Re: #audio #audio


 

"I use the 9600 bps connection even with 1200 baud data which just selects the
Kenwood discriminator output (PR9 Output 9600 (bps)) ie. pin 4 on the
mDin6 connector is selected by ALSA setting IN1."

Thank you, this works well with my old board. For the setalsa-tmv71a script, is the switch file placed in /etc/ax25 manually or does some other script do that? 

I am still having issues though. With the new board, alsa parameters from setalsa-tmv71a run with the discriminator, I barely get any modulation at all, judging from the spectrum of measure_deviate.sh -f 1042 -c left .

I looked for a spot on the board to measure V p-p and I noticed that the 100 Ohm resistors from the low pass audio filters, the ones where C17 and C20 are removed, are labeled differently between boards. On my old board, they are marked 101, which I am guessing is 10*10^1 Ohms. On my new board, they are marked 104, which I am guessing is 10*10^4 Ohms.

Audio In is still a bit low on this new board as well.

Could you folks confirm whether or not  the "104" resistor could account for my output sound level discrepancies between my boards? Should I try to jump those "104" resistors?

I've attached a photo of the area where C17 and C20 are removed. The two "104" resistors are the ones in between where those C's were.

David


From: udrc@nw-digital-radio.groups.io <udrc@nw-digital-radio.groups.io> on behalf of Basil Gunn <basil@...>
Sent: Friday, December 13, 2019 10:30 AM
To: udrc@nw-digital-radio.groups.io <udrc@nw-digital-radio.groups.io>
Subject: Re: [draws and udrc] #audio
 

> What deviation should I shoot for on the tm-v71a?

From page 83 of the Kenwood TM-V71a manual
Select 1200 or 9600 bps for the data transfer rate, depending on your TNC.
1200 bps: Transmit data input (PKD) sensitivity is 40 mV p-p , input impedance is 10 kΩ.
9600 bps: Transmit data input (PKD) sensitivity is 2 V p-p , input impedance is 10 kΩ.

I use the 9600 bps connection even with 1200 baud data which just selects the
Kenwood discriminator output (PR9 Output 9600 (bps)) ie. pin 4 on the
mDin6 connector is selected by ALSA setting IN1.

Then you can control your packet data speed with a single setting in
/etc/direwolf.conf MODEM 1200 or MODEM 9600.  Make sure your Kenwood
Menu 518 is set to DATSPD 9600.

/Basil n7nix

David Lowry <huskyrunnr@...> writes:

> Well, I must have done something to the first board during my cable fiasco a year ago.
>
> I’ve had a tm-v71a since the first of last summer, new-in-box until this morning. I set it up. This eliminates my mad cable skills and gives me some known ALSA parameters from setalsa-tmv71a.sh. PCM for the old hat needs to be set much lower. PCM for the new hat is much closer to the script values, not sure what deviation the script is shooting for. Audio In looks right for the new board as well.
>
> Bryan, is it possible to fubar that ti chip in a way that increases sensitivity? Because that is what it appears I have done. In any case, both hats work reliably on both xmit and rev.
>
> What deviation should I shoot for on the tm-v71a?
>
>



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