In this era of rapid development of science and technology, wireless smart devices are emerging, the purpose is to bring convenience to our lives. Bluetooth technology was originally developed by telecoms giant Ericsson
The company was founded in 1994 as an alternative to the RS232 data line. No wire binding, a variety of devices connected, mobile computer data transmission, computer outside
printers, appliances, headphones, cameras, cars and more.
Bluetooth is a wireless technology standard that uses UHF radio waves in the ISM band from 2.4 to 2.485GHz to enable short-range connections of devices. Traditional wired headphones rely on wire to transmit audio data, Bluetooth headsetist is transmitted by radio waves, then many people will have a question, Bluetooth headset listening to music will affect the sound quality?
The difference between the construction of Bluetooth headsetand and the wired headset is that there is an additional Bluetooth module and battery, removing the cable. The Bluetooth protocol has evolved and upgraded several versions, and in the previous version of the Bluetooth protocol, due to the limitations of transmission efficiency, it is not able to achieve the transmission speed required for music listening, so it is often used for communication and phone calls.
Putting aside the horn unit, the most important is the Bluetooth chip, which determines the quality of the transmission quality, a good Bluetooth chip can support better audio decoding technology. Our factory mainly uses Qualcomm CSR chip, supports two-channel stereo codec, has Apt-x-enabled headphone products, high-quality transmission of low distortion.
At present, the popular high-quality Bluetooth audio compression algorithms are aptX/aptX-HD, LDAC, LHDC and so on. Among them, aptX is a technology introduced by CSR, which was acquired by Qualcomm and became a proprietary technology for Qualcomm chips.
To understand the sound quality of Bluetooth headsets, we need to understand the following concepts first:
(1) A2DP: is a Bluetooth audio transmission protocol, using the chip in the headset to stack data, to achieve high resolution of sound. Most Bluetooth headsets on the market are using the A2DP transmission protocol.
(2) apt-x: is an audio digital compression algorithm, mainly used in the professional audio field, providing high-quality audio, some high-quality headphones will support this algorithm
(3) LDAC: High-quality audio codec developed by Sony, Qualcomm's apt-xhd as the main competitor.
(4) LHDC: High-quality Bluetooth audio codec protocol.
(5) SBC: General audio encoding format, Bluetooth transmission does not support AAC, aptx when the use of SBC transmission, now 80% of this format.
(6) AAC, audio encoding format, when Bluetooth support AAC format files, mobile phones also support AAC transmission, the sound quality is much better than SBC, ordinary people listen to this difference, the current Qualcomm CSR mainstream chips are supporting AAC format transmission.
Although the Bluetooth version is now limited by A2DP's transmission capacity (SBC can only provide up to 328Kbit/s bandwidth at 44.1Khz), audio cannot be 100 percent restored via Bluetooth transmission (CD sound quality requires 1.41Mbit/s). But if you don't use SBCs, but use more advanced compression techniques that allow audio to be compressed and then transmitted over A2DP, the sound quality can be greatly improved.
The structure of the headset and the environment, and the distance between the Bluetooth devices, can affect the sound quality of the Bluetooth signal.
