Re: #audio #audio


 

OK, I attached the wrong file. Sorry. Here is the showudrc for the powertune/single-Pi/single-sd card experiment.


From: udrc@nw-digital-radio.groups.io <udrc@nw-digital-radio.groups.io> on behalf of David Lowry <huskyrunnr@...>
Sent: Thursday, December 12, 2019 6:22 PM
To: udrc@nw-digital-radio.groups.io <udrc@nw-digital-radio.groups.io>
Subject: Re: [draws and udrc] #audio
 

Thanks Basil,

 

“Things to try for more data points.
1. swap RPi SD cards
2. swap DRAWS hat”

I’ll try these things.

“One unit has a power-down switch?
dtoverlay=gpio-shutdown,gpio_pin=6,gpio_pull=up”

Correct, on my old hardware, I loaded nwdr14 and then added my embellishments. No embellishments with the new hardware.

“What radio (make, model) are you using?”

Yaesu FT-2980.

“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?”

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

PT_P3:

Old DRAWS; PCM_-35.5 dB, New DRAWS; PCM_-13.5 dB

PT_P2:

Old DRAWS; PCM_-30.5 dB, New DRAWS; PCM_-9 dB

PT_P1

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.

David



From: udrc@nw-digital-radio.groups.io <udrc@nw-digital-radio.groups.io> on behalf of Basil Gunn <basil@...>
Sent: Thursday, December 12, 2019 10:32 AM
To: udrc@nw-digital-radio.groups.io <udrc@nw-digital-radio.groups.io>
Subject: Re: [draws and udrc] #audio
 

David,

Trying to understand differences between the two units you are
using.

Things to try for more data points.
1. swap RPi SD cards
2. swap DRAWS hat

One unit has a power-down switch?
dtoverlay=gpio-shutdown,gpio_pin=6,gpio_pull=up

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
> relevant.
>
> 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
the feedback.
/Basil n7nix



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