We've written about Bluetooth technology in detail, including audio applications, common information, and the HFP, HSP, and A2DP profiles, as well as the aptX HD that audiophiles love. Several projects classified as high-profile in consumer electronics at the time, glittering with marketing and advertising, have fallen by the wayside. On the contrary, Bluetooth is here to stay! Let's see what the latest achievements of this technology, developed since 1993, have been in modern times.
Bluetooth, which already replaces cables, has proven to be much more convenient and loyal for users. Updates are also provided with appreciable regularity. In previous years, Bluetooth 4.2 appeared on the market and had differences, namely increased data transfer speed and privacy compared to the widely used Bluetooth 4.1 in late 2013.
The Bluetooth 5.0 standard is now popular around the world. This technology has an increased range, and the data transfer rate has also increased significantly. In addition, this technology comes with better noise immunity than previous versions. All of this has brought audio transmission technology up to date.
It is expected that by next year, 14 billion devices in use will be equipped with this technology. One of the reasons for the great popularity of Bluetooth is its backward compatibility, meaning that if your smartphone supports Bluetooth 5.0, while the version of Bluetooth technology in your headphones is 4.2, and they interact with each other, there will be no problems with connection and use.
1. Benefits of Bluetooth 5.0 Technology
Let’s start by looking at the evolution of the Bluetooth Low Energy standard Bluetooth 5.0, which is finally being used by audio devices. This implies that your digital devices, including smartphones and headphones, can run longer on a single battery charge while connected with Bluetooth. Another feature of Bluetooth 5.0 that stands out is the Dual Audio function, which allows you to play music simultaneously on two connected devices. For example, listening to the same piece of music with your loved one is quite romantic.
Bluetooth 5.0 has documented its ability to operate up to 240 meters away. The public is using these features as they become available. The developers of this technology call the documented feature a great achievement, which was made possible “after years of repeated research and testing,” which is certainly remarkable.
1.1 High Data Transfer Rates - Bluetooth 5.0
The most advantageous feature of Bluetooth 5.0 technology is its ability to operate with data transfer rates as high as 2 Megabytes per second (MB/s), twice the speed of Bluetooth 4.0. What are the concrete achievements obtained with this technology?
The answer is very simple: the ability to enjoy uncompressed high-resolution audio files, lower battery consumption and longer operation range! In addition, the transmission rate is able to bring you a much faster data transfer rate than CD. The high data transfer on Bluetooth 5.0 is more advantageous for consuming content that requires high bandwidth, such as HD or FHD videos, while the bitrate of a CD is much higher (1411 Kbps vs LDAC 990 Kbps), which provides much better sound quality than music played on Bluetooth.
Bit rate refers to the number of bits or the amount of data processed in a given amount of time. In audio, it is usually kilobits per second. For example, audio files with a bit rate of 256 kilobits per second mean that each second of the song contains 256 kilobytes of data. The higher the bit rate of the song, the more space it will take up on your computer, but it will also give you a better listening experience.
In audio and video streaming formats (such as MPEG and MP3) that use lossy compression, the “bit rate” parameter expresses the degree of compression of the stream and therefore determines the size of the channel for which the data stream is compressed. Audio and video bit rates are most commonly measured in kilobits per second (kilobits per second, kbps), less frequently in megabits per second (video only).
Audio CDs tend to take up a lot of space, so it has become common to compress these files to fit more music on your hard drive. This is where “lossless” and “lossy” formats come in.
2. AptX Family: Adaptive, Low Latency, and aptX HD
From this moment, Qualcomm aptX HD appears on the scene. It was designed with the ever-increasing demand of music lovers for high-quality sound in mind. This advanced codec supports 24-bit Bluetooth music quality with frequencies as high as 48 kHz. The signal-to-noise ratio is another great achievement and reaches 129 dB. This value is unique in that it is not found on any modern reference level DAC.
