Read the text and translate it: TV Goes Digital

The term "digital TV" is used in many different ways right now, depending on whom you're talking to. There's also the term "HDTV," which is the most advanced form of digital TV in use in the United States. The reason it gets confusing is because digital TV in the United States combines three different ideas.

The first idea that is new to digital TV is the digital signal. Analog TV started as a broadcast medium. TV stations set up antennas and broadcast radio signals to individual communities. You can attach an antenna to your TV and pick up channels 2 through 83 for free. Digital TV started as a free broadcast medium as well. For example, in San Jose, Calif., you can tune in to about a dozen different commercial digital TV stations if you have a digital TV receiver and an antenna broadcasts, so until the digital transition is complete, each broadcaster has an analog TV channel and a digital TV channel. The digital channel carries a 19.39-megabit-per-second stream of digital data that your digital TV receives and decodes. Each broadcaster has one digital TV channel, but one channel can carry multiple sub-channels if the broadcaster chooses that option.

Here's how it works: On its digital channel, each broadcaster sends a 19.39-megabit-per-second (Mbps) stream of digital data. Broadcasters have the ability to use this stream in several different ways. These streams are called sub-channels, and this type of broadcasting is called multicasting. The reason that broadcasters can create sub-channels is because digital TV standards allow several different formats. Broadcasters can choose between three formats.

(The "p" and "i" designations stand for "progressive" and "interlaced." In a progressive format, the full picture updates every 60th of a second. In an interlaced format, half of the picture updates every 60th of a second.)

The 480p and 480i formats are called the SD (standard definition) formats, and 480i is roughly equivalent to a normal analog TV picture. When analog TV shows are upconverted and broadcast on digital TV stations, they're broadcast in 480p or 480i.

The 720p, 1080i and 1080p formats are HD (high definition) formats. When you hear about "HDTV," this is what is being discussed -- a digital signal in the 720p, 1080i or 1080p format.

Finally, the HD formats of digital TV have a different aspect ratio than analog TVs. An analog TV has a 4:3 aspect ratio, meaning that the screen is 4 units wide and 3 units high. For example, a "25-inch diagonal" analog TV is 15 inches high and 20 inches wide. The HD format for digital TV has a 16:9 aspect ratio.

Many countries are replacing over-the-air broadcast analog television with digital television to allow other uses of the radio spectrum formerly used for analog TV broadcast. Digital television supports many different picture formats defined by the combination of size, aspect ratio and interlacing. There are a number of different ways to receive digital television. One of the oldest means of receiving DTV is using an antenna. DTV images have some picture defects that are not present on analog television or motion picture cinema, because of present-day limitations of bandwidth and compression algorithms such as MPEG-2. This defect is sometimes referred to as "mosquito noise". Because of the way the human visual system works, defects in an image that are localized to particular features of the image or that come and go are more perceptible than defects that are uniform and constant. However, the DTV system is designed to take advantage of other limitations of the human visual system to help mask these flaws, e.g. by allowing more compression artifacts during fast motion where the eye cannot track and resolve them as easily and, conversely, minimizing artifacts in still backgrounds that may be closely examined in a scene (since time allows).

 

 

Post-text exercises:

1. Put the words in the right order to make a sentence:

1. Broadcast, analog, TV, as, medium, started. 2. Antenna, you, TV, can, your, to, attach, an. 3. Each broadcaster has one digital TV channel. 4. Choose, between, broadcasters, can, formats, three. 5. HD, has, the, ratio, format, digital, for, a, aspect, 16:9. 6. Broadcaster, has, one, digital, each, TV channel. 7. Can, program, broadcaster, at, a, send, Mbps, single, 19.39. 8. The, a, HD, ratio, than, formats, of, analog, digital, have, aspect, different, TV, TVs. 9. Broadcasters, the, use, have, stream, in, to, of, digital, data, different, several, ability, ways. 10. TV, digital, as, broadcast, free, started, a, medium.

