The most important issue for consumers who buy HDTV is the signal source. At present, most TV signals in the country are still wired transmission, and the signal test analog signal, which is of course not HD signal, even using analog signal. Looking at widescreen is not as good as ordinary CRT TV. But now there are several new signal transmission technologies that can implement high-definition digital TV.
This article refers to the address: http://
Wired signal transmission
"Cable TV" is a term we are very familiar with. For more than a decade, we have been using this method of transmitting signals over a radio frequency line to watch TV programs. At present, more than 90% of urban residents watch TV signals by means of wired transmission. The first batch of replacement set-top boxes also used this connection method, but changed the "white line" from the past direct-connected TV to the first set-top box, and then the set-top box was transferred to the TV set via component or AV cable. Of course, the use of cable-transmitted digital TV signals is the least expensive way, just add a set-top box.
Schematic diagram of cable digital TV transmission
However, there is a misunderstanding. Consumers think that the program that is watched after adding a set-top box is a high-definition TV program. The TV program that was originally transmitted by cable is still an analog signal. Adding a set-top box only turns the analog signal into a digital signal, and watching the widescreen. Time will not be deformed. Now there are several digital HD signal TV programs being tested, which are only being tested. After the official division of digital HDTV, it is expected to charge a corresponding fee.
Terrestrial digital television signal transmission
Due to the restriction of terrestrial digital television signal transmission, this method needs to establish a transmitting station at a distance along the transmission to ensure the strength of the signal, which is not applicable in remote areas. At present, terrestrial digital TV is still in the pilot stage, and only CCTV HD is a channel. However, it is ideal for clarity and signal strength.
Ground digital TV transmission mode
"Ground digital TV" is probably the most popular digital TV transmission method. Nowadays, some brands have added modules for terrestrial digital TV. Consumers only need to buy such a TV or buy a terrestrial digital set-top box to watch.
Terrestrial digital television is similar to the early years of wireless television, which is covered by a signal from a television station tower to cover a certain range. Common is the LCD TV on the bus.
Satellite television transmission
Then there is "satellite TV". Satellite TV transmission is developed on the basis of satellite communication. It is on a geostationary satellite at 35800KM above the Earth's equator. The transponder and antenna system are loaded to the ground to broadcast radio and television signals, directly to a large area. A technology covered by radio and television. The star of Zhongxing No. 9 satisfies the requirements of satellite digital TV transmission for satellites.
Satellite TV transmission diagram
Satellite TV is almost everywhere, and the "big pot" that stands on the roof is a satellite signal receiver. After the connection is completed, the control of the received TV box can be adjusted to the corresponding frequency band to watch the digital signal transmitted by the satellite.
Written in the end: Understand the information of many of these TV signals, you should be able to see the "digital HD TV" is pinned down. The TV itself has met the requirements for playing HDTV, but the high-priced flat-panel TV has almost the same clarity as the traditional CRT TV, and there is also a display scale problem.
I believe that the technology of digital transmission TV signals in China will develop rapidly, but it will take time. I hope that consumers can see this problem. When buying TV, I think it is good to buy a CRT TV at a low price and then replace it or buy a high-definition TV in a step-by-step manner.
The self-adhesive fabrics are coated with PTFE and have a layer of silicone or acrylic adhesive. The silicone adhesive fabric have a continuous operating temperature range between -70℃ and +240℃. The acrylic adhesive fabrics serves from -40℃ and +150℃ while it offers a very high initial adhesive power and a excellent solvent resistance.
Characteristics:
·easy to apply
·excellent high temperature resistance
·waterproof
·non-poisonous
Adhesive Tapes,Sealing Plastic Film,Sealing Adhesive Tape,Double Sided Adhesive Tape
TAIZHOU YAXING PLASTIC INDUSTRY CO., LTD , https://www.yaxingptfe.com