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doc:appunti:linux:audio:audio_recording [2019/04/23 12:49]
niccolo [Web References]
doc:appunti:linux:audio:audio_recording [2019/05/22 15:51] (current)
niccolo [Electrical compatibility and hardware autodetection]
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 As stated above, the first problem is **powering the microphone** itself, because generally we will use an **electret** one. It is a **common practice** to provide the power on the same line of the microphone signal, so **requiring just two wires** for both power (from the device to the mic) and for signal (from the mic to the device). The power, also called //bias current//, is generally in the range of **2.5** to **5.0 volt**. As stated above, the first problem is **powering the microphone** itself, because generally we will use an **electret** one. It is a **common practice** to provide the power on the same line of the microphone signal, so **requiring just two wires** for both power (from the device to the mic) and for signal (from the mic to the device). The power, also called //bias current//, is generally in the range of **2.5** to **5.0 volt**.
  
-FIXME: How much current ​is provided in our test? Is the current always present or switched-on only at jack insertion?+On a Xiaomi Mi A1 smartphone, which has a **TRRS 3.5 mm jack, CTIA standard**, we measured a bias current ​of **2.19 volt** between ​the microphone (sleeve) and the ground (ring).
  
 Another parameter which should be considered is the **impedence** FIXME Another parameter which should be considered is the **impedence** FIXME
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   * [[https://​forum.xda-developers.com/​showthread.php?​t=1042051|App that turns off microphone AGC (Auto-Gain Control)?]]   * [[https://​forum.xda-developers.com/​showthread.php?​t=1042051|App that turns off microphone AGC (Auto-Gain Control)?]]
   * [[https://​stackoverflow.com/​questions/​47394634/​difference-between-voice-communication-and-mic-in-mediarecorder-audiosource|Difference between VOICE_COMMUNICATION and MIC in MediaRecorder.AudioSource]]   * [[https://​stackoverflow.com/​questions/​47394634/​difference-between-voice-communication-and-mic-in-mediarecorder-audiosource|Difference between VOICE_COMMUNICATION and MIC in MediaRecorder.AudioSource]]
 +  * [[https://​stackoverflow.com/​questions/​47359587/​what-is-the-best-audiosource-setting-for-calls|What is the best audiosource setting for calls?]]
 +  * [[https://​amp.reddit.com/​r/​androidapps/​comments/​4wo8sz/​app_to_force_android_to_use_external_microphone/​|App to force android to use external microphone when one is plugged in]]
doc/appunti/linux/audio/audio_recording.1556016572.txt.gz ยท Last modified: 2019/04/23 12:49 by niccolo