Telecom Common Knowledge 300 Questions

Author: You Wuyang et al.
Publisher:
Publishing Date: 2002-06-01
Features: From the intermittent notes played by a Teledeltta telegraph to the grand symphony of the Internet by the end of the 20th century, telecommunications has undergone over a century of development, growing from nothing to something, from small to large, and ultimately becoming a leading industry driving economic development and social progress. Today, more and more people are exploring the wonderful world of information on the Internet, sending New Year's blessings to their loved ones overseas through radio waves. All of this demonstrates that people have realized that modern telecommunications has become an integral part of their lives. Phrases like "call me on my mobile," "Are you online?" and "send me a text message" have become popular expressions. The concept that "time is money" and "information is wealth" is deeply ingrained in people's minds. Just like food, clothing, shelter, and daily necessities, telecommunications consumption has become an important part of the work and lives of the Chinese people. In 1892, when 2,000 Ericsson telephones were shipped from Sweden to Shanghai, the Chinese people mistakenly called these hand-cranked foreign gadgets "coffee grinders." At one time, telephones were luxury items for the wealthy, symbols of status, position, and privilege. Over a decade ago, "brick-like" mobile phones entered the Chinese market, costing tens of thousands of yuan and keeping ordinary people at a distance. At that time, mobile phones became tools for the newly affluent to flaunt their wealth. "The swallows of the former nobles and officials have flown into the ordinary homes of the people." Today, telephones are no longer rare, just like color TVs and refrigerators, have become daily necessities for ordinary people, and "multiple phones per household" are increasingly common in cities. Pagers and mobile phones have also "lowered their stance," not only becoming more affordable but also smaller and more exquisite. Mobile internet access has become trendy, and the internet has been put into pockets. From foreign-invested enterprises to migrant workers moving to cities, from businesspeople traveling between cities to tourists immersed in famous mountains and rivers, from lamas on the plateau to fishermen casting nets in the South China Sea, from border guards stationed in the northern regions to scientific researchers exploring Antarctica, all can enjoy the convenience brought by modern communication. The dawn of the information age has arrived, and people have never valued information communication and emotional exchange as much as they do now. All of this is based on the rapid development of China's telecommunications industry and informatization. In the past decade, the scale of China's telecommunications network and the number of users have grown at a high speed. By the end of 2001, China had the world's largest mobile communication network, wireless paging network, and fixed telephone network. In the past two years, new telecommunications technologies and services have emerged one after another, and new telecommunications terms have appeared endlessly, such as "CDMA," "WAP phones," "Bluetooth technology," "broadband," "mobile internet," and "3G." All of these are gradually influencing and changing people's lives. This book adopts a Q&A format, using simple and easy-to-understand language and lively, vivid text to briefly introduce the basic concepts of telecommunications commonly encountered in daily life, the basic working principles of systems, and the development of new technologies and services. The book also reviews the history of telecommunications, introducing the origins and development of telecommunications technology, as well as the fascinating anecdotes. The content of this book is rich, the material is fresh, and the writing is clear, making it an invaluable popular science book to help people gain knowledge of telecommunications. It can also serve as an entry guide for those who wish to enter the telecommunications field.
If the number is local, the exchange checks whether the called user is available. If not, the exchange sends a busy signal to the calling user. If the called user is available, the exchange searches for an idle path from the exchange to the called user, sends a signal to the called user to indicate that a call has come in, and also sends a ringing signal to the calling user to indicate that the call is being made to the called user. Once the called user picks up the phone, the signal is immediately recognized by the exchange, and the signal to both parties is stopped, establishing the communication path between the two, allowing them to talk.
If the number is long-distance, the exchange immediately sends the received number to the long-distance transmission center for analysis, sends the number to the exchange of the corresponding region, and the exchange of that region analyzes and searches for a path, then connects the two users.
How does a magnetic card phone work? A magnetic card phone is a high-tech product that combines computer technology and telephone technology, using a magnetic card to control calls and pay for them. The phone card is portable and combines the functions of making calls and charging, allowing the phone to make local, domestic, or international direct-dial calls, automatically settle accounts, and provide all-day service. The system of a magnetic card phone consists of the following three parts:
① Phone card: It is made of special magnetic materials and polyester film, with the size of a business card. The card has 2 or 3 magnetic tracks for recording information. When the user inserts the card into the card slot of the magnetic card phone according to the arrow direction marked on the card, the screen immediately displays the amount of money on the card and prompts the dial tone, allowing the user to make a call. The call time of a magnetic card phone is calculated from the moment the other party answers, with a charge per minute. As long as one party hangs up during the call, the magnetic card phone will store the remaining amount on the card and display the balance on the screen, and the card will automatically eject. Some magnetic card phones also punch holes in the card to indicate the remaining balance on the card. During the call, if the remaining amount on the card is not enough to pay for one minute of the call, the phone will automatically issue a warning sound. The user can press the "change card key," and the old card will automatically eject, and a new magnetic card can be inserted to continue the call. If the warning sound appears for 15 seconds and the user does not insert a new card, the phone circuit will be disconnected.
② Magnetic card phone: It consists of a transmitter and receiver, a magnetic card unit, a printed circuit board, power equipment, and a sturdy outer shell. The magnetic card unit consists of a mechanical part and corresponding circuits. Under the control of a microprocessor, it completes functions such as card transmission and ejection. After the card is inserted into the card slot of the phone, it is transmitted to the magnetic recording and regeneration system, where the head reads and writes data; after the call is finished, the card is ejected. The printed circuit board includes a control circuit board, a conversation board, and a display board.
⑧ Remote alarm center of the magnetic card phone: The remote alarm center is located in the telephone bureau and can perform simple remote operations. For example, it can issue instructions to the phone to report the results of automatic diagnosis and the usage status of the phone. Of course, it can also activate manual alarms based on the operating status or action status of the phone. When the remote alarm