It’s spring time again. The happiest time every day is on my way to work with my bluetooth headset, listening to my favorite songs and riding my beloved electric donkey. If one day the earphone is out of power or not wearing earphone 🎧, it feels lacking what.
Here are some of the most headphone manipulations I do every day:
In current electronic devices, bluetooth protocol is becoming more and more common in device use, such as airpods, stereos, mice and cars. We all know that Bluetooth is a communication protocol, so how does a mobile phone connect to our headphones and deliver music to our ears? Let me talk about it today!
Introduction and origin of Bluetooth
Bluetooth is a wireless communication technology standard that enables fixed and mobile devices to exchange data over short distances to form a personal LAN (PAN). It uses short-wave high-frequency (UHF) radio waves to communicate over the ISM band of 2.4 to 2.485GHz. The technology was developed by telecommunications firm Ericsson in 1994. It was originally designed to create a wireless communications alternative to RS-232 data lines. It can link multiple devices and overcome synchronization issues.
Here appeared a professional term: UHF(ultra high frequency), here we also need to give you popular science under the radio related knowledge.
Radio waves, also known as Radio, Radio, etc., are electromagnetic waves whose wavelength is longer than infrared in the electromagnetic wave. Radio waves range in frequency from 300GHZ to 3kHz, but there are definitions that classify any radio wave above 1GHz or 3GHz as microwave. Like other electromagnetic waves, radio waves travel at the speed of light. Radio waves in nature are mainly formed by lightning or cosmic objects.
Specific division is shown in the figure below:
The Bluetooth standards are maintained by the Bluetooth Technology Alliance (SIG), which has more than 30,000 members in telecommunications, computing, networking and consumer electronics.
The word “Bluetooth” is an Anglicization of the Scandinavian words Blatand/Blatann. The word comes from the 10th century Danish and Norwegian king Harald Blatand (Danish: Harald Blatand Gormsen), who borrowed the king’s nickname Blatand as his name, which translated directly into Chinese as Bluetooth (bla = blue, tand = tooth). In 2006, the Bluetooth Technology Alliance organization has changed the global Chinese translation of the literal translation of “Bluetooth”, and registered as the organization’s registered trademark.
Harald has united Norway and Denmark, which were divided by religious wars and territorial disputes, so the team behind Bluetooth expected the new technology to integrate the standards of various zetcom brands. The symbol of Bluetooth is the Ruane alphabet
How does a Bluetooth connection work
Bluetooth devices operate on 79 different frequencies across the 2.45ghz radio spectrum. When two devices want to connect — say, a smartphone connected to AirPods Pro — they randomly choose one of 79 channels, or try another if another pair of nearby devices already occupy another channel.
Typically, a password created by the device is required to connect two Bluetooth products together. When a smartphone is connected to a car, for example, both will display a short code on its display. If both sides display the same code, the connection can continue. Interestingly, I’ve never seen a pair of devices display different code from each other.
Paired devices once paired will remember each other unless you let them forget. That’s why your phone connects (or at least should) automatically every time you get in the car, because the two devices know and trust each other.
How do the earphones sound
Modulation and transmitter
Every cell phone has a radio system with a transmitter. A radio transmitter, with alternating current, passes through an oscillator to become a high-frequency alternating current, producing an electromagnetic field through which an infinite wave can be generated. Like magnets, radio waves repel each other and attract each other. Electrons of the same kind repel each other, so when a radio wave is emitted, it pushes the wave in front of it forward, and when a continuous wave is emitted, it travels through the air.
Receiver and demodulation
Electromagnetic waves can be picked up by tuned antennas. The antenna can antagonize some of the electromagnetic energy into a resonant current in the circuit. The receiver can demodulate the current and convert it into a usable signal. Receivers are also tuned to pick up signals from certain bands and reject signals from others.
vibration
We all know that sound is generated by vibration. Headphones work in the same way as speakers: they convert the input audio signal into mechanical vibration, so that you can hear beautiful music in headphones
In high school, we learned about Faraday induction: a change in magnetic flux produces an electric current. For example, when a part of the conductor of a closed circuit moves in the magnetic field to cut the magnetic induction line, it will produce a current, which is simply magnetic generation.
And vice versa, electric currents also create magnetic fields. The working principle of earphones is that the change of electric current produces a changing magnetic field, which vibrates with the diaphragm of the magnet and produces sound
Inside the headphones, there are two magnets. One is the strong magnetic magnet shown in the picture below. It is a permanent magnet, fixed to the frame of the earphone, which is stuck firmly and cannot move. The other is connected to the diaphragm voice coil, is an electromagnet, when the electricity will produce magnetic, is movable.
The sound is caused by the vibration of the air pushed by the diaphragm. When the audio current passes through the earphone wire and flows through the red voice coil in the earphone below, a changing magnetic field will be generated. This magnetic field will interact with the permanent magnet material fixed in the earphone, and the stress on the voice coil will generate movement of different amplitudes, thus driving the diaphragm to vibrate and producing a changing sound. That’s how speakers work!
advantages
Wireless data transmission
One of the main advantages of Bluetooth is that it allows devices to transmit data wirelessly. This translates into more specific advantages, including wireless connectivity or “pairing” of devices to create wireless personal lans or WPANS, wireless Internet connectivity and wireless synchronization, and the ease of sending and/or receiving files without the hassle of carrying and carrying them. Use cable or other hardware interface technology, such as USB standard or Thunderbolt technology.
Through bluetooth, please note, other applications include wireless connection between equipment compatible with the other equipment of the remote control, within a certain distance is used to locate and identify the object of real time positioning system, used to prevent devices such as smart phones are stolen or lost personal safety, as well as the use of bluetooth medical equipment for health monitoring and recording.
Extensive availability and accessibility
The many applications of Bluetooth demonstrate its wide and almost universal availability. Most laptops and other mobile devices, such as smartphones and tablets, come with built-in Bluetooth hardware. For PCS that do not have the required hardware components, purchasing and using bluetooth adapters will enable them to communicate with Bluetooth-enabled devices.
As Bluetooth seems to have become a standard feature of modern computers, especially laptops and mobile devices, complementary devices have been developed and sold. These include wireless speakers and headphones, smart devices like smartwatches and other wearable technology that can monitor activity, and bluetooth-enabled smart home appliances and office equipment.
Ease of use brings convenience
Pairing the device with the built-in Bluetooth radio is easy. Establish communication between Bluetooth-enabled devices without installing additional software or drivers. There is also no strict setup process for two devices to communicate.
As long as bluetooth-enabled radio devices are in range and kept within range, the technology makes it easy for each other to find enabled devices, simplifying the whole pairing process. In addition, the technology includes protocols for identifying services using service discovery protocols and universal unique identifiers to list specific services or functions for specific devices. These protocols make it easy for another device to identify and display the name and category of the device to be paired with, as well as its services or functions and technical information.
Energy efficiency
Bluetooth technology further enhances the benefits and convenience of wireless data transmission due to its high energy efficiency. This is especially true for low-power Bluetooth or BLE standards. BLE’s ultra-low power requirements make it ideal for small devices (including wearable technology) where minimal battery life requirements and small size are key design and engineering considerations.
The latest version of the technology, called Bluetooth 4.0, is also more power-efficient than Bluetooth 3.0. The new specification has the same BLE technology and classic Bluetooth standards as those in the older Bluetooth specification, thus allowing dual mode to take advantage of energy efficiency and faster data transfer rates.