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cjcliffe / CubicSDR

Cross-Platform Software-Defined Radio Application
http://www.cubicsdr.com
GNU General Public License v2.0
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What is the data format of I/Q audio output? #872

Closed tkzic closed 3 years ago

tkzic commented 3 years ago

Looking for documentation about the data format of I/Q output from CubicSDR. eg., CS8, CS16, etc.,

Thanks, Tom KA1IS

vsonnier commented 3 years ago

There is no IQ output in Cubic. If you mean the I/Q input, it requests CF32 to the SoapySDR driver level.

If you mean the Recording function, it is about audio WAV recording, one per-demod selected in the interface : it's format is PCM S16L Mono audio, except for FMS (FM Stereo) where it is Stereo.

dmaltsiniotis commented 3 years ago

According to the manual here https://cubicsdr.readthedocs.io/en/latest/application-window.html (and my own usage experience) I think @tkzic may be referring to the I/Q "de-modulator", which you can then record by pressing R to a wav file.

I/Q: Raw I/Q Pass-Thru (No Modulation) Raw I/Q samples that would normally go to a modem are passed through to the sound card for use elsewhere. Bandwidth is fixed to the selected sound card output frequency and will change along with it. Note that turning the Audio Gain down to a low level will disable gain completely and output the raw decimated samples.

I think @tkzic may be asking is: What is the IQ file format of this "I/Q de-modulator" output when recording it?

I actually have had the same question for some time, perhaps if it's a true pass-through it the same output as the SDR its receiving from?

Screen Shot 2021-01-29 at 13 23 51
vsonnier commented 3 years ago

Apparently, it generates 2 F32 audio samples per baseband-CF32, simulating Stereo: the Left channel being = Q (im) and the Right Channel = I (real) part. The resulting audio sample rate = the demod bandwith, unless I'm mistaken.

tkzic commented 3 years ago

Thanks vsonnier. That's exactly what I was looking for. Tom KA1IS