At first glance, RF technology has little to do with automotive technology. One is the transmission and reception of signals, and the other is power transmission and speed increase. However, with the development of the economy and the changes in people's attitudes to life, first of all, cars are gradually entering every family, and people are becoming more dependent on cars. Further, in addition to the mobility characteristics and energy-saving of cars, In addition to the various requirements of pollution, the comfort and safety of car driving, as well as the versatility of the car itself, are also demanding and finding solutions on a broad level.
As early as the middle of the last century, electronic technology has found a multi-faceted application in the traditional industry of automobiles. With the popularity of information and entertainment such as radio and television, coupled with the importance of electromagnetic compatibility issues, radio frequency technology has begun to play a pivotal role in the small and complete subsystem of the car.
Electromagnetic compatibility is almost synonymous with safety and reliability
Let's first look at the sources of interference in electromagnetic compatibility issues that are closely related to RF technology. The strongest electromagnetic interference source inside the car is the ignition system, and the electromagnetic signal generated by it has the characteristics of extremely short high-energy pulse. Therefore, the interference is not only high in intensity, but also involves a very wide frequency range; although the hybrid vehicle technology has been extremely For the great development, the interaction between the electric power part and the existing power system still needs in-depth research, and the CISPR standard will gradually publish the corresponding specifications.
In addition, various motors are usually installed in the car, such as wipers, fans, generators, etc. These devices generate interference signals more or less due to the conversion between electromechanical energy; all these interference signals may be used by the car. The various wirings inside are transmitted to other parts of the car in a wired manner, and it is also possible to radiate in the car wirelessly. Due to the diversity and complexity of vehicle construction, it is quite difficult to analyze the specific propagation modes of these interference signals. Usually, they can only be analyzed by actual measurement; in addition, various in-vehicle controllers and monitoring Digital circuits are generally used. Although such circuits have inherent signal characteristics, they are usually measured by actual measurements for the same reasons as above. Otherwise, it is still difficult to perform detailed analysis on the possible interference effects. Not only that, broadcast and television signals, radio waves used in various information and entertainment electronics, etc., are also potential sources of interference.
From the perspective of radio frequency technology, the interference signals generated by the above various types of radiation can be extended to a frequency range of several hundred megahertz (MHz) or higher. Once the intensity reaches a certain value, it is possible to operate other electronic devices. Negative effects; therefore, measuring and limiting interference signals is an important part of automotive electronics.
Measurement interference signals can be divided into: qualitative detection and debugging, pre-test, pre-certification test, and certification test according to the method and environment; and the measurement instruments used are also different; the relevant international standards and each The standards set by the major automobile manufacturing companies can be used as the basis for measurement. In addition to measuring and limiting interference signals, improving the anti-jamming capability of automotive electronic equipment cannot be ignored.
The antenna is undoubtedly inseparable from the car infotainment
Information and entertainment have always been an indispensable part of people's lives. Especially in the current social environment where economics and technology are highly developed, in-vehicle infotainment has gradually become a "necessity of life". In the early 1930s, with the radio With the gradual popularization of broadcasting, the radio has entered the automotive field. People can continue to understand various social activities such as politics, economy, humanities, technology, anecdotes, etc. while driving, and RF engineers are also beginning to explore how to continue Improving the function of the vehicle receiving system, up to now, improving the receiving quality of the car radio for the broadcast signal is still one of the research topics of radio frequency technology.
In many automotive electronic devices, the car radio is not the only RF receiving device. From the perspective of the RF engineer, the complete receiving device is a receiving system composed of a receiver and an antenna. The receiving quality of the RF signal is determined by this receiving system. The two parts (ie, the receiver and the antenna) are determined together, and the characteristics of the antenna directly affect the receiver, which in turn affects the characteristics of the entire receiving system.
Furthermore, the position and structure of the car antenna also determine its receiving characteristics. For a long time, various rod-shaped or whip antennas have been the main structure of the car antenna. The reason is that the structure of the antenna and its relative installation are relatively It is simple, and its receiving characteristics are also better; the basic structure of modern automobiles mostly uses steel materials, and the reflection of electromagnetic waves by metal materials can design a rod antenna whose size is halved and the receiving characteristics are not changed; however, this type of antenna Antennas are usually placed upright, slanted or tilted on the top, front or rear of the car, so they have an impact on the aerodynamic performance and aesthetics of the car; however, the size of the car is much larger than that of mobile electronic devices such as mobile phones. To the high-speed sportiness and beauty of the car, there is not much room for designing the antenna. This is indeed a big challenge for RF engineers.
Since the middle of the last century, semiconductor technology has developed rapidly. RF engineers have introduced transistor amplifiers and microcomputers into the system design of automotive antennas. This epoch-making breakthrough has made it possible to miniaturize and conceal car antennas. Since then, car antennas have gradually integrated. The overall design process of the exterior structure of the car.
Due to the mobility of the car, the signals received by the external wireless system have fading characteristics, that is, the intensity of the signal is randomly and randomly changed. Therefore, it is difficult to design a single antenna to meet various harsh reception environments and conditions. It is required that the fading characteristics of the signal are unavoidable; therefore, the RF engineer uses diversity technology to design a multi-antenna receiving system from a system perspective, that is, each antenna receives the fading signal relatively independently, and the central processor performs specific processing on these signals, thereby Reduce the impact of fading on the entire receiving system and ensure the consistency of the overall system receiving quality in the fading environment.
As the in-vehicle infotainment function increases, the receiving system also tends to be more complex, which means that the development of the system will require more comprehensive analysis and coordination.
Autopilot mode is the long-term goal of smart cars
Driving safety has always been a top concern for automakers, and government agencies involved in transportation have developed a series of regulations to coordinate the daily traffic accidents and the technical hazards of any registered vehicles.
A large number of statistics show that most traffic accidents and casualties are caused by human error. Therefore, in order to effectively reduce the accident rate, auto manufacturers have developed various auxiliary driving devices, such as car navigation, adaptive cruise control, pedestrian protection. Hit protection warnings, car communication, etc.
From another perspective, most traffic accidents are caused by the collision of at least two vehicles. Imagine that the two vehicles causing the accident are equipped with devices that use a certain technology. This technology allows the two vehicles to communicate with each other, and to make mutual avoidance or braking actions in time before a collision may occur. The car will no longer come together.
The above technology is one of the in-vehicle communication, namely inter-vehicle communication (V2V, C2C), which is based on IEEE 802.11p technology and is very similar to the WiFi technology used in daily applications; it is conceivable that once all vehicles use this technology, The car-to-vehicle interconnection can be realized, and the collision probability between the vehicles can be greatly reduced, thereby realizing safe driving and driving safety.
A further technology is the Vehicle-to-X (Car-to-X), the vehicle networking technology (IOV), which is the vehicle-to-vehicle, vehicle, and various devices involved in the use of roads. An intelligent, interactive transportation integrated management control system (ITS); the realization of this technology will mean that human dream driving automation becomes a reality.
From the perspective of an RF engineer, one of the key parameters in the system is the fading characteristics in the communication link. As mentioned above, the design of the receiving system in motion is very complicated, and comprehensive and thorough analysis and coordination is the best way to ensure the quality of the system.
in conclusion
With the increasingly strong market demand for telematics systems, governments have made corresponding policies and plans. Major auto manufacturers and related accessory manufacturing companies are actively stepping up the development and production of complementary products. The engineer's perspective explores the relevant technology applications in this global driving safety issue.
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Product introduce:
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