Create Network Transceiver - DVPi Audio In/Out adjustment

I will make a video for this post and post it on YouTube. (Next monday)

Describes the settings for DVPi audio input/output. If you are familiar with Linux, you probably already know. In particular, if you are transmitting too loud or too small when you are TX Mode, be sure to read this article.

This is very important for using DVPi well, Let me explain how I set it up.

1.Connection of sound-related devices

DVPi uses a USB sound card. Below is the USB sound card I use. 

You may use an external speaker. If you have a spare computer speaker, you can use it as is. Just connect the external speakers to the sound card's headphone connector.

However, I decided to connect the small amplifier and the speaker directly to embed it in the case.

Audio Out and In are connected as shown below. GND is common, so only one is connected.

I have used an amplifier like the LM386 so far. I was looking for an easy way to make it and found the product below. As a 5Volt amplifier for less than $1, I was quite satisfied.

I bought PAM8403, but you can use what you can easily buy around you.

It is equipped with a variable resistor, making it easier to use.

I decided to use only one channel. That's enough.

2.DVPi Audio In/Out Tuning (It is important)

 To use DVPi well, please set it up once.

 If your Raspberry pi or sound card is replaced, you will need to set it up again.

 

 2.1 Execute putty.exe

  putty.exe can be downloaded from the Internet.

You can find the IP assigned to DVPi  by dhcp in DVPi's Config window. 

Enter the IP address of your DVPi and click the Open button.

Perhaps the first time you connect to your DVPi with Putty, you will get the following warning. Ignore and click Yes.

 2.2 Login SSH (putty.exe)

  Login as (ID): pi

 Password    : dvpi

If login is successful, the screen below appears.

 2.3 Execute alsamixer and Select 'USB Sound Card'

Type alsamixer and Press the 'Enter' Key

The screen below will appear.

Press F6 on your keyboard.

The sound card selection window appears as shown below.

Press the arrow keys (Down) on the keyboard to select'USB Audio Device'.

 2.4 Adjust 'Speaker' and 'Capture' 

Then, the screen to set the volume of'USB Sound Card' appears as shown below.

When the speaker is selected, press the up or down arrow keys on the keyboard to change the speaker volume.

I recommend setting the speaker volume to 90% or higher.  You can adjust the actual volume through the variable resistance of the amplifier.

Press'F5' to adjust the volume of the microphone connected to the DVPi.

Press'F5' on the keyboard.

The'Capture' item is also displayed as shown below.

Press the right button of the arrow keys on the keyboard to move to CAPTURE.

Press the up and down arrow keys to select the volume that is right for you.

(Caution: You do not need to adjust the MIC displayed in the middle)

When all adjustments are done, press the'ESC' button to exit.

On the Internet, it is recommended to run the 'sudo alsactl store' command after adjusting the volume.

Enter'sudo alsactl store' and press enter Key.

3.conclusion

I set the audio out to 100% (Speaker : 100) and then adjust the volume using the variable resistor connected to the amplifier. This works pretty good.

I first set the MIC (Capture) volume to medium, and then I attached a variable resistance to the MIC.  The volume of the microphone was also adjusted through a variable resistor, but noise was generated in my case.

It is recommended that the microphone be adjusted as described above, preferably without variable resistance.

thank you for reading.

KD8CEC, Ian