As the name implies, a "wireless remote control" is a device used to remotely control a machine. Modern remote controllers are mainly composed of integrated circuit boards and buttons for generating different information.

Nowadays, wireless remote control has been more and more used in our daily life, which has brought great convenience to people. With the development of science and technology, wireless remote control has also expanded to many types. In a word, there are two kinds of common ones, one is the infrared remote control mode commonly used in household appliances, and the other is the radio frequency remote control mode commonly used in burglar alarm devices, door and window remote control, car remote control and so on.

[Edit this paragraph] History

It is impossible to test who invented the first remote control. But one of the earliest remote controllers was developed by an inventor named nikola tesla (1856- 1943) in 1898 (U.S. Pat. No.6 13809), which is called "Method and device for controlling moving vehicles or vehicle mechanisms".

[Edit this paragraph] Types of wireless remote controllers

Infrared remote controller

The IR Remote Control is a remote control device which uses the near infrared ray with the wavelength of 0.76 ~ 1.5μ m to emit control signals.

The commonly used infrared remote control system is generally divided into two parts: transmitting and receiving.

The main component of the transmitting part is infrared light emitting diode. It is actually a special kind of light emitting diode. Because its internal material is different from ordinary light-emitting diodes, when a certain voltage is applied across it, it emits infrared rays instead of visible light.

At present, the widely used infrared light-emitting diode emits infrared light with a wavelength of about 940nm, and its appearance is the same as that of ordinary light-emitting diodes, but its color is different.

The main components of the receiving part are infrared receiving diodes, which are generally round and square. In practical application, it is necessary to apply reverse bias to the infrared receiving diode to make it work normally, that is, the infrared receiving diode is used in reverse when it is applied in the circuit to obtain higher sensitivity.

Because the emission power of infrared light emitting diode is generally small (about 100mW), the signal received by infrared receiving diode is weak, so it is necessary to add high gain amplifier circuit. In recent years, most of them have adopted finished infrared receivers.

There are two kinds of packaging for finished infrared receiver: one is metal shield; One is plastic packaging. There are three pins, namely, positive power supply (VDD), negative power supply (GND) and data output (VOUT). Different types of infrared receivers have different pin arrangements. Please refer to the manufacturer's instructions. The advantage of the finished infrared receiver is that it does not need complicated debugging and shell shielding, and it is very convenient to use as a triode. But pay attention to the carrier frequency of the finished infrared receiver when using it.

The common carrier frequency of infrared remote control is 38kHz, which is determined by the 455kHz crystal oscillator used by the transmitter. At the transmitter, the crystal oscillator is divided by integer, and the frequency division coefficient is generally 12, so 455kHz÷ 12≈37.9 kHz≈38kHz. Some remote control systems use 36kHz, 40kHz and 56kHz, which are generally determined by the oscillation frequency of the crystal oscillator at the transmitter.

The characteristic of infrared remote control is that it does not affect the surrounding environment and interfere with other electrical equipment. Because you can't go through the wall, the household appliances in different rooms can use the universal remote control without interfering with each other; The circuit debugging is simple, as long as the given circuit is connected correctly, it can be put into operation without any debugging; Easy coding and decoding, multi-channel remote control. Therefore, infrared remote control has been widely used in household appliances and indoor close-range (less than 10 meter) remote control.

Radio remote controller

The RF remote controller of the transmitter and receiver controller module is a remote control device, which uses radio signals to control various remote control mechanisms. After these signals are received by the remote receiving equipment, they can instruct or drive other corresponding mechanical or electronic equipment to complete various operations, such as closing the circuit, moving the handle, starting the motor, etc., and then these machines will carry out the required operations. As a complementary remote controller with infrared remote controller, it has been widely used in garage doors, electric doors, road brake remote control, burglar alarm, industrial control, wireless smart home and other fields.

The commonly used radio remote control system is generally divided into two parts: transmitting and receiving.

The transmitting part is generally divided into two types: remote controller and transmitting module. The remote controller and the remote control module are in use mode, and the remote controller can be used independently as a whole machine, and the external lead wire is provided with a connector; The remote control module is used as an element in the circuit and is applied according to its pin definition. The advantages of using remote control module are seamless connection with application circuit, small size, low price and making the best use of everything, but users must really understand the circuit principle, otherwise it is convenient to use remote control.

Generally speaking, the receiving part is also divided into two types, superheterodyne and super-regenerative receiving mode. Super regenerative demodulation circuit is also called super regenerative detection circuit, which is actually a regenerative detection circuit working in intermittent oscillation state. The superheterodyne demodulation circuit is the same as the superheterodyne radio. It is equipped with a local oscillator circuit to generate an oscillation signal, which is mixed with the received carrier frequency signal to obtain an intermediate frequency (generally 465kHz) signal, and the data signal is demodulated by intermediate frequency amplification and detection. Because the carrier frequency is fixed, its circuit is simpler than that of a radio. The superheterodyne receiver has the advantages of stability, high sensitivity and strong anti-interference ability. Super regenerative receiver is small and cheap.

The carrier frequency commonly used for radio remote control is 3 15mHz or 433mHz, and the remote controller uses the open frequency band specified by the state. In this frequency band, if the transmission power is less than 10mW, the coverage area is less than 100m or not beyond the scope of the unit, it can be used free of charge without the approval of the Radio Management Committee. China's open frequency band is 3 15mHz, while Europe, America and other countries stipulate that it is 433mHz, so products exported to these countries should use 433mHz remote controllers.

