I asked this in the element chat but figured it should belong here in case anyone else encounters this issue.
I am trying to use the satnogs dockerized version and I am struggling to determine how to get the client to export the iq recording at the sampling rate specified for the sdr
For reference I am using kng’s dockerized version.
So far I have explored changing the the find sample rate python script to return always the sample rate of the sdr rather than the calculated sample rate based upon the satellite but that doesn’t seem to change it all (I think it is something to do with satnogs_fm but not sure what parameter needs to be changed).
I would appreciate any suggestions since I am working with s-band reception and being able to schedule passes while at work would be helpful.
Hi there,
The flowgraphs always decimate down to a observation bandwidth, which is calculated in each flowgraph. The code in find_samp_rate.py is a copy of this as the results isn’t available outside the flowgraphs, it is not the SATNOGS_RX_SAMP_RATE.
Using IQ dump in this container is documented here.
Basically, you need to bind mount to the host, tell -client to create it there, then rename it after observation ends to it is unique and does not get overwritten.
Additional info, the different flowgraphs have their own way of calculating the sample rate, fm always runs at 48k for instance, as does a few others, shown here. If you want to run a higher rate (wider spectrum) you need to schedule a mode that results in this, for example fsk or bpsk, and a appropriate baudrate with that.
If you know a satellite that has a transmitter that isn’t in the DB, please do suggest it and it can be added.
Okay. So if I am understanding this correctly, the sample rate is tied the flowgraph and cannot be changed.
At this point I have the normal iq_dump script working correctly and have the iq recordings accessible outside the container but was hoping to get iq files with the raw SATNOGS_RX_SAMP_RATE as the sample rate.
Ok, in that case you need to modify the flowgraphs to do that.
In satnogs-flowgraphs you need to edit all 13 flowgraphs, move the iq sink block to connect to the soapy source directly. you will loose the doppler correction as that is done with the decimation.
If you’re already using my addons, you can simly put all the .grc in the addons/grc/ dir and build the addons, this should result in overwriting the packages ones.
Running this on a rpi might not work, depending on your storage solution.
It’s better to describe what you want to accomplish, else I’m just describing some of the possibilities blindly.