As an important technology that affects our lives, how much do you know about radio?

When it comes to radio, many people may think that it is a very old concept, but in fact, radio plays a very important role in our lives. Currently, radio has become the most widely used medium for the masses. According to the Ministry of Industry and Information Technology, 95% of the world’s population can receive radio signals. In our life, radio is everywhere, the use of cell phones, Wi-Fi connection, invisible and invisible radio brings a lot of convenience to people’s daily life. However, due to the complexity of radio technology, the public still does not know much about radio, so let’s walk into the world of radio today.

CKWX Radio History

The Road to the Birth of Radio

The theory of radio is based on the electromagnetic field theory of British physicist Maxwell. The German physicist Hertz first discovered the existence of electromagnetic waves through experiments in 1887. All objects in the world emit electromagnetic waves, for example, light is the electromagnetic waves emitted by the sun. Although this electromagnetic wave is not observed by the human eye, snakes possess this ability and rely on their keen and unique perception to catch their prey at night. These electromagnetic waves propagating in free space are what physics refers to as radio, which exists not only in the air but also in the vacuum, and the technology by which people transmit signals through radio waves is radio technology.

The Italian inventor Marconi is known as the “father of radio communication” because he was inspired by Hertz’s experiments and began to experiment with radio transmission and obtained a transmission distance of a few meters in 1894. The real landmark came on December 12, 1901, when, after many trials and long explorations, Marconi completed the first radio communication across the Atlantic Ocean and was able to receive telecommunications from the United Kingdom in the United States. This news was a great shock to people at that time. In the history of mankind, the desire to transmit messages quickly has always been a constant wish and a difficult problem. Since Marconi’s invention, human communication has entered a new era, no longer having to rely on the delivery of animals and letters, radio has since allowed messages to be sent around the world at any time.

Soon, the wireless telegraph invented by Marconi was widely used around the world. In reality, the earliest application of radio technology was in navigation, when people used Morse telegraph to transmit information between ships and land. Marconi-style radio stations were set up on the coasts and forts of many countries. But it still had many shortcomings. First, the Marconi transmitter’s oscillating circuit and antenna are combined, which makes the transmitter’s power very low; second, the wireless communication used by Marconi is not able to be tuned, which makes its radio waves emitted from each other very easy to interfere; more annoying is the lack of reliable telegraph receiving device in the Marconi wireless telegraph system.

Invention of radio - Wikipedia

To address the drawbacks of Marconi’s telegraph facilities, German physicist Karl Ferdinand Braun made improvements. He invented a new tuning technique based on the tuned powder detector of the British engineer Joseph Lodge from 1902, which enabled radio telegraphy to be transmitted and received in different frequency bands in a directional manner, reducing interference, and this technique was also the basis of radio. In 1909, the Nobel Prize jury awarded the Nobel Prize in Physics to Marconi and Braun for their contributions to the cause of human radio engineering.

The Beginnings of Radio Technology

When radio technology was in its infancy, the Morse code, which we often see in old movies, was a major “killing tool” that every radio communicator had to master. This is because the earliest radio telegraphs were very limited in the number of messages they could transmit, so people tried to use a kind of intermittent signal code to replace the messages, and the famous Morse code was born. In Morse code, there are two signals, the short “・” and the delayed “-“, and people can use different combinations of signals to express different meanings, such as “—” for the letter a and “—” for the letter d. In this way, with the In this way, with the support of Morse code, simple symbols can also convey a content and interesting text. With the development of technology, Morse code has disappeared from everyday life. However, many radio enthusiasts and military broadcasters still use it because it can work under very harsh communication conditions and has a high message density.

A Basic Look At How Radio Technology Really Works

In 1920, the world’s first official broadcast began in the United States, and radio broadcasting has since flourished in many other countries.

