Communication principle between fixed telephone and mobile telephone

1, the number signal dialed by the mobile phone user is converted into a unified format signal, and then transmitted by radio waves.

2. When the nearby base station receives the signal, after some processing, it will recover the signal and connect the other party's phone through other communication equipment of the base station.

3. If the other party is a fixed telephone, the signal should be connected to the wired telephone network through the local long-distance telephone program-controlled exchange.

4. If the other party is also a mobile phone, the base station will forward the received signal to other base stations, and all base stations will forward your signal once. As long as the other party is within the radio wave coverage of the base station, the two parties can talk.

5. The principle of dialing is understood from two aspects:

(1) the first is to dial.

At present, the dialing method of D T M F (dual tone multi-frequency (early pulse dialing) is basically adopted. Dual-tone multi-frequency refers to DTMF (dual-tone multi-frequency), and the DTM MF signal consists of eight frequencies. These eight frequencies are divided into two groups: low frequency group and high frequency group. When the "calling party" sends the DTMF signal dialed off-hook to the program-controlled exchange of this bureau through the telephone line. Through program-controlled exchange, it is transmitted from telephone line to telephone, realizing the conversation between the two parties.

② Second Call Principle

Conversation is a kind of communication technology that uses electricity as the medium and transmits language through the mutual conversion of acoustic energy and electric energy. When the "calling party" picks up the phone and speaks into the microphone, the vibration of the vocal cords excites the air to vibrate, forming sound waves. Sound waves act on the microphone to generate current, which is called speech current. The voice current is transmitted to the program-controlled exchange along the line, and the program-controlled exchange transmits the voice signal to the receiver of the "called party" phone, which plays the opposite role to the microphone-converting the current into sound waves and transmitting them to people's ears through the air. The simplest call process is completed.

In short, the easiest way for two users to talk is to connect two phones with a pair of wires. Telephone lines, cables, optical fibers and optical terminals are all transmission equipment of program-controlled switches.