What are the types of TV signal reception?

What I know is that wireless is to install a TV antenna on the roof of the building, and there is a well-known pot lid receiver that is like a pot, and the receiver is still installed on the roof of the building, and the signal is strong, and there are many channels, and there are set-top boxes, and there are thousands of light 、!!. If your problem is solved, thank you.

There are two types of general TV signals: digital signals and analog signals. Digital Signal Features:

1) Strong anti-interference ability and no noise accumulation. In analog communication, in order to improve the signal-to-noise ratio, it is necessary to amplify the attenuated transmission signal in time during signal transmission, and the noise that is inevitably superimposed on the signal during transmission is also amplified at the same time. As the transmission distance increases, the noise accumulates more and more, resulting in a serious deterioration of the transmission quality.

For digital communication, because the amplitude of the digital signal is a finite number of discrete values (usually two amplitudes are taken), although it is also interfered by noise during the transmission process, when the signal-to-noise ratio deteriorates to a certain extent, the method of judgment regeneration is adopted at an appropriate distance, and then the same digital signal as the original transmitter is generated without noise interference, so long-distance high-quality transmission can be realized. (2) It is convenient for encryption processing. The security and confidentiality of information transmission are becoming more and more important, and the encryption of digital communication is much easier than that of analog communication.

3) Easy to store, handle and exchange. The signal form of digital communication is consistent with the signal used by the computer, which is binary, so it is convenient to network with the computer, and it is also convenient to store, process and exchange the digital signal with the computer, which can make the management and maintenance of the communication network automated and intelligent. (4) The equipment is easy to integrate and miniaturize.

Digital communication uses time-division multiplexing, which does not require a bulky filter. Most of the circuitry in the device is digital and can be implemented with large-scale and ultra-large-scale integrated circuits, so it is small in size and low in power consumption. (5) It is convenient to form an integrated digital network and an integrated service digital network.

Using the digital transmission mode, the digital exchange can be carried out through the program-controlled digital switching equipment to realize the synthesis of transmission and exchange. In addition, the first business and various non-telephone services can be digitized to form an integrated service digital network. (6) The frequency band of the occupied channel is wide.

The frequency band of one analog ** is 4kHz bandwidth, and one digital ** accounts for about 64kHz, which is the main reason why analog communication is still viable. With the extensive use of broadband channels (optical cables, digital microwaves) (a pair of optical cables can open thousands of channels**) and the development of digital signal processing technology (the digital rate of a digital ** can be compressed from 64kb s to 32kb s or even lower), the bandwidth problem of digital ** is no longer a major problem. Analog Signal Features:

Analog signals are distributed in all corners of nature, such as daily temperature changes, while digital signals are artificially abstracted signals that are discontinuous in time. The electrical analog signal mainly refers to the electrical signal with continuous amplitude and phase, and this signal can be used by the analog circuit for various operations, such as amplification, addition, multiplication, etc. Analog signal refers to information expressed by continuously changing physical quantities, and the amplitude, frequency, or phase of the signal changes continuously over time, such as the sound signal currently being broadcast, or the image signal.

Digital and analogue.

The TV signal reception methods are:

1.Cable TV: It is the kind that is transmitted by optical cables, and it needs to pay the maintenance fee for viewing, which can be installed or not, depending on your ideas.

2.Wireless digital TV: It is a digital TV that relies on wireless reception, which is received at close range, and can receive clear wireless digital TV in the county seat and Qimaiwei, and should not be used in far away areas.

3.Analog TV Signals: Analog TV Signals, State Administration of Radio, Film and Television.

The regulation delay was shut down on March 31, 2021, and there was no thought of this signal.

4.Satellite television.

Satellite TV signals can be used, and you need to buy a satellite pot set-top box Tianzizi line to watch, and the cost is about a few hundred yuan.

5.IPTV.

Wireless reception, wired reception.

According to the different network structures formed in the process of cable television system, the following four forms are mainly introduced.

a) Traditional cable TV system.

The traditional wired battery system is mainly composed of four parts: signal source, front-end equipment, trunk transmission system, and user distribution network.

2) Two-way cable television system.

Two-way cable TV can not only transmit the TV signal provided by the front-end to the user, but also transmit the user's information back to the front-end or other users.

c) Digital cable television system.

Digital TV Yubi can be divided into digital satellite TV, digital cable TV, digital terrestrial open circuit TV, digital cable TV system is a new battery system that adopts digital processing in program settings, programs, transmission, storage, reception and display.

4) Integrated cable television system.

There are 10 types of cable TV interfaces, including R signal interface, composite signal interface, audio signal interface, YC signal interface, Y, P, PK signal interface, R, G, B signal interface, CKsu (VGA) signal interface, and digital signal interface.

Extension: Cable Television (CATV), also known as Cable Television (CATV), is developed from wireless television and first appeared in Pennsylvania, USA in 1950. Cable TV still retains the broadcast standard and signal modulation mode of wireless TV, and does not change the basic performance of the TV system.

Cable TV sends the recorded program to the user through a cable (cable or optical cable), and then uses the TV to replay it without radiating electromagnetic waves into the air, so it is also called closed-circuit television. Cable TV is a type of pay-TV that is paid for by the viewer rather than the funder.

Cable television (CATV) was originally referred to as "public antenna television", and now refers to all hybrid systems of ruined cable or fiber optic copper cables that are used to transmit ** signals to communities and residents' homes. The first cable television service appeared in 1948, when cable television networks were used to enable the simple retransmission of radio and television programs. In the early 80s of the 20th century, cable television networks achieved large-scale coverage around the world.

A cable television network enterprise refers to an operating enterprise that provides cable television services to subscribers.

Television systems first appeared in the United States in the 40s, and the original system was a shared antenna TV used in apartment buildings; Residents of apartment buildings are not likely to install antennas on their roofs, so shared antenna television systems have emerged. Shared antenna TV is simple, consisting of a shared antenna TV amplifier installed near the main antenna and a cable to each household.

Answer: Satellite television is a term for television that receives television signals transmitted by satellites. The satellite TV program signal is input to the high-frequency head through the ground antenna receiver for amplification and frequency conversion, and the C-band or Ku-band signal is converted into a signal with a frequency of 950 2150MHz.

The signal is fed into the tuner, where it is reamplified and reconverted. The output of 36MHz intermediate frequency signal, the signal through the QPSK (four-phase phase shift keying) demodulator to demodulate the I, Q analog baseband signal, I and Q analog baseband signal through analog-digital (AD) conversion, QPSK decoding, forward error correction (FEC) and other processing, the output byte number of 8 bits MPEG-2 data stream. The demultiplexer completes the MPEG-2 data unpacking, decomposes the sound, synchronizes the control and other data information.

MPEG-2 decoder completes the tone, decompression, decoding and other functions, restores the data information into a complete image and sound signal, and then transforms the audio D A through the encoder and audio D A to output the analog sound required by the TV.

Successful emission depends on the condition of the ionosphere, because the wave is particle-like, and the instability of the ionosphere will interfere with the transmission of the wave, which is generally stable.

The interaction between the electric field and the magnetic field produces electromagnetic waves, and the phenomenon of electromagnetic waves emitting or leaking into the air is called electromagnetic radiation. There is an electric field around any charged body, and the periodic change of the electric field will produce a periodically changing magnetic field, and there will be electromagnetic waves, which will produce electromagnetic radiation. So of course electromagnetic radiation exists.