Paper Keywords Terrestrial Digital Television Broadcasting Engineering Practice
With the continuous progress of society and the rapid development of economy, people's living standards have been greatly improved. People's pursuit of food and clothing in the past has been upgraded to the pursuit of high quality and high quality living standards today. The improvement of people's living standard provides a good foundation for the development of terrestrial digital TV technology. Terrestrial digital TV is the general trend of TV technology development, and many countries in the world have begun to switch TV modes. This paper discusses the practical problems of terrestrial digital TV in radio and television engineering.
The continuous progress of society has brought about rapid economic development, but the rapid economic development has also brought about the continuous improvement of people's living standards. Therefore, people began to pursue a high-quality life. Because many countries have transferred analog TV to digital TV broadcasting, these countries have stopped broadcasting analog TV programs, which shows that terrestrial digital TV has achieved unprecedented development to some extent, and it has become an inevitable trend to apply terrestrial digital TV to radio and television projects. The author will briefly discuss the practical problems of terrestrial digital TV in radio and television engineering.
1 About terrestrial digital TV
The so-called terrestrial digital TV is a kind of digital TV technology. Terrestrial digital TV can watch TV programs by receiving various terrestrial digital TV signals sent by TV towers. The realization of terrestrial digital TV technology requires that TV sets have the ability to receive terrestrial digital TV signals. For the old analog TV sets in the past, if you want to receive terrestrial digital TV, you need a dedicated set-top box to receive it, and then the set-top box converts the received terrestrial digital TV signals into analog signals, and then connects them to the old analog TV set for viewing.
2 practical problems of terrestrial digital TV in radio and television engineering
2. 1 Practice of Digital Terrestrial Television in Antenna Positioning of Radio and Television Engineering
At present, most TV transmitting antennas are located in high transmitting towers (flat ground) in buildings and low transmitting towers in mountainous areas. In fact, the position of terrestrial digital TV antenna is extremely important. The choice of antenna address of terrestrial digital TV needs to consider many conditions such as local climate and topography. When the transmitting antenna is horizontally polarized in rainstorm season, the receiving effect of terrestrial digital TV antenna with good receiving effect will be worse. Therefore, when choosing the location of terrestrial digital TV, we should first test and analyze the received wireless signals, so as to see the change of receiving effect of terrestrial digital TV antenna in rainy days.
2.2 Practice of Terrestrial Digital TV Transmitting Antenna in Radio and Television Engineering
Radiating electromagnetic waves into space is an important function of the transmitting antenna. The electromagnetic wave here is composed of alternating magnetic field and electric field. It is stipulated in the project that the polarization direction of antenna is expressed by the direction of electric field, which is for the convenience of analysis. Therefore, the antennas we usually use are often single-polarized.
Because the horizontally polarized antenna has a good far-field intensity distribution, in the traditional analog TV wireless coverage, considering the unobstructed line-of-sight propagation mode of electric waves, we usually adopt the way of hanging from a tower or a mountain, while the horizontally polarized antenna has a good far-field intensity distribution and achieves one of the purposes of covering a wider range under the same transmission power, so the transmitting antenna is often a horizontally polarized antenna. However, it should be noted that the near-field intensity distribution of horizontally polarized antenna is worse than that of vertically polarized antenna, and it is even worse in the environment with water, humidity and trees. This phenomenon is also caused by polarization deflection of horizontally polarized antenna. Therefore, the near-field receiving effect of vertically polarized antenna is better than that of horizontally polarized antenna in general or in special environment such as water, humidity and woodiness.
2.3 Practice of Terrestrial Digital TV in the Installation of Receiving System of Radio and Television Project
In the installation of terrestrial digital TV receiving system in the practice of radio and television engineering, the mobile receiving terminal of terrestrial digital TV is mainly vehicle-mounted. Based on the operation modes of Shanghai and Singapore, the author thinks that the installation of terrestrial digital TV receiving system should first consider the platform of urban public transport. However, in the public transportation of major cities in China, buses on all bus lines are often in a state of power shortage. If mobile TV terminals are installed on these buses to receive this equipment, the power consumption of buses will increase. With the increase of bus electricity consumption, the phenomenon of bus power shortage will become more serious, which will make it difficult for buses to operate normally. Therefore, when installing the terrestrial digital TV receiving system, the mobile TV terminal receiving equipment should be installed on the bus or tram powered by diesel.
3 Conclusion
This paper first gives a brief introduction to terrestrial digital TV, and then discusses the practical problems of terrestrial digital TV in radio and television engineering from three aspects: antenna position, transmitting antenna and receiving system installation.
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