"Radio, Television and Mobile Communications" Information Transmission PPT

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"Radio, Television and Mobile Communications" Information Transmission PPT

Part One Content: Basic Knowledge Key Points

Knowledge point 1: Transmission and reception of radio broadcast signals

1. In radio broadcasting, the microphone converts the announcer's voice signal into an electrical signal, and then uses a modulator to load the audio electrical signal onto a high-frequency current, and then generates electromagnetic waves through the antenna and transmits them into the air; the antenna of the radio receives various The electromagnetic wave uses the tuner of the radio to select a signal of a specific frequency. The electronic circuit in the radio takes the signal out, amplifies it, and sends it to the speaker.

2. Receiving antenna that receives electromagnetic waves (D)

A. Only receive high frequency signals

B. Only receive low-frequency signals

C. Only receive intermediate frequency signals

D. Can receive signals of various frequencies

3. The process of loading audio electrical signals onto high-frequency current is called (A)

A. Modulation B. Tuning

C.Detection D.Emission

Knowledge point 2: TV transmission and reception

4. Some pot-shaped antennas are commonly seen on the top of postal and telecommunications buildings. Regarding the function of such antennas, the following statement is correct (B)

A. This is a model for advertising

B. The concave surface of the antenna is tilted upward to receive satellite signals.

C. The concave surface of the antenna faces the horizontal direction and is used to receive satellite signals.

D. Satellite signals can be received no matter which direction the antenna faces

5. When viewers choose TV programs from different channels at home, they are actually changing (D)

A. The speed of electromagnetic waves emitted by TV stations

B. The speed of the electromagnetic waves received by the television

C. The frequency of electromagnetic waves emitted by TV stations

D. The frequency of electromagnetic waves received by the TV

Knowledge point 3 Mobile phone

7. Mobile phones are both transmitting and receiving stations. Mobile phones must rely on fixed base stations for conversion during calls.

8. Among the following statements about mobile phones, which one is wrong (B)

A. Mobile phones can both receive and emit electromagnetic waves.

B. The transmitting power of mobile phones is very large, and the sensitivity of their antennas is very high

C. Mobile phone calls to other users require base station transfer

D. Mobile phones use microwave signals to communicate with the telephone network

Radio, television and mobile communications PPT, part 2: improvement of comprehensive capabilities

9. Television uses electromagnetic waves to transmit image signals and sound signals; its propagation speed is approximately 3×105 km/s.

10. No matter where the phone is located, the information must first be transmitted to the base station in the area, then to the base station in the calling area, and finally to the other party's phone.

11. As shown in the picture, there are English markings next to the jacks on the back of some TVs and VCD players, where AUDIO IN refers to audio input, AUDIO OUT refers to audio output; VIDEO IN refers to video input, and VIDEO OUT refers to Video output.

12. The snowstorm in the south caused power outages in some areas, and people were unable to watch TV programs normally. In order to learn about the snow disaster, a classmate made a very simple radio based on what he learned about radios. However, when listening to the radio with this radio, the signals of many stations can always be heard at the same time, resulting in poor listening effect. The main reason for this phenomenon is that this radio lacks (D)

A. Antenna B. Detector C. Modulator D. Tuner

13. When using a radio to receive radio waves, what the radio’s receiving antenna receives is (D)

A.Current B.Image signal

C. Sound signal D. Electromagnetic wave carrying sound signal

14. The correct order for radio reception is (C)

A. Tuning → Demodulation → Receiving antenna → Speaker

B. Tuning→receiving antenna→demodulation→speaker

C. Receiving antenna → Tuning → Demodulation → Speaker

D. Receiving antenna → Demodulation → Tuning → Speaker

15. In the transmission and reception of television, the devices that convert sounds and images into electrical signals are (B)

A. Headphones and camera B. Microphone and camera

C. Microphone and picture tube D. Headphones and picture tube

16. The tall TV towers everywhere are landmark buildings, and the function of the antenna on the TV tower is (D)

A. Convert sound and image signals into electrical signals

B. Load sound and image signals onto high-frequency current

C. Load audio and video electrical signals onto high-frequency current

D. Let the high-frequency current carrying audio and video signals generate electromagnetic waves

17. TV signals include image signals and sound signals. During the transmission process of TV signals from the TV station transmitter to the TV set, which of the following statements is correct (A)

A. Sound signals and image signals are both loaded on electromagnetic waves.

B. Sound signals and image signals are both loaded on current

C. The image signal is loaded on the current, and the sound signal is loaded on the electromagnetic wave.

D. The sound signal is loaded on the current, and the image signal is loaded on the electromagnetic wave.

Radio, television and mobile communications PPT, Part 3: Expansion, exploration and breakthroughs

23. Everyone is very familiar with television, and it can be said that they cannot live without it every day. Different TV stations occupy different channels. Channels are actually pre-designed frequencies. Each channel has a fixed transmitting (receiving) frequency. In the past, black and white TVs only had 12 channels, but now they have developed to more than 90 pre-selected channels. New TVs can automatically search for channels so that each program has the best effect.

(1) The "pre-designed frequency" mentioned in the article refers to (C)

A. Audio frequency B. Video frequency C. Radio frequency

(2) Why do different TV stations use different frequencies?

(3) What is the process of automatic TV channel search in physical terms?

(2) In this way, the signals of different channels will not be mixed together. The frequency of each channel of each TV station is different. When you want to watch a certain channel, you only need to receive the signal of the corresponding frequency; if the frequencies of different TV stations are the same , the signals are mixed together, and the program cannot be received and displayed normally.

(3) is a tuning process.

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Update Time: 2024-11-16

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