Modern wireless headphones have become an integral part of the digital lifestyle, and the Xiaomi Air 2 (also known as the Mijia Air 2) is a prominent representative of this segment, many users perceive them as a “black box”: taken out of the case – they earned, removed – they turned off. However, behind this simplicity lies a complex chain of technological processes that ensure stable communication and quality sound.
In this article, we will take a closer look at the physics and logic of the device so you understand what is going on inside when music is paired or played, and understanding these processes will help you not only use the gadget more efficiently, but also correctly diagnose possible problems in the future.
We're going to look at the radios, the circuit synchronization algorithms, and the energy-saving features that make it easy to operate, and it's not just a manual to turn on, but a deep analysis of how engineering is done in a compact package.
Technology of wireless sound transmission Bluetooth 5.0
The foundation of Xiaomi Air 2 is the Bluetooth 5.0 protocol. Unlike previous versions, this standard provides significantly higher data transfer speeds and increased signal range, which helps achieve a stable connection even when there are obstacles between the smartphone and headphones.
A key feature is the use of dual signaling technology. TWS-One channel received the signal from the phone and transmitted it to the second (Slave), which led to desynchronization and increased battery consumption. Xiaomi Air 2 implemented a scheme where both headphones receive data independently or with minimal relay delay.
It is important to note that all functions require support for appropriate profiles on the part of the smartphone. The device automatically determines the available codecs and selects the best option for transmitting the audio stream.
⚠️ Warning: If you are in an area with a lot of Wi-Fi routers or microwave ovens, there may be short-term interference, which is because Bluetooth and Wi-Fi are in the same 2.4 GHz frequency band.
The stability of the connection also depends on the antenna built into the case, Xiaomi engineers placed it so that the user’s body minimally shields the signal when the smartphone is in his pocket.
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For maximum range of connection, try not to cover the case of the smartphone with your palm if it lies in the back pocket of the trousers, as the human body contains a lot of water and absorbs radio waves.
The principle of operation of sensors and automatic pairing
One of the most convenient features of the model is the automatic on and pairing when extracted from the case, which is controlled by optical and capacitive sensors located on the inside of the bowls. When you remove the earphone, the sensor detects the change in lighting and the break in contact with the charging pads.
At this point, the microcontroller commands the activation of the Bluetooth module, and if the device has been paired with a smartphone before, it instantly starts searching for the last connected gadget, the entire process takes less than two seconds, creating an “instant start” effect.
Touch control is implemented through capacitive panels that respond to touch with your finger, and the system distinguishes between single, double and long presses, putting the device in the appropriate modes of operation:
- 🎵 Single touch — Play/Pause or answering the call.
- 📞 Double-touch – activation of voice assistant or re-setting.
- 🔇 Retention (3 seconds) – switching between noise reduction modes (if supported by the Pro version) or turning off the microphone.
It's important to understand that sensors require direct contact with the skin, and working with thick gloves can make it impossible to control, because the capacity of the finger will not be transmitted to the sensor.
To reset sensor settings or forced soldering of the connection, there is a special algorithm activated by prolonged retention of sensory zones when in the case.
Audio Codecs: AAC, SBC and LHDC
The sound quality depends on how the audio data is compressed and transmitted over the air. Xiaomi Air 2 supports a set of modern codecs, including basic SBC and AAC, as well as advanced LHDC (depending on the specific modification and region).
The SBC (Sub-band Coding) codec is a mandatory standard for all Bluetooth devices. It provides acceptable quality but has a high compression ratio, which can lead to loss in complex music compositions. AAC (Advanced Audio Coding) is used predominantly in Apple devices and many Android smartphones, offering better quality at the same bitrate.
The most interesting is the codec support. LHDC (Low Latency High Definition Audio Codec is a high-resolution technology that allows you to transmit sound at bitrates to the end of the spectrum. 900 qbit/s and bit-s 24 bit/96 To work in this mode, both the headphones and the smartphone must support this standard.
Why is it that the sound is worse on Android?
A comparison of the main characteristics of codecs is presented in the table below:
| Parameter | SBC | AAC | LHDC |
|---|---|---|---|
| Bitrate (max) | 328 kbps | 256 kbps | 900 kbps |
| Frequency of sampling | up to 48 kHz | up to 48 kHz | up to 96 kHz |
| Delay (Latency) | Tall. | Medium | Low (up to 40 ms) |
| Compatibility | 100% devices | iOS, Android | Flagships Xiaomi, Huawei |
Using a better codec requires more power, so battery life with activated LHDC can be slightly less than with SBC.
Microphone architecture and noise reduction system
The system of two microphones on each earpiece is responsible for transmitting your voice during a conversation, and it's not just duplication, it's a complex beamforming scheme, one microphone at the bottom of the leg and it's pointing at the user's voice, and the other one at the outside to capture ambient noise.
The built-in digital signal processing (DSP) processor analyzes the streams from both microphones in real time. The algorithm highlights the frequencies of the human voice and suppresses background low-frequency hums, such as wind, traffic or air conditioning noise.
The efficiency of the system depends on the density of the earphone to the ear, and if the fit is leaky, external noise penetrates directly to the bottom microphone, which confuses the noise reduction algorithms.
⚠️ Warning: When talking in high winds, try to cover the lower part of the headphone with your palm or collar of clothing, as wind noise is difficult to filter out software.
It’s also worth mentioning the feature (bone conduction) in some versions, although the Air 2 uses classic air transmission. the Infrared sensor can automatically put a hold call if you remove the earphone from your ear during a conversation.
Logic of the charging case and indication
The charge case is not just a battery box, it's a smart device that controls the charge cycles. Inside the case, there's a power controller that determines the type of device connected and delivers the current you need. The headphones themselves use low current, and the larger one to charge the case from the grid.
The status is shown through LEDs. The white light on the front panel tells you the status: flashing when charging, constant glow at full charge and a special pairing mode. Inside the case, at the bottom of each compartment, there are also LEDs showing the charge status of a particular earphone.
☑️ Case check
There is an important aspect of the controller: if the headphones have not been used for a certain time, the case can go into deep sleep mode to save energy, in which case, the indicator may not light up immediately when the first extraction is performed, it will take several seconds to “wake up” the circuit.
Charging is done via the Type-C port on the back of the case. The fast charging standard is supported, but the use of too powerful adapters (for example, from laptops) is not recommended, since built-in protection can limit current, but heating the elements is still possible.
Energy saving and auto-switching algorithms
The autonomy of the Xiaomi Air 2 is achieved not only by the capacity of the batteries, but also by aggressive energy saving algorithms. The microcontroller constantly monitors the state of activity. If the audio stream is not transmitted within 5-10 minutes, the headphones automatically go into deep sleep mode.
There's also a function to auto-turn off when you take out one earbud and put it on the table, and it won't turn off immediately, but after a certain time (usually 15-20 minutes) it will shut down so that it doesn't go to waste.
Factors affecting the discharge rate:
- 🔊 Volume level – the louder the sound, the greater the amplitude of the membrane and the higher the power consumption.
- 📶 Communication quality – finding lost signal or working at the limit range makes the Bluetooth module work at maximum power.
- 🌡 Ambient temperature – Lithium polymer batteries lose capacity in the cold and degrade faster in the heat.
To extend the battery life, it is recommended not to discharge the headphones "to zero" regularly.The optimal range for storage is 40-60% of the charge, unless you plan to use them for a long time.
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The combination of optical sensors, gyroscope and smart power controller allows Xiaomi Air 2 to work up to 5 hours in active mode and up to 24 hours with the case.