The University of Salford conducted independent tests, and a quote of the results can be found on the developers’ website, which states that after analyzing the test results of 24 test-takers, it can be concluded that the test participants were not able to consistently detect the difference between 24-bit/96 kHz encoded and decoded 24-bit/48 kHz aptX HD sound.
Now, let’s look at and analyze the implementation of aptX HD on the Qualcomm SOC CSR8675 audio chipset as an example. It can process 24-bit audio signals end-to-end, and, compared to its predecessors, it can handle deeper digital signals. Thanks to sequential encoding and decoding during the transmission/reception process, a reduction in the signal-to-noise ratio is also achieved. This technology also claims a reduction in distortion, especially in the 10-20 kHz range.
The chipset is equipped with a programmable 80 MHz RISX processor. The integrated 24-bit Kalimba DSP processor does the audio signal processing. A 24-bit stereo DAC is also on board and has a range frequency of up to 96 kHz. A 24-bit stereo DAC, which is also on board, works to implement sample rates up to 192 kHz while the margin is set for the parameters.
2.1 Qualcomm aptX Adaptive Audio Codec
The developers of Qualcomm chipset technology did not stop there and also proposed the aptX adaptive audio codec. It has a lower delay in dynamic mode, which is considered perfect for headphones used during games. It also offers an adjustable bit rate, which can be matched to the data transfer rate to ensure seamless communication. Upon its release, Qualcomm touted aptX Adaptive Audio as a tuned audio codec that is dynamic in nature and backward compatible with aptX and aptX HD.
According to the company’s claims, the codec is designed to automatically tunes itself to ensure optimal sound quality. The aptX Adaptive is capable of operating at two-bit rates, namely 276 and 420 Kbps. In its second version, based on algorithms using advanced coding, it even lags behind aptX HD in some parameters, including the signal-to-noise ratio, but not by much.
2.2 Qualcomm aptX Low Latency
Another Qualcomm codec is aptX Low Latency, which uses Bluetooth 5.0 technology for low latency audio. The end-to-end delay provided by this technology when transmitting via Bluetooth is no more than 32 ms.
Delays for normal Bluetooth stereo can vary considerably and depend on the implementation and buffering of the system. Nevertheless, they are normally larger and more noticeable. Specifically, using Bluetooth devices to connect wireless headphones to the TV was almost impossible. In fact, +40 ms to -60 ms is the recommended delay for synchronizing audio and video in television broadcasts.
For concerts and studio feedback systems, the most feasible and technical solution should be between 20 and 30 ms. Low-latency aptX comes close and offers the latest features, especially for the gaming community. We can no longer feel the 32 ms delay.
3. Bluetooth MIDI & Video
More than ever, the capabilities and features of Bluetooth 5.0 have become the possessed belongings of the genuine lovers of high-quality music. But this does not imply that advancements in Bluetooth technology have not entered into the other domains of multimedia entertainment.
On the site of the Bluetooth SIG organization, which is involved in the development of technology, you can find a section that has the existing standard. You can also find the A / V remote control profile – AVRP, HID, the standard GAVDP audio/video profile (which is in existence since 2012), the user interface device profile, the extended A2DP audio distribution profile version 1.3.2 and many other promising features.
Attention should also be paid to the Bluetooth MIDI technology, which is also widely known as Bluetooth SMART and is distributed amongst the MIDI community. The Bluetooth MIDI standard was only recently introduced in 2017 and allowed MIDI messages to be transmitted over Bluetooth with a relatively low latency of 10-20 ms (4 ms for conventional USB).
This technology is supported by all modern operating systems, mainly iOS from version 8, Android from version 6 and Windows 10, and Mac OS from High Sierra. The technology works in an ingenious way. The best part is that you can connect this wireless controller to your iPhone and play synths with Garage Band.
These BLE technologies have provided freedom for new experiences and given the margin for creativity, you can even use it to monitor the status of plant growth chambers. What we can expect the Bluetooth technology to provide us in the near future with its development will become evident soon with time.