Landline phones, also referred to as fixed phones, usually refer to phones that are fixed in a certain location and do not move. Contrary to mobile phones, they are mostly used in corporate units. Landline is one of the important means of communication in modern times. The microphone in the phone is used to modulate the current and voltage on the telephone line through the vibration of sound. That is, the sound is converted into a voltage signal and transmitted to the other end of the phone through the telephone line, and then used to send the call. The converter converts the voltage signal into a sound signal. Because it is usually fixed in one location, the academic name is a landline phone, which is also commonly known as a landline phone. There are several types of this kind of telephone, such as: fax telephone, mother-child telephone, etc.
Technological Development
In the decades after the invention of the telephone, issues surrounding the operation and technology of the telephone have , a large number of patents were applied for, Strowger's "automatic dialing system" reduced various problems caused by manual wiring, the application of dry batteries reduced the size of the phone, and the application of loaded coils reduced signal loss in long-distance transmission. In 1906, Lee De invented the electronic test tube, and its loudspeaker function led the direction of telephone service. Later, Bell Telephone Laboratories made an electronic triode based on this. This research was of great significance. On January 25, 1915, the first interborough telephone line opened between New York and San Francisco. It used 2,500 tons of copper wire, 130,000 poles and countless loaded coils, and three vacuum tube amplifiers along the way to strengthen the signal. On July 1, 1948, scientists at Bell Labs invented the transistor. This is not only of great significance to the development of telephones, but also has a huge impact on all aspects of human life. In the following decades, a large number of new technologies emerged, such as the production of integrated circuits and the application of optical fibers, which all played a very important role in the development of communication systems.
China's Development
After the Opium War, while Western powers plundered land and wealth in China, they also brought modern postal and telecommunications to China. In 1900, my country's first local telephone was launched in Nanjing; from 1904 to 1905, Russia set up radio stations from Yantai to Niuzhuang. China's ancient postal system and private communication institutions were gradually replaced by advanced postal services and telecommunications.
During the Republic of China, China’s postal and telecommunications communications were still under the control of Western powers. Coupled with years of war, communication facilities are often damaged. During the Anti-Japanese War, the Japanese imperialists transformed and expanded the telecommunications network system out of war needs and the purpose of long-term domination of China. They took advantage of China's economic and technological backwardness and the corruption of the political system at that time to improve technology, equipment, maintenance, and management. and other aspects to control China’s communications industry.
Before 1949, China's telecommunications system developed slowly. By 1949, China's telephone penetration rate was only 0.05, and there were only 260,000 telephone users.
After 1949, the Central People's Government quickly restored and developed communications. The Beijing Telegraph Building built in 1958 became an important milestone in the history of communications development in New China. During the ten-year "Cultural Revolution", post and telecommunications suffered another blow. They have been losing money and business development has stagnated. By 1978, the national telephone penetration rate was only 0.38, less than 1/10 of the world level. China, which accounted for 1/5 of the world's population, had less than 1% of the world's total number of telephones. There were less than 10% of telephones per 200 people. One, 75 years behind the United States! The proportion of switch automation is low. Most counties and rural areas still use "shake handles". Long-distance transmission mainly relies on open wires and analog microwaves. Even in Beijing, 20 long-distance calls cannot be reached every day, and 15 It will take 1 hour to get through. People who made calls at the Telegraph Building had to wait in line with their lunch.
In 1978, the national telephone capacity was 3.59 million, the users were 2.14 million, and the penetration rate was 0.43.
After the reform and opening up, backward communication networks have become a bottleneck for economic development. Since the mid-1980s, the Chinese government has accelerated the construction of basic telecommunications facilities. By March 2003, the number of fixed phone users reached 225.626 million, and 221.491 million mobile phone users.
How many people have worked hard to deliver information faster and better in ancient and modern times. In the more than 100 years of telecommunications development, people have tried various communication methods: the original telegraph used something like " "Digital" means of expression to transmit information; later, telephones that transmitted information with analog signals appeared; with the advancement of technology, digital methods have once again received attention for their obvious superiority, digital program-controlled switches, digital mobile phones, optical fiber digital transmission... …The wheel of history is still moving forward.