Chapter 2 : Basics of HDTV

The first step in knowing the essentials you need to consider before buying the HDTV is to become familiar with its basics. The following passages will let you understand what is HDTV, how does it work, and what is the future of HDTV.

What is HDTV?

HD stands for high definition, and it is the new standard of television viewing. HDTV is actually part of the Digital Television (DTV) specifications brought by the Advanced Television Systems Committee (ATSC). ATSC has defined eighteen different transmission formats, out of which six are considered ‘High Definition,’ because they constitute an incredible improvement over the resolution quality of a normal television.

HDTV has 1125 lines of resolution in comparison to 525 lines in the Regular NTSC analog signals. Thus, HDTV carries over five times the video information, as compared to your conventional NTSC analog TV set. In one way, it is the biggest advantage, and the other way it creates a hurdle because HDTV transmission requires an extraordinary bandwidth, five times the capacity of a conventional TV signal. True, they are five times better than your conventional TV, but then, they are 50% more expensive also.

A Brief History of HDTV

Although HDTV has a very short history, in it has been playing a major role in the transformation of digital home entertainment space. The credit goes to the satellite TV service providers, who have made HDTV such a hot cake today.

It all started almost 15 years ago in 1987, when FCC (The Federal Communications Commission) issued a rule stating that that HDTV standard must be compatible with existing NTSC service. However, later in 1990, General Instrument Corporation proposed for an all-digital HDTV system. By the end of 1990, four serious contenders in the United States, ATRC, Zenith HDTV, AT&T, and MIT, announced their digital entry in HDTV system. Then 1993 was a remarkable year in the history of HDTV in the US, when a grand Alliance was formed. The alliance included major players such as, AT&T, GI, MIT, Phillips, Sarnoff, Thomson, and Zenith. Their task was to take the best features from the four HDTV systems and develop a standard HDTV system. They successfully tested it in 1995 and the FCC set it as the HDTV standard.

How Does HDTV work?

You can receive HDTV signals in your home through any of the three broadcast systems, over the air through antenna, cable, and satellite. Although some hurdles regarding digital broadcasting remain unaddressed, they would be addressed soon. For digital broadcasting, a show is first recorded in HD format using HD cameras and equipments. Then, it is distributed digitally over the air, cable or satellite. Now, you just need an HDTV-compatible TV with a HDTV tuner or receiver to decode the digital signal. That is it. Your HDTV is ready. Sit back and enjoy.

Antenna, Digital Cable or Satellite?

Antenna is free of monthly charges, but you will be able to watch the broadcast channels only. You will have to perform certain antenna gymnastics to watch other channels. However, if you can afford a HDTV, you can use cable or satellite as well. If you choose to go with satellite option, you must see if you would get line of sight to the satellite. Sometimes, the beam from the satellite is blocked, for example due to a gigantic tree in your neighborhood. You need to place the satellite dish with a clear view of the northern sky. Therefore, it is highly advisable to visit your neighbors and see how their HDTVs are functioning. 

Analog, Digital and HDTV- A Comparison

Analog: For years, watching TV has involved analog signals. The signal is made of continuing varying radio waves that the TV translates into pictures and sounds. These signals reach your TV over the air, through a cable, or via satellite. Obviously, it can show only standard-definition program such as those found on regular TV, direct TV, Dish TV, cable or satellite.

Digital: Digital television is better known as DTV. A digital signal transmits the information for video and sound as ones and zeroes instead of a wave in a digital format. Digital television has certain advantages over analog. For example picture quality of digital TV is always better irrespective of the size of the screen. It allows multi-casting, and TV stations can broadcast several signals using the same bandwidth. It can also display progressive-scan DVD and can support HDTV broadcast as well.

HDTV: HDTV is by far the most common and advanced form of digital television. It can display almost everything including standard TV, progressive-scan DVD, and HDTV signals.

Issues with HDTV

Distribution

There are two kinds of advocates for HDTV systems. One who feel that HDTV will ultimately be successful outside the conventional channels. Others who feel HDTV is capable and it must use the existing conventional channels. However, there are two options available to cable TV companies. Either they can continue to broadcast conventional NTSC by installing 20 MHz MUSE-type HDTV systems, or they can go with the digital grand aliens systems. This leads to two interesting possibilities of two different HDTV standards – one for terrestrial broadcast and other for cable broadcast.

Bandwidth Limitations

HDTV means a bandwidth of 18 MHz. Therefore, if you decide to move on to HDTV there is a problem, since the current terrestrial channel allocations are limited to 6 MHz only. This way there are three options available to terrestrial broadcast. First, to change the channel allocation system from 6 MHz to 20 Mhz; second, to compress the HDTV signal to fit inside the 6 MHz; and third, to allocate multiple channels for the HDTV signal. Out of the three options, only the third one allows compatibility.

HDTV: Myths and Realities

There are so many things to consider before buying a HDTV, given the significant amount of confusions it has created. Most of them are simply myths. We have tried to cover some common concerns regarding HDTV.

Myth: DTV is the same as HDTV

Reality: No. DTV is just another term for Digital TV. DTV is a technology, in which signal is broadcast or received digitally. HDTV is one type of DTV transmission. Where DTV improves picture and sound over analog signals, HDTV offers the highest resolution picture and sound, all digitally.

Myth: Digital cable is the same as HDTV

Reality: No. Digital cable is just an improvement of picture and sound quality over regular analog cable, but in no way it is of high definition.

Myth: Non-HDTV programs cannot be viewed in HDTV

Reality: It is not completely true. You can watch non-HDTV programs on HDTV, but picture quality will suffer a little. Black and gray bars may appear on the left and right side of the screen to set the image in 4:3 aspect ratio.

Myth: We need to fiddle with a switch or wire when changing from satellite to antenna signal.

Reality: The HDTV automatically detects a HDTV station, whether it is being received via antenna or satellite. You just have to use the remote control to change channels.

Myth: All Digital TVs are HDTV compatible

Reality: No, this is not true. Not all Digital TVs are HDTV compatible.

Myth: The quality of HDTV varies with satellite, cable, and antenna

Reality: Quality of picture remains the same irrespective of whether you are receiving signals through antenna, cable or satellite.

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