How Bluetooth Headphones Work Part 3


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How Bluetooth Headphones Work Part 3

aptX BlueTooth

What is aptX, the savior of Bluetooth sound quality

bluetooth aptx

 

Let’s take a look: if you compare a Bluetooth headset to a person, the Bluetooth chip is like your heart and aptX technology is like your eloquence. Whether the transmitted sound is smooth and clear, so that the listener can know what you mean is an important indicator.

With the chestnuts finished, let’s get back to the topic: What is aptX anyway? Now, let’s take a look at it from a technical point of view.

There is a word involved in Bluetooth transmission technology called “bit rate”, which is the number of bits transmitted per second, and the unit is bps (bits per second). In the case of transmitting the same audio file, the higher the bit rate, the faster the data transmission speed and the shorter the time required. There should be “chestnuts” here, like when Yao Ming was practicing, he had 100 basketballs at A, and he had to throw them into the basket at B. Under the premise of making all the shots, Yao Ming would take more basketballs each . (Bit rate) and the more basketballs (bit rate) you put in, the shorter the total time required.

But for Bluetooth technology, because it is limited by the maximum bandwidth available in transmission, it is not always suitable for transmitting high-quality audio.

For this reason, Bluetooth “guardian angel” -aptX technology was born. It recodes and decodes the audio to be transmitted, significantly reducing the bit rate, without affecting the sound quality and without the transmission delay, which makes the Bluetooth stereo listening experience a revolutionary leap. So with aptX, you can enjoy pure wireless audio with CD-level sound quality anytime, anywhere.


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How Bluetooth Headphones Work Part 2

How Bluetooth Headphones Work Part 2

Bluetooth Aptx

Introduction to Common Abbreviations in English

aptX Bluetooth

NFC – Near field communication technology, Bluetooth headphones with this function can be quickly paired and connected by touching the playback device.

AAC: The technology provided by Dolby Laboratories is a high compression encoding algorithm. There is a lot of AAC audio in Apple Music and the sound quality is better than MP3 at the same bit rate. The iPhone will use AAC encoding for Bluetooth streaming. .

AptX – Qualcomm’s leading encoding technology, which is more efficient than traditional Bluetooth encoding and preserves more details in the sound. Most newer Android phones are equipped with AptX, but Bluetooth headsets must also be AptX-compatible to be effective.

LDAC – A Bluetooth transmission technology developed by Sony itself, which can transmit 3 times normal Bluetooth data and perform lossless music playback with Bluetooth, but only Sony devices support this technology.

Simply put, in terms of bit rate, AAC “AptX” LDAC. From the point of view of the audio source, if the player plays lossless music, the actual listening experience is AAC “AptX” LDAC, but since most users use network players such as NetEase Cloud or QQ Music, the source audio is mainly 128K. or 320K MP3, so there is no obvious difference in hearing between these encoding modes.

How to check if the phone supports aptx

Better to check the supported devices on the aptx official website.

APTX is a compressed streaming format that, while also lossy, can stream audio files with higher bit rates.

From a mobile phone point of view, APTX support requires mobile CPU support, but because this technology is paid, not all mobile phones have it. For example, Qualcomm Snapdragon 820 and 835 support APTX, but use Snapdragon 820. Mi 5 is Not Supported. Under normal circumstances, you can check for the APTX logo on the phone’s packaging:

Otherwise, you can call the after-sales consultation.

Of course, the safest way is to log into the APTX official website for inquiries. If submitting a link is not convenient for you, please use the official Baidu website. Go to the upper right corner of the official website and select Chinese, click Product search filter, the first is the brand, the brands in this list are compatible with aptx products (the list is sorted by English AZ , arranged vertically from left to right), the second One is the type of product: computers, mobile phones, headphones, speakers, etc. There are many types of products, the third is the aptx type, there are three types that are used in different fields. Please find your own brand and model of mobile phone, if it is not shown, it is not supported.

How Bluetooth Headphones Work

How Bluetooth Headphones Work

Bluetooth Headphones

The decoder chip of the mobile phone decodes music files such as MP3, generates a digital signal and sends it to the Bluetooth headphones via Bluetooth;

Bluetooth Headphones

The Bluetooth headset receives the digital signal and converts it to an analog signal that the human ear can understand through the digital-to-analog conversion chip inside the Bluetooth headset;

To amplify the analog signal, you must use the signal amplifier chip inside the earphone;

The headphone unit receives the amplified signal and makes a sound, and at this time, the ear hears the sound of music.

