Since you're using 1200bps, are you sure you're using the correct pins and setting on your FTM400 (DON'T use the discriminator interface):

? 1. Use the correct I/O pins on the FTM400:
??? --
??? pin 1 - PKD (packet data input) (300 mVp-p)
??? pin 2 - GND
??? pin 3 - PSK (PTT)
??? pin 4 - RX 9600 (9600 bps packet data output)?? <----------- do NOT use this pin
??? pin 5 - RX 1200 (1200 bps packet data output) (300 mVp-p)
??? --

? 2. Make sure you have the radio set to "1200BAUD" mode aka.? pre-emphasis / de-emphasis enabled

?

? PDF page 161
? --
? Item #12 : Radio Menu --> Data --> Data Speed --> Data : 1200bps
? --

--David
KI6ZHD

On 08/11/2021 06:36 PM, Craig, KM6LYW wrote:

copy that, thanks, so no alsa-soft-preamp then??? There's many .asoundrc examples, with people getting 120% volume, but none
of them seem to work in my implementation.

I'm using the 1200baud output of the yaesu-ftm-400 into the line-in of the audio-injector.? Direwolf only sees a volume of 20 to 30.? We want an aver age of 50.

I didn't consider the mic input, as I just assumed the impedance missmatch would have "dire" equalization consequences.

I'll look for dc offset too - thanks!



-craig
KM6LYW

On 8/11/21 5:43 PM, David Ranch wrote:

I assume you're looking to do 9600bps or faster FSK packet.? If not, you should not use the "9600 baud" or discriminator port as your signals need the pre-emphassis/de-emphassis for standard 1200bps AFSK packet.? Anyway, assuming 9600bps is the goal, you're right.. the output signal levels from the FTM400 aren't adjustable which is really unfortunate.? Instead of using the line-in on the "Audio Injector Z" sound device, does it have a microphone input as well?? If so, give that a try as microphone ports usually have more gain available to them.

Ps.? check to see if there is a DC BIAS voltage on the that Audio InjectorZ microphone port using a volt meter.? If it does, you need to make sure that the FTM400 either has a coupling capacitor on it's audio output line OR you should just add a 10uF ceramic capacitor between the devices to block that DC voltage to avoid possibly damaging your radio.

--David
KI6ZHD

On 08/11/2021 04:24 PM, Craig, KM6LYW wrote:

I started using an "Audio Injector Z" audio hat with a Pi which has a -6dB hardware cut on the Line-In.

The line/discriminator output of my Yaesu ftm400 is not adjustable, so levels are low on direwolf (20-30, while we want 50 on average).

Has anyone come up with a working alsa software preamp or other way to increase gain on Line-In beyond what alsamixer allows?

I've tried and failed to get all of the various .asoundrc incantations to work.? I'm looking for a software solution.? If more hardware
is required (preamp/opamp), I'll probably just chuck the hat in the bin.


curiously,
-craig
KM6LYW