2. Fill in the blanks with the following words:

Idea, antennas, broadcaster, ability, signals x2, formats, antenna, digital, data, medium

1.The first...that is new to digital TV is the digital signal. 2. Analog TV started as a broadcast... 3. TV stations set up... and broadcast radio signals to individual communities. 4. You can attach an... to your TV and pick up channels 2 through 83 for free. 5. The digital channel carries a 19.39-megabit-per-second stream of digital... that your digital TV receives and decodes. 6. Each broadcaster has one... TV channel. 7. One channel can carry multiple sub-channels if the... chooses that option. 8. Broadcasters can choose between three....9. Broadcasters have the... to use this stream in several different ways. 10. DTV is the transmission of audio and video by digital..., in contrast to the analog... used by analog TV.

3. Say if the following statements are true or false:

1. Digital TV in the UK combines three different ideas. 2. Analogue TV started as a broadcast medium. 3. Each broadcaster has two digital TV channels. 4. Digital TV started as a free broadcast medium as well. 5. An analog TV has a 4:3 aspect ratio.

6. Digital TV in the United States combines two different ideas. 7. Broadcasters have the ability to use stream in the same ways. 8. The analog channel carries a 19.39-megabit-per-second stream of digital data. 9. Digital TV standards don’t allow several different formats. 10. DTV images don’t have picture defects.

4. Put the questions to the following sentences:

1. The term "digital TV" is used in many different ways right now. 2. The picture is 1920x1080 pixels, sent at 60 complete frames per second. 3. The term "HDTV," is the most advanced form of digital TV in use in the United States. 4. The FCC gave television broadcasters a new frequency to use for their digital broadcasts. 5. A broadcaster can divide the channel into several different streams. 6. The HD format for digital TV has a 16:9 aspect ratio. 7. Broadcasters have the ability to use stream of digital data in several different ways. 8. Digital TV in the United States combines three different ideas. 9. Digital television can provide many-to-one, many-to-many, and one-to-one communication.10. Digital TV will allow viewers to interact with game shows, ask questions during cooking shows, or call up purchase information regarding featured products.

5. Complete the following sentences:

1…which is the most advanced form of digital TV in use in the United States. 2. When analog TV shows are unconverted… 3… broadcast radio signals to individual communities. 4… this is what is being discussed -- a digital signal in the 720p. 5.The FCC gave television broadcasters a new frequency to use for their digital…6.… you can tune in to about a dozen different commercial digital TV stations… 7. Digital TV in the United States combines... 8.... is the most advanced form of digital TV in use in the United States. 9.... sends a 19.39-megabit-per-second (Mbps) stream of digital data.

6. Match the first part (1-8) of the sentence with the second part (a-h):

1. Frequency is …

2. A sensor is …

3. Digital television (DTV) is …

4. A television channel is …

5. A decoder is …

6. Light or visible light is …

7. Intensity is ….

8. A tuner is ….

a) a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument.

b) … a physical or virtual channel over which a television station or television network is distributed.

c) … a device which does the reverse of an encoder, undoing the encoding so that the original information can be retrieved.

d) … the number of occurrences of a repeating event per unit time.

e) … the transmission of audio and video by digital signals.

f) … a measure of the energy flux, averaged over the period of the wave

g) … a circuit module or free-standing equipment which detects electrical signals and converts them to a form suitable for further processing.

h) … the portion of electromagnetic radiation that is visible to the human eye, responsible for the sense of sight.

7. Read the supplementary text, translate and entitle it:

A DTV receiver is a set-top box that permits the reception of Digital television. Its components are very similar to a desktop PC. The DTV receiver is a vital link in the chain of television system. The goal of a broadcasting system is to concentrate the hardware requirements at the source to simplify the receivers and makes it as inexpensive as possible.

It is usually connected to the TV set or incorporated in the TV set. The main features of a DTV receiver may be classified as follows:

decodes the incoming digital signal;

verifies access rights and security levels;

displays cinema quality pictures on the TV set;

outputs digital surround sound;

processes and renders Internet and interactive TV services.