"Telephone" Electromagnetic Wave PPT Courseware 2

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"Telephone" Electromagnetic Wave PPT Courseware 2

conveying information in ancient times

Flying Pigeon Passing Letters

Post stations set up by the government and letters delivered by the private sector

Convey messages with special sounds, such as bells, drums, firecrackers, etc.

Use lights, firelights, such as Kongming lanterns, beacons, etc. to convey information

modern delivery of information

Wired communications: telephone, telegraph, television

Wireless communications: radios, walkie-talkies

Digital communications: Internet, digital TV

Paper communication: letters, newspapers

1. Electric current transmits information to distant places

1. basic structure of telephone

2. How the phone works

3. Electric current carries information to distant places

2. The role of telephone exchange

Think about it and draw a picture

(1) How many phone lines are needed?

(2) How can we reduce the number of telephone lines?

3. Analog communication and digital communication

1. Analog and digital signals

Telephone signals are divided into two types: analog signals and digital signals.

(1) Analog signal

Take a telephone signal as an example: when the microphone converts sound into signal current, the frequency and amplitude of the current change exactly the same as the frequency and amplitude of the sound.

(2)Digital signal

Take telegraph signals as an example: a combination of dots "·" and "—" is used to represent various numbers, and a certain combination of numbers represents a Chinese character.

The length of sound and light, the presence or absence of voltage and current, the numbers 0 and 1, the N and S poles of the magnet, and other different symbolic information can all form a digital signal.

2. Transmission of analog and digital signals

(1) Analog signal communication can only be used to transmit voice signals (1G signals)

(2) In addition to transmitting voice signals, digital signal communication can also transmit text and pictures (2G signals)

(3) Compare the advantages and disadvantages of the two signal transmissions

Disadvantages of analog communication:

susceptible to interference

amplification distortion

create noise

Advantages of digital communication:

Small signal distortion

Easy to store

Easy processing of transmitted data

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For more information about the "Electromagnetic Wave Telephone" PPT courseware, please click the "Electromagnetic Wave ppt Telephone ppt" tab.

30 PPT materials of white three-dimensional little people holding phones and making calls:

These are 30 PPT materials of white three-dimensional little people holding a phone and making calls. .PPTX format;..

"Telegraph and Telephone" Information Transmission PPT Courseware 2:

"Telegraph and Telephone" Information Transmission PPT Courseware 2 How to quickly transmit long-distance information? After three years of study by the American painter Morse, the first telegraph machine came out in 1837. Morse successfully replaced human civilization with the on, off and long interruption of electric current.

"Telegraph and Telephone" Information Transmission PPT Courseware:

"Telegraph and Telephone" Information Transmission PPT Courseware What is a telegraph? After three years of study by the American painter Morse, the first telegraph machine came out in 1837. Morse successfully used the on, off and long breaks of electric current to replace human words for transmission. This is Ding Ding..

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Update Time: 2024-10-19

This template belongs to Physics courseware Lu Jiao Edition Ninth Grade Physics Volume 2 industry PPT template

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