAA APT on network.satnogs.org . Couple of points:

Thanks @BOCTOK-1 for scheduling! Keep them coming :slight_smile:

@pierros hm… not sure what could be wrong with the waterfall.

I guess we need to check the .dat file if it is not removed and also check logs for errors.

Nothing wrong with the waterfall. Just the flowgraph does not produce it :smiley:
We will fix it shortly.

The audio level is saturated and since the output from the FM demod is an AM modulated 2.4 kHz carrier, saturation in the audio level will reduce the dynamic range of the image. The APT decoder should complain about this.

The audio level should be around 50% - 70% of full scale. Note that APT uses 17 kHz deviation and bandwidth around 50 kHz.

It would be nice if we could upload decoded images (png or jpeg) using SIDS :slight_smile:

@surligas If I don’t make a mistake, this was generated with the fm_demod flowgraph. So, I think it should have a waterfall generated. Am I missing something?

@surligas ^ This something we should change on the flowgraph right?

It was decoded using the fm_demod or noaa_apt_decoder?

Demoded using fm_demod and then decoded with atpdecoder locally.

Sound level indeed seems to be an issue. Decoder is complaining for high volume.

Ok, I thought that you were using the NOAA flowgraph. I am pushing now an update to the NOAA decoder in order to produce also the .ogg file and the waterfall for compatibility with the fm_demod. From now on, I do not see any particular reason to use the fm_demod for NOAA APT transmissions.

@surligas Please also adjust the volume level (in case someone needs to do a decoding manually).

@cshields we can use your code now to select this flowgraph for APT modes :wink:

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Unfortunately for some reason journal, which logs client, had been stopped and it didn’t logged this observation. Also no .dat file, only a png file of 14KB size.

Not sure what went wrong, it seems that the other APT observation went well in terms of waterfall plotting.


check this branch https://github.com/surligas/gr-satnogs/tree/noaa_flowgraphs if everything is ok before I merge it to master.

It installs the satnogs_noaa_apt_decoder.py script that takes almost the same parameters with the fm_demod. For the additional parameters use the satnogs_noaa_apt_decoder.py --help

It requires a .png file name. If a NOAA image is decoded the flowgraph will automatically split the image in the two different channels, separating them with <file>_0.png and <file>_1.png.

Oops my bad… it is actually there the .dat file and by plotting it in my laptop looks fine. Not sure if it could overwrite the uploaded one to network. @comzeradd will reposting png image work, will it overwrite the current png image?

I got my answer, yes it does overwrite the png image. https://network.satnogs.org/observations/3248/ now with waterfall :slight_smile:

I’ve run gnuplot on rpi with the same .dat file and the png image was generated correctly. So, without logs I guess we are probably never be able to know what went wrong.

@surligas That’s nice, I’m going to check it today and I’ll prepare the code for satnogs-client in order to choose it when a noaa observation is scheduled.

Any update on this Fredy?

Unfortunately no… I was busy with ending docs for 0.3v and the hsgr station. I’ll update this thread as soon as I have something ready.