Demodulate LRPT from Satnogs IQ file

SatNOGS Software
62

Hmm. I’ve just realised the soft symbol files (and by default IQ files) are in /tmp not /tmp/.satnogs and therefore being stored on the SD card:

pi@pinog:~ $ df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/root        29G  4.6G   23G  17% /
devtmpfs        841M     0  841M   0% /dev
tmpfs           970M     0  970M   0% /dev/shm
tmpfs           970M   22M  949M   3% /run
tmpfs           5.0M  4.0K  5.0M   1% /run/lock
tmpfs           970M     0  970M   0% /sys/fs/cgroup
tmpfs           970M  934M   36M  97% /tmp/.satnogs
/dev/mmcblk0p1  253M   52M  202M  21% /boot
tmpfs           194M     0  194M   0% /run/user/1000

I guess it would make more sense to store them under /tmp/.satnogs to write less to the SD card?

63

Hello everybody

I moved all the demodulation process to the raspberry pi and worked!
Thanks @mat for the bug fix in the flowgraph, I forgot to change the Float to Char block on the first try and of course it failed.

But now is working fine.

meteor_20200623
meteor_202006231568×936 491 KB

Next step is to use process_meteor.py to call medet on the pi and upload the results to the network :grinning:

1 Like
64

This Meteor-2 observation 2431133 has a strange waterfall. As the IQ file is available here, I wonder if processing with the new scripts get something out of it. And also, what could have happened during the observation ?

65

Thats probably the LRPT transmitter on the sat resetting…

Since the default flowgraph for LRPT is going to be the FM demod flowgraph, the receive bandwidth of the IQ file is only 48 kHz, which is too small to be able to decode the LRPT signal (~72 khz).

66

Hi guys

Finally, I have everything working in the raspberry. I had some trouble to upload the files to the database, and also some issues with file permissions.

Here is the pass of this morning.
Observation 2452146

Does anybody know why there is no color in the image? Seems like a problem in the satellite, maybe some channels are not working properly. The infrared image is always black also.

Maybe we can create a wiki or tutorial with the updated setup for Meteor decoding. What do you think?

67

My most recent METEOR observation is in colour so unless it’s changed mode by location then I don’t think it’s that. Have a look at what settings you’re passing into medet, th

I don’t think the satellite is transmitting the IR channels. I’ve disabled that part of the script on my station.

2 Likes
68

Thanks! that was the problem I had -r 65 -g 65 -b 65 instead of -r 65 -g 65 -b 64 it’s a big difference for such a small change.

I need to understand how these channels work and how to combine them.

Will try to re upload the correct result