There is an I2S bus running at 192ksps.? That drives the audio DAC (and also the ADC).? I'm referring to V11 software, V12 could be different, but probably not.
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Now in the audio data stream (Process.cpp) the audio is interpolated up to 192ksps before driving the output.? So you could tap in at some point before the interpolation
and it might work better.? Experiments could be easily tried.
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Anyhow, the Open Audio library can re-sample to 44.1ksps, and then you can drive a USB output object.? In theory anyway, I haven't tried that.? You should get clean audio.
I went through this same process recently, it looked to be more trouble that it was worth because 48ksps is not in the audio library, and I bailed out to a lazy man's (practical) hardware solution.
I think we need to nicely ask Paul to get other sample rates added to the audio library.
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It is also interesting that the original convolution receiver project could change sample rates.? T41EEE is now running the transmitter at 48ksps, and also the receiver at 48ksps (receiver during calibration only).
A future version of T41EEE will have more flexible sample rates for both transmitter and receiver.? This will simplify the zoom and hopefully get power consumption reduced (low power battery mode).
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73 Greg KF5N
