What is Telephony?

Telephone English: Telephone, from the Greek (tle (meaning "far") and (phn (meaning "voice"), the old translation of the German style) is a remote communication device that can transmit and receive sound. As early as the eighteenth century, the term "telephone" was used in Europe to refer to a microphone (stringed to a cup) with a string. The appearance of the telephone is attributed to Alexander Graham Bell. The principle of early telephones was that the speaking sound is a composite vibration in the air, which can be transmitted to a solid body and transmitted through conductive pulses on conductive metals. Bell filed a patent for the phone in March 1876.

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Phone English:

Telephone

Phone communication is through

The telephone was invented by the American AG Bell in 1876. He uses two wires to connect two microphones and receivers with the same structure and a vibrating diaphragm on the electromagnet. First, two ends of the call are realized. But the communication distance is short and the efficiency is low. The appearance of charcoal microphones in 1878 greatly improved the efficiency of telephone microphones. The receiver structure has also been improved. The earliest telephones were magnet telephones, which were powered by their own batteries and used hand generators to send call signals. In 1880, the common electric telephone set was replaced by the common electric switch to provide centralized power supply, eliminating the need for hand-broadcast generators and dry batteries. In 1891, a rotary dial-type automatic telephone appeared. It could send DC dial pulses, control the operation of automatic switches, select the called user, and complete the switching function automatically. Pushing telephone communications to a new stage. By the end of the 1960s, all-button electronic telephones appeared. In addition to the pulse numbering method, a dual-tone multi-frequency (DTMF) numbering method has appeared. With the development of program-controlled switches, dual-tone key telephones have gradually become popular. Electronic telephone circuits are moving towards integration, and telephone application specific integrated circuits have been widely used in various components of telephone circuits. Various multi-functional telephones and special-purpose telephones also came into being. By the early 1990s, there were telephones that integrated dialing, calling, and ringing functions on a single integrated circuit. With the development of voice recognition technology, new types of telephones that "dial directly" with voice are also emerging.

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The development of high-tech telephones has been formed with the development of wireless communications. The development trend of telephones has developed into IMT-200 services that can use satellite communications after Digital telephones and PCS. IMT-200 supports high-speed transmission of information, multimedia services such as packets, portraits, etc. In the future, all voice telephones can be used in various parts of the world. Telegraph users have direct access to circuits, paging, and e-mail. Internet telephony is an unstoppable development trend. The existing fixed telephones can no longer provide people's needs. In the future, fixed-line telephones are equipped with cameras and color LCD monitors. When we receive fixed-line telephones, we can see both sides.