QCC5125 Module HY-BT301C in Automotive DSP Amplifier Audio Solution

For most car hosts, the sound quality of the mobile phone connected to the DSP power amplifier is better than that of the mobile phone directly connected to the car's own speaker.

What’s the difference between mobile phone connect with DSP power amplifier and mobile phone connect with car audio amplifier?

The same is the output of the Bluetooth audio signal from the mobile phone. We found that the sound quality of the mobile phone directly connected to the DSP is much better than that of the mobile phone connected to the car amplifier, and even better than the sound quality of most car amplifier with U disk and CD-ROM.

What factors affect the sound quality when listening to music via Bluetooth?

1.      Bluetooth bandwidth. It mainly affects the transmission efficiency of Bluetooth. The higher the efficiency, the greater the amount of audio information transmitted per unit time, which may bring better sound quality.

2.      The quality of the bluetooth chip. The higher-end Bluetooth chip has better stability and compatibility. The bandwidth of different versions of Bluetooth is only a theoretical value, and the specific situation depends on the status of the transceiver device and the quality of the Bluetooth chip. The current Bluetooth chips of mobile phones are all integrated, such as wifi and GPRS, because they need to meet the requirements of high integration. Most of the Bluetooth of car audio equipment are still independent chips, and even better are independent modules. HYXKIOT’S DSP solution HY-BT301C adopted Qualcomm new chip QCC5125, support APTX HD and LDAC, it’s a BLE+SPP+AUDIO module, supports analog audio, built-in DSP, and supports multiple functions and protocols, such as BLE, SPP, AVRCP, I²S, APTX, LDAC, etc.

3.      Bluetooth encoding, decoding and related circuit design

Many people think that the Bluetooth sound quality is not good because the Bluetooth bandwidth is not enough and it is too far from the wired connection, so the Bluetooth sound quality must be poor.

In the early days, due to the limitations of cost and technology, the Bluetooth version used in the car was low, and the Bluetooth chip used in the host was poor, which did lead to poor Bluetooth music sound quality spread.

The situation is completely different now. In terms of transmission efficiency, the currently commonly used Bluetooth versions for car audio modification equipment are BT4.2, BT5.0 and BT5.1, like HYXKIOT’s DSP application module HY-BT301 is a Bluetooth 5.1 audio+data module.

The information that can be found in the Bluetooth 4.0 version is that the theoretical upper limit of transmission is 3M/s (the actual rate is definitely lower than this), the transmission efficiency of Bluetooth 4.2 is 2.5 times that of Bluetooth 4.0, and the transmission distance has been upgraded (10 meters to 100 meters) and compatibility. The transmission distance of BT5.0 is upgraded to 300 meters, and the transmission rate is twice that of BT4.2. Compared with the Bluetooth 5.0 version, the bandwidth (transmission speed) of Bluetooth 5.1 is increased from 1Mbps to 2Mbps, and the transmission distance is increased by 4 times, that is, the theoretical effective working distance is 300 meters, and the low-power mode is also available.

In fact, the improvement of transmission distance is not significant for car audio, mainly because a larger bandwidth will bring greater potential for sound quality. However, this is the potential brought by the transmission rate, and it is not necessarily all converted into sound quality (for example, some equipment does not support the Bluetooth module with version 5.0 very well, resulting in instability). If you want to convert these potentials into sound quality as much as possible, you need a better Bluetooth chip to provide a more stable connection, as well as better decoding and related circuit design. Qualcomm's QCC5125 chip is the best choice for DSP application at present. These are precisely the advantages of upgraded audio equipment.