There are two commonly used coding methods for radio remote control, namely fixed code and rolling code. Rolling code is an upgraded product of fixed code. At present, all occasions with confidentiality requirements adopt rolling coding.

The rolling code coding method has the following advantages:

1, with strong confidentiality, automatically changes the code after each transmission, and others cannot use the "code checker" to obtain the address code;

2. The coding capacity is large, the number of address codes exceeds 654.38+10,000 groups, and the probability of "duplicate codes" in use is extremely small;

3. Code alignment is easy. The rolling code has the functions of learning and storing, and can be aligned at the user's site without soldering iron. Moreover, a receiver can learn as many as 14 different transmitters, which is very flexible to use.

4. The error code is very small. Due to the advantages of coding, the misoperation of the receiver is almost zero without receiving the local code.

The coding capacity of fixed codes is only 656 1, and the probability of duplicate codes is extremely high. Its code value can be seen through solder joint connection or obtained by using the "code detector" on site, so it is not confidential. It is mainly used in occasions where confidentiality requirements are not high, and it has been widely used because of its low price.

The difference between infrared remote control and radio frequency remote control is that infrared remote control and wireless remote control are different carriers. Infrared remote control uses infrared to transmit control signals, which is characterized by directionality and no obstruction, and the distance from electromagnetic interference is not more than 7 meters. TV remote control is infrared remote control. Radio remote controller uses radio waves to transmit control signals, which is characterized by directionality, no "face-to-face" control, long distance (up to tens of meters or even kilometers) and easy to be disturbed by electromagnetic interference. In industrial control and other fields that need long-distance penetration or non-directional control, it is easier to solve it by radio remote control.

[Edit this paragraph] Influencing factors of wireless remote control distance

The main factors affecting the radio remote control distance of the RF remote controller are as follows:

1, transmission power: if the transmission power is large, the distance is long, but it consumes a lot of power and is easily disturbed;

2. Receiving sensitivity: it improves the receiving sensitivity of the receiver and increases the remote control distance, but it is easy to be disturbed and cause misoperation or out of control;

3. Antenna: Linear antennas are used, which are parallel to each other and have long remote control distance, but occupy a large space. When in use, stretching and straightening the antenna can increase the remote control distance;

4. Height: The higher the antenna, the farther the remote control distance, but it is limited by objective conditions;

5. Blocking: At present, the wireless remote controller used is in UHF band specified by the state, and its propagation characteristics are similar to those of light, with linear propagation and small diffraction. If there is a wall between the transmitter and receiver, the remote control distance will be greatly reduced. If it is a reinforced concrete wall, the influence will be greater because of the absorption of electric waves by conductors.

[Edit this paragraph] Application field of industrial wireless remote controller

1, industrial drive: industrial drive is one of the most widely used fields of remote control system, taking Germany as an example, accounting for about 40% of the annual output of remote control system; Especially in metallurgy, automobile manufacturing, paper mills, material warehouses, etc. , almost all new vehicles are equipped with industrial wireless remote control [3];

2. Truck crane: Usually, the remote control system of large truck crane is also equipped with a data feedback device, which can display operating parameters (such as load, boom length, load torque, oil temperature, pressure, angle, etc.). ) On the display screen of the launching system, the operator can monitor the crane according to the displayed data;

3. Concrete pump truck: When the concrete pump truck is working, the console is tens of meters (even hundreds of meters) away from the pouring operation surface. The traditional operation mode needs several people to cooperate to complete, which is inefficient and limits the performance of concrete pump truck. For large pump trucks with long transportation distance and large displacement, the contradiction is more prominent; Using industrial wireless remote controller can give full play to the performance of the whole machine. After the driver of the pump truck drives to the work place, he can use the portable remote control system to operate various actions of the pump truck in turn, such as the left and right rotation of the boom, the amplitude fluctuation of the multi-stage boom and so on. Operators can carry the launching system, stay away from the console of the pump truck, and stand directly near the hose nozzle to control the action of the placing boom and the operation of the concrete pump;

4. Mining machinery: In the case of low visibility in the mine, industrial wireless remote controller with feedback device can be selected to control hydraulic machinery. Even in places with low visibility and bad environment, the drilling operation of heavy rock drill frame can be controlled conveniently. The operator can choose the nearest place to drill instead of staying on the drill console ten meters away from the drilling operation point. The radio control device adopts IP65 protection standard, which is completely suitable for use in humid and salty environment. Greatly improve the safety, comfort and accuracy of operation, save investment and improve efficiency;

5. For special machinery, such as the slag loader in a steel plant, the industrial wireless remote controller is used to remobilize the loader, and 100% simulates the mechanical dynamic performance and operation function of the original crawler loader without changing the existing manual operation mode, so as to achieve the goal of unmanned slag removal. The operator can choose the best visual position freely with the light emitter, and the remote loader can run freely in the slag cleaning operation. The successful application of the remote control loader has eliminated the hidden dangers of accidents such as harsh environment, unclear vision and high temperature slag falling, liberated the operators from the harsh environment, improved the efficiency of slag cleaning, improved the working environment of metallurgical workers and reduced the labor intensity of workers.

6. Building tower crane: In Europe and North America, more than 60% of building rotary tower cranes are controlled by wireless remote control, which not only saves the equipment manufacturing cost (there is no air console), but also fully ensures the safety and reliability and improves the construction efficiency;

7. Other aspects: With the development of industrial wireless remote control technology, industrial wireless remote control has been widely used in loaders, shunting locomotives, hydraulic machinery and port loaders of mobile vehicles, with extremely broad market prospects.