Question 2: What does the outer grid line of the closed route do? The closed outer network cable plays the role of shielding electromagnetic radiation interference;
The signal line of CCTV is divided into two parts: the signal line core and the shielding layer. The hard one in the middle is used as the signal, and the wire core and tin foil in the outer layer are used as the signal shielding layer, which plays an anti-interference role.
Cable TV is very popular in Canada, the United States, Europe, most Asia-Pacific regions and many Asian countries, although it has not been greatly improved in many South America, the Middle East and Africa, because it is quite uneconomical to lay cables in these areas, especially in South Africa, where so-called "wireless cables" or microwave-based systems are used, and "direct-to-home" satellite TV is more common.
Like wireless broadcasting, many channels can be transmitted in one cable using different frequencies without interfering with each other. A TV tuner, video recorder or radio can select channels from mixed signals.
Question 3: What's the use of cable TV? What's the difference between cable TV and antenna? The function of CATV is to transmit the signal of CATV. It is connected with cable TV. Compared with ordinary antenna, it is thicker, but it is coaxial cable. The antenna only transmits wireless signals. I really look forward to helping you adopt it.
Question 4: Is it necessary to have a closed circuit when using a digital set-top box? Not necessarily.
There are many kinds of digital set-top boxes.
If it is a one-way set-top box, there must be a closed line.
If you have a network function, or even a pure network set-top box, you can use some or all of the functions without turning off the line.
Even if it is a one-way set-top box, if it has local playback function, it can also use a USB flash drive without closing the line.
To put it simply, if you want to watch the digital TV live broadcast of radio and television, you have to have a closed route. Otherwise you don't need it.
Question 5: There is a net layer in the TV closed circuit, which is used for shielding. What signal will affect the closed-circuit signal? The line at home is called -5 line. Find the 1-5 head and the corresponding hoop, first thread the hoop on the line, and cut the plastic ring outside by half an inch with scissors. Be careful not to cut short the mesh. A good wire has a layer of tin foil outside the mesh, which can be cut off. Turn the net down and cut off the exposed plastic core by half an inch. Be careful not to cut the copper core from the middle. Insert the copper core into the five heads, and the edges of the heads should be inserted into the coaxial line along the inner wall of the network cable. Put the hoop on the turned net and fix it with a vise, so that the head is done. Note that the metric head is generally used for transmission lines, and the British head is used for some set-top boxes, which is slightly smaller. It will be loose, which may affect the shielding effect.
Question 6: What are the functions of a copper wire inside a closed circuit and a network wire outside? It is very important that the copper wire inside transmits signals and the network wire outside plays a shielding role. The network should be grounded during operation.
Question 7: What kind of cable has the same function as wire closing? Find a coaxial cable with other colors RG-59 and 75 ohms (Ω) within 50 minutes, and try to dye the cable with other colors of paint.
Question 8: What is the use of mainland radio and television in promoting digital TV? Under the slogan touted by XX leaders, the analog will be quickly converted into digital TV. On the surface, it is to improve the picture quality and facilitate management. In fact, it is to monopolize, and it is forbidden for multiple TVs to share a signal source, which is convenient for radio and television to get money from it. Do you think that a garbage monopoly like Tianchaoguang Electric Power Company will serve the people just to raise a group of idle people?
A low-tech redundant device like a set-top box can make you pay if it is monopolized by the mainland. .
Hong Kong doesn't have to pay radio and television viewing fees at all, and people don't have to buy any junk set-top boxes at all. Television sets in Hong Kong are equipped with wireless digital terrestrial wave receivers, so you can watch high-quality programs by connecting antennas. What kind of bird is the mainland? High definition is not popular yet, and the standard definition is still 4: 3, so the flat panel will be deformed, and you have to buy high-priced junk program packages of radio and television. .
At present, only Hong Kong and Japan really use high-definition terrestrial digital TV broadcasting. Because of the monopoly of radio and television, the mainland can only use its own digital set-top box, and the price is determined by radio and television. Most wireless terrestrial waves are only used to insert junk shanzhai advertisements, which increases the income of radio and television.
Television stations in Hong Kong have more advanced relay equipment and higher signal rate, so the picture quality is clearer. .
Question 9: What's the name of the cable used in cable TV? The cable for CATV is called four-shielded RF cable, which is a new product in recent years. It is made of two layers of metal mesh and two layers of aluminum foil. The shielding effect is much better than the past two-layer shielded wire (one layer of metal mesh and one layer of aluminum foil). In the process of use, the four layers of shielding are all playing a role, and it cannot be said which layer is used or useless. If you want to connect these four layers of shielding nets at the joint, you must use a joint that matches the four shielding wires. If you only have a connector with double shielded wires, you only need to touch two layers of metal mesh (aluminum foil always touches the corresponding metal mesh).
Question 10: What is the use of LCD TV cable TV interface? At present, China has not been fully digitized, so it is generally used, and the RF input port is still reserved for analog TV or analog cable TV users.