How radio technology works

There is a typical analogy that describes the process: When you throw a stone at a calm lake, the water waves will travel a long way. If these water waves can record information, then as the ripples dissipate, the information can also be transmitted to faraway places. Radio waves can travel in free space (e.g., air and vacuum), so as long as humans load information on radio waves of a specific frequency, then the purpose of transmitting information can be achieved. Specifically, this technology works by generating radio waves when the strength of the electric current in the conductor changes. By the phenomenon of radio waves generated by the change in the strength of the current in the conductor, the information can be loaded on the radio waves after modulation. When the radio waves transmitted through space reach the receiving end, the electromagnetic field change caused by the radio waves generates current in the conductor, and the information is extracted from the current change by demodulation to realize the information transmission.

Wireless telegraphy - Wikipedia

The road of development of radio technology

Although at the beginning, radio waves could only transmit some simple “drops”, but with the continuous development of technology, people’s research on radio gradually deepened, radio is widely used in many fields such as communication, navigation, radar, heating, power, remote control, astronomy, etc.. Among them, the application of radio in the field of communication is the most familiar, broadcasting, telephone, television, emergency services (positioning), data transmission and other applications in people’s lives have become very common. With the continuous development of computer technology and information technology, various wireless networks based on wireless transmission technology are becoming an important part of people’s lives.

The history of the development of radio is, to a large extent, the history of people’s research and application of each waveband. The development and application of radio has gone through two stages: software radio and cognitive radio. Software-defined radio is a radio broadcasting communication technology, which was formally proposed by scientists in the early 1990s. One of its main features is that it is based on software-defined radio communication protocols rather than being implemented through hardwired connections. Band, air interface protocols and features can be upgraded through software downloads and updates without a complete hardware replacement.

When Was Radio Invented? How Radio Changed The World

After decades of promotion and worldwide research, the concept of software radio has not only been widely recognized, but also widely applied. 3G, 4G, multi-band multi-mode radio, and joint tactical radio systems are all designed and developed with the concept of software radio, and even GPS, which accomplishes a single function, is designed with software to meet the development needs of navigation technology.

Awareness radio is a wireless communication technology that includes an intelligent transceiver. It was proposed by scientists in the early 21st century to improve the utilization of the free spectrum. The intelligent transceiver in cognitive radio detects which bands are unoccupied and which bands are in use, and when certain bands are detected to be free, the CR system can temporarily use the band for communication. Cognitive radio can sense the surrounding electromagnetic environment, communicate intelligently with the communication network through Radio Knowledge Description Language (RKRL), and adjust the transmission parameters (communication frequency, transmit power, modulation method, coding system, etc.) in real time, so that the radio parameters of the communication system can not only adapt to the rules but also match the environment to achieve high reliability of the communication system at any time and any place. This is to achieve high reliability and efficient use of spectrum wherever and whenever possible.

Compared with software radio and cognitive radio, the former is concerned with the software approach to radio system signal processing, while the latter emphasizes the ability of the wireless system to sense changes in the propagation environment and adjust the system parameters accordingly to achieve optimal adaptation. In this sense, cognitive radio is a higher-level concept that includes not only signal processing but also the high-level activities of reasoning and planning based on corresponding tasks, policies, rules, and goals.

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Realization of Radio Communication

Over the past 100 years, communication technology has developed rapidly, and the application of telegraph, telephone, radio, television and other communication technologies has greatly accelerated the pace of modern life, making the ancient dream of “smooth ears” and “clairvoyance” a reality.

To carry out radio communication, you need to send and receive radio waves. Antenna is the necessary equipment for transmitting and receiving radio waves, we can often see a variety of antennas. To carry out radio communication, the first thing to do is to transmit radio waves. Radio wave transmitters have an important part called the oscillator, which generates a high frequency alternating current, high-frequency alternating current flow through the antenna, generating a high frequency electromagnetic field in space. As this electromagnetic field is doing periodic changes in the surrounding area and produce a new electromagnetic field …… so that the electromagnetic wave is emitted.

