doc:appunti:linux:audio:audio_recording
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doc:appunti:linux:audio:audio_recording [2019/04/22 22:57] – [Wireless UHF microphone on Android] niccolo | doc:appunti:linux:audio:audio_recording [2020/12/27 08:34] – [Electrical compatibility and hardware autodetection] niccolo | ||
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{{wireless-mic-receiver.jpg? | {{wireless-mic-receiver.jpg? | ||
- | To connect the receiver to the Ugreen | + | To connect the **UHF receiver** to the **Ugreen |
- | ^ Male Jack 3.5 mm TRS ^ Signal | + | ^ 1/4" TS female jack ^ Signal |
- | | **Tip** | + | | **Tip** |
- | | **Ring** | + | | | Not connected |
- | | **Sleeve** | + | | **Sleeve** |
- | ===== Wireless | + | The **2.6 volt** current provided by the USB adapter on th **jack ring** will go nowhere (not connected). The **2.6 volt** current provided on the **jack tip** is probably not required by the UHF receiver, but **it should not harm**. **No infromation** is available about **microphone impedence** expected by the USB adapter, on the other hand no information is available about the **impedence of the mic interface** of the UHF receiver. |
+ | |||
+ | Despite all this empirical approach, the **voice registration is quite satisfying**! | ||
+ | ====== Audio Recording With Android ====== | ||
+ | |||
+ | Recording audio using an **external microphone** connected to an **Android device** can be a real nightmare. We tried the hard way using a Chinese, no-brand, **wireless | ||
+ | |||
+ | We can group the problems you can face in three main categories: | ||
+ | |||
+ | * Physical connection | ||
+ | * Electrical compatibility and hardware autodetection | ||
+ | * Software capabilities and settings | ||
+ | |||
+ | ===== Physical connection ===== | ||
+ | |||
+ | Most Android | ||
+ | |||
+ | So, connecting an external microphone, can be as simple as making a cable that connects the **ring** and the **sleve** of the **CTIA connector** to (respectively) the **ground** and the **microphone line** of the microphone. The hard part is to guess, or empirically try, if the microphone **requires a bias current**, if the Android device is provinding such a current and if the microphone produces a sufficient **output level** (actually a voltage in the order of the millivolts) that can be used by the device. | ||
+ | |||
+ | ===== Electrical compatibility and hardware autodetection ===== | ||
+ | |||
+ | 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**. | ||
+ | |||
+ | 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**, | ||
+ | |||
+ | ===== Software capabilities and settings | ||
+ | |||
+ | FIXME Complete the article! | ||
Wishing to connect the **UHF microphone** to an **Android smartphone**, | Wishing to connect the **UHF microphone** to an **Android smartphone**, | ||
- | ^ Male Jack 3.5 mm TRRS (CTIA) | + | ^ 1/4" TS female jack ^ Signal |
- | | **Tip** | + | | | Not connected |
- | | **Ring** | + | | | Not connected |
- | | **Ring** | Ground | + | | **Sleeve** |
- | | **Sleeve** | Microphone | + | | **Tip** | Microphone |
The smartphone **did not sensed the microphone**, | The smartphone **did not sensed the microphone**, | ||
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* [[https:// | * [[https:// | ||
* [[https:// | * [[https:// | ||
+ | * [[https:// | ||
+ | * [[https:// | ||
+ | * [[https:// | ||
+ | * [[https:// |
doc/appunti/linux/audio/audio_recording.txt · Last modified: 2020/12/28 18:22 by niccolo