On Tue, Jan 30, 2024 at 04:24 AM, Paul wrote:
Thanks for this Dave
AS expected replacing your Device with my II worked at treat.
Wonderful!
Signal to noise level output not great and is worse in the headset than it is on the sbitx speaker, however its not great there on mine anyway.
Some of that could be due to the resampling that I mentioned.? Ideally plughw should not be used.? One should know the sampling rate of each signal and set up each program to match.??
Also the arecord | aplay pipeline is reprocessing the signal.
From the arecord man page:
So it is using 8 bit samples at 8000 hz.??
Bottom line is I did not bother so far to see what sampling rate and sample size is being used in the sbitx_sound.c code when writing to the loopback device, but whatever it is, it would work better if they were all the same.
Also as I said already, 'sox' would be more efficient and would let you set gain and add filtering as it implements various 'effects'.
Turning the volume up on the sbitx just seems to make it worse.
My EE professor would smile now.? Amplifying a bad signal only makes it worse.? He was an analog guy.? In modern terms, resampling a sample just makes it worse.
The usable volume range is such that there is almost no audio until the volume control reaches a setting of 50+, a reasonably comfortable audio setting of about 86 is required to listen to the sbitx speaker.?
Might be partially due to arecord using 8 bit samples, not much dynamic range to work with.
Word of warning for anyone following this thread and using the 64-bit OS. if you boot the sbitx up with the USB headset plugged in, the sbitx app will not start,, unplug the headset and reboot again if this happens.
On the stock v3 sbitx I had a slightly different experience in that if I booted the radio up with USB headset connected, the headset would work in parallel with the sbitx speaker.
This is the physical names vs logical names issue I mentioned earlier.??
this command produces better output in my headset than I get from the sbitx speaker:
arecord -D "plughw:CARD=Loopback,DEV=1" -f cd | aplay -D "plughw:CARD=II,DEV=0"
Ok, you are proving what I said above.? This uses 'CD' format so not 8 bits at 8000 hz, instead 16 bits at 44,000 hz.
Just need to increase the volume to it now, perhaps using the rig volume control to allow the headset volume control the local control for fine adjustment
A step in the right direction me thinks
Agree.
?
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Regards,
Dave, N1AI
Dave, N1AI