Radio Technology - EnOcean

Radio broadcasting transmits sound, while television broadcasting transmits not only sound, but also images. The oscillator generates a high-frequency alternating current that is used to carry information such as sound and images, called a carrier wave. By adding information to the carrier wave and transmitting it, the information can be transmitted to distant places. Adding information to the carrier wave is to make the carrier wave change with the signal, this technique is called modulation. There are two ways of modulation, a common one is to make the amplitude of the high frequency carrier wave change with the signal, this way is called amplitude modulation (AM). Amplitude modulation is used for radio broadcasts in the medium-wave and short-wave bands. In the microwave band, the image signal of a TV broadcast is also amplitude modulated. Another modulation method is to make the frequency of the high-frequency carrier wave change with the signal, and this modulation method is called FM.

The amplitude of FM remains unchanged, the ability to resist interference is stronger, and the distortion during transmission is smaller. However, the structure of FM receivers is more complex than AM receivers, and the service radius is smaller. Many of the radio stations we are familiar with are FM radio stations, which can broadcast high quality music and language programs.

There are many radio and television stations in the world that transmit electromagnetic waves every minute of every day. Therefore, there are many electromagnetic waves around us. When you receive radio broadcasts, you must first select what you need from the many radio waves. When we turn the radio knob to select a station, we are actually selecting the electromagnetic wave we need, which is technically called tuning. After tuning, the receiver gets a high-frequency current with a message marker. This high-frequency signal current is not yet the desired signal itself. To get the required sound and image information, they must be “taken” out of the high-frequency signal current, a process called demodulation. The signal obtained through demodulation has to be amplified. If the information transmitted is sound, you can make the speaker sound; if the information transmitted is image information, you can make the picture tube display images.

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Application of radio technology

In today’s life, we can’t live without radio, and the applications of radio are becoming more and more diverse, including not only wireless data networks, but also various types of mobile communications and radio broadcasting.

The earliest application of radio is in the field of communication, where people can transmit information over long distances for the first time with the help of radio. When radio technology was introduced, it was quickly applied in the field of navigation, where military ships would use it to send and receive orders and notifications, and civilian ships would use it to call for help or to transmit other information. Mobile phone is the most popular wireless communication device, and people can talk freely as long as they are in the signal coverage area. In addition, technologies such as wireless LAN and Bluetooth use radio technology to transmit data over short distances.

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Radio navigation can guide people to their destinations smoothly. In this technology, the satellite can use radio waves to determine the navigation parameters of the carrier (such as bearing and speed) and calculate the deviation from the predetermined route so that it can be corrected in time to maintain the correct route. If this process is continued, the radio can be used for continuous positioning and eventually radio navigation. Radio navigation is not limited by time and weather, and is highly accurate, fast and easy to operate. Modern wireless communication technology is more developed, and space communication technology is becoming more mature. Mobile communication has become essential in our daily life. Mobile communication has gone through 1G (analog), 2G (digital), 3G (high-speed) era, and has now entered the 5G period. Since the 3G era, mobile communication has really brought people into the era of multimedia mobile communication, web pages, music, pictures, video, etc. can be realized on smart phones for a good customer experience.

Wireless local area networks are widely used in healthcare, enterprise network coverage, warehouse management, restaurant retail, video surveillance, etc. The WiFi hotspot network logo can be seen everywhere in daily life. In fact, WiFi is a trademark of the WLANA (Wireless Local Area Network Alliance), one of the technical standards for WLANs.

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In the era of rapid development of information technology, the Internet of Things (IoT) is gaining momentum, a network that connects all objects through the network. Obviously, this scenario is unimaginable if we connect through wired network. The Internet of Things is widely used in many fields such as intelligent transportation, environmental protection, government work, public safety, safe home, intelligent firefighting, industrial monitoring, environmental monitoring, elderly care, personal health, flower cultivation, water system monitoring, food traceability, enemy detection and intelligence gathering, etc. The application prospect is very broad.

Radio Technology in Today’s World

Radio technology is also very present in real life. Radio is needed for the transmission of sound, such as radio telegraphy, AM radio, FM radio, and voice radio used in navigation and aviation. Radio technology is also needed for telephony, television, emergency services, data transmission, Bluetooth, navigation, radar, heating, power, astronomy, and other fields.

