Re: #audio #audio
“Things to try for more data points.
I’ll try these things.
Correct, on my old hardware, I loaded nwdr14 and then added my embellishments. No embellishments with the new hardware.
For the following, showudrc attached, I used only the RPi3, a single sd card with new nwdr14 image updated by piwiz and git pull on n7nix directory. The mic gain on the radio was set to 5. I swapped DRAWS hats. I still get a large difference in sensitivity to Audio In from the radio. For Audio Out, LO was -6 dB in all cases. I nulled the carrier for both hats at PT_P1, PT_P2, and PT_P3. I used
measure_deviate.sh –f 1042 –c left
Old DRAWS; PCM_-35.5 dB, New DRAWS; PCM_-13.5 dB
Old DRAWS; PCM_-30.5 dB, New DRAWS; PCM_-9 dB
Old DRAWS; PCM_-21 dB, New DRAWS; PCM_1 dB
I still worry about my DIY cable. I had problems making it correctly, got what I thought was correct and everything worked fine. Then, the new board came and the different audio levels blew my confidence. The Audio In level for the KPC3+ is closer to the old draws board. But I made that cable too.
From: email@example.com <firstname.lastname@example.org> on behalf of Basil Gunn <basil@...>
Sent: Thursday, December 12, 2019 10:32 AM
To: email@example.com <firstname.lastname@example.org>
Subject: Re: [draws and udrc] #audio
Trying to understand differences between the two units you are
Things to try for more data points.
1. swap RPi SD cards
2. swap DRAWS hat
One unit has a power-down switch?
What radio (make, model) are you using?
You set the lowest level (PTM_P1) for the DAC PowerTune control (DAC
Playback PT) which drops the LO Drive output voltage down to 330mv
P-P. What happens if you use PTM_P2?
See comment below.
David Lowry <huskyrunnr@...> writes:
> An RPi3 plus an older draws hat is running with nwdr14 and adc gain
> set to 0 dB. Audio knob from the radio is set to give an average level
> of 50 in received direwolf packets.
> An RPi4 plus the new draws hat with all else equal, I have to either
> crank the audio knob up a quarter turn or leave it and adjust adc gain
> to +7 dB in alsamixer to get the same average level 50 in direwolf.
> Both sets of hardware were updated through piwiz and git pull on the
> n7nix dir.
> direwolf is decoding equally well in either case so this may be a
> non-issue from a practical perspective. But should this be a concern?
> If not, I’ll happily move on.
> Thanks for any insight. I will not be able to respond with any
> requested console output until this evening. There are some snd_card_*
> differences between the boards from showudrc if that could be
> BTW, thank you Basil for your scripts. My students studied fm side
> band theory and ultimately used measure_deviate along with gnu radio
> and rtf-sdr to put it into practice. The project was well received.
Thanks and happy to hear that you found the script useful. Appreciate