Do Bluetooth headphones ring?

However, the sound quality of Bluetooth headphones has long been criticized. The saying “Bluetooth headphones hear a sound” often circulates in the enthusiast circle. There are two main reasons for this:

When Bluetooth transmits audio data, it performs lossy compression on the audio, which loses sound quality;

Digital-to-analog conversion and amplification is done inside the Bluetooth headset. It’s hard to do both at the same time in such a small size, so for the sake of portability and price, sound quality is sacrificed even more.

The second point is the main reason. After understanding the principle of Bluetooth headphones, we know that for Bluetooth headphones to work properly, it is necessary to install batteries, Bluetooth modules, digital to analog conversion circuits, amplifier circuits, headphones. units, etc. in the headphone shell Series components, testing the manufacturer’s product design capabilities and comprehensive technical robustness. However, accomplishing this step only satisfied the need to “express”. If you want good sound, you should also tune in. This link should check the specific sound performance of the headphones with different materials, different diaphragms and different cables. In short, it is a more complicated process and the main R&D cost of the manufacturer.

Simply put, Bluetooth headphones are the product of compromise thinking, in order to get rid of the headphone cable shackles and reduce some of the sound quality. However, from today’s point of view, the sound quality of Bluetooth headphones made by traditional headphone manufacturers is generally better (of course, the price is also more expensive), which can meet the needs of most of users in terms of the appreciation of music, and the low-priced Bluetooth headphones produced by small manufacturers are in fact can only “hear” it.

What you need to know about listening on Bluetooth headphones

What you need to know about listening on Bluetooth headphones

Bluetooth

Harald Bluetooth IBluetooth is the wireless transmission of data between two devices in a short distance. This is done using radio waves (WPAN).

Bluetooth

Few know that the name of Bluetooth technology comes from the name of the Danish king Harald Bluetooth I (958 AD). It was he who brought together parts of Norway and Denmark. And the Bluetooth symbol itself denotes the Scandinavian runes B and H.

So to transfer music via Bluetooth 3 factors are required:

Sampling frequency (kHz): the higher the sampling frequency, the clearer the sound can be transmitted (closer to digital). Distortion in sound is reduced and the audible frequency range is widened.

Sampling depth (bits): The higher the sampling depth, the higher the resolution of the music. Dynamics increases as the range between soft and loud sounds increases. In this way, it is possible to obtain more subtle sound levels and tonal nuances.

Bit rate (kbps) – This is the connection speed at which music audio data is transmitted from the device to the headphones. However this is not entirely true. More precisely, this value indicates the possible size of the amount of data transmitted at a given time. The higher the baud rate with the Bluetooth headset, the more data (at the same time) the device can transfer. Therefore, the audible sound is greatly improved.Better Bluetooth audio: what aptX, aptX HD and LDAC are all about

What do the abbreviations aptX, pptx HD, and LDAC mean?
These abbreviations are for Bluetooth codecs and mainly describe various transmission parameters. They differ in sample rate, sample depth, and bit rate. Android 8.0 devices support these audio codecs and you can enjoy better sound quality.

atpX is the slowest option for wireless music streaming. This technology provides a maximum bit rate of 352 kilobits per second at a sample rate of 48 kHz and a sample depth of 16 bits. The analog signal is read 48,000 times per second and stored with 16 bits. In principle, these are solid numbers. In comparison, a CD is read and stored with identical parameters. However, relatively slow streaming results in a nearly 50% loss in audio quality. So the sampling depth is only 8 bit, which is related to the resolution of the music.

The AtpX HD also has a sample rate of 48 kHz, but the digital signal is stored at 24 bits. The dynamic range is increased, resulting in higher quality sound. The use of LPCM (Linear Pulse Code Modulation) results in lossless data transmission from analog to digital signal. The sound is thus clearer.

PCM is a modulation technique that converts an analog signal into digital. The CD receives the analog sound waves from the music recording.

Best Bluetooth audio: what aptX, aptX HD, and LDAC are all about
Sony H. EAR on wireless
It is not yet known to what extent the bit rate in this codec is adapted only for the best sound transmission in headphones.

Sony’s LDAC Bluetooth codec is the best and fastest of the three wireless audio capabilities.

At data rates of less than 1 Mbps at a sampling rate (96 kHz) and a sampling depth of 24 bits, almost CD quality is achieved.