Some people sum up radio in this way, saying that it is the “overpass” for people to realize free communication. With the rapid development of radio communication technology, cell phones not only meet people’s needs for free communication anywhere, but also become a personal smart mobile terminal that combines communication, photography, entertainment, financial management, shopping and other functions. As early as 2013, there are data showing that the number of cell phone users in China exceeded 1.1 billion, ranking first in the world. The pagers that were popular across the country, the walkie-talkies used for dispatching and commanding, the Bluetooth used for short-range wireless communication, the Wi-Fi used for wireless local area networks and satellite phones, and so on are all inseparable from the radio. Public mobile communication has evolved through five generations. From the need to make phone calls while on the move to the high-speed download capability of mobile communications (5G), radio has played an important role. Radio is also the “seven rainbows” that enrich people’s cultural life. Radio and television rely on radio waves to bring news from around the world to us every day, thousands of miles away. After decades of development, China’s radio and television network has become the world’s largest radio broadcasting network, and statistics from 2013 show that more than half of the country’s households watch television through the wireless network, with more than 15,000 television relay stations and more than 30,000 television transmitters. It can be said that our convenient life today is built on the application of radio technology.

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Focus on Radio Safety

For a long time, the safety of radio has been a matter of concern. Take cognitive radio for example, it faces five major security threats. First, information theft. Since the information transmission medium of radio communication is open space, this greatly reduces the difficulty of illegally intercepting communication signals. And because the interception of signals is a passive behavior, it increases the difficulty of detecting the problem through signal detection methods. Second, malicious interference. The radio receiving antenna is located in the open space, in the reception of useful signals at the same time, but also by the existence of a variety of useless information in the space of interference. For example, some malicious attackers can arbitrarily insert the receiver’s transmission channel to reduce the receiver’s input signal-to-noise ratio, affecting the effectiveness of the communication. In addition, some malicious attackers can make the receiver get wrong information by imitating useful signals. Third, the interference of cognitive users to authorized users. Due to the hidden terminal effect and other environmental factors, the perception of the cognitive user to the primary user is inaccurate and untimely, and the authorized user may be interfered. The unfair phenomenon among users. Fourth, imitation of authorized user attacks. Under the situation of spectrum resources shortage, the limited spectrum is occupied for oneself, and in some malicious attacks, the availability of spectrum resources will be destroyed. Fifth, denial-of-service attacks. In cognitive radio networks, the common control channel is the physical basis for transmitting spectrum-aware information between nodes. By sending a large amount of useless control information, the attacker saturates the control channel and makes the control channel unavailable to other cognitive users. At the same time, cognitive radio faces a number of other security threats. For example, attackers can exploit the security vulnerabilities of various protocols in the application layer to degrade the service quality of cognitive radio through viruses, Trojan horses and other malicious programs.

v radio frequency hazard - SafetyKore

In the face of these security threats, spread spectrum communication technology is an effective way to solve the problem of information theft and interference. The main idea of frequency expansion communication includes direct expansion, frequency hopping, etc. The main idea is to enhance the concealment and interference resistance of the signal by expanding the bandwidth of the communication signal. In addition, a more stringent authentication mechanism can be used to prevent the leakage of information and data. A suitable cryptographic algorithm can make the communication signal unable to provide the information of interest to the eavesdropper even if it is intercepted. Better identification of authorized user signals is a fundamental way to defend against imitation authorized user attacks. To this end, it is possible to perform multidimensional discrimination using physical features other than the signal itself.

In order to raise awareness of the importance of radio and its role as a communication vehicle for educational development, information dissemination, and the dissemination of critical information in natural disasters, UNESCO decided to designate February 13 as World Radio Day on November 3, 2011. While we enjoy the convenience of radio technology, we must also take its safety into account. Various radio services “go their own way” on different frequencies. Radio management agencies ensure the safety and orderliness of radio waves through scientific planning and management of these “roads” to ensure the normal operation of various radio services. Of course, creating a harmonious, green and safe electromagnetic environment also requires the concerted efforts of the whole society.