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High Definition TV (HDTV) Fundamentals


DIGITAL TELEVISION
Almost all television's manufactured since 2007 have a built-in digital tuner, or more accurately an ATSC tuner, for receiving over-the-air TV. Some digital televisions do not use a low noise receiver (common in analog TV's), and may not get some weaker signals. One reason not to use a low noise receiver is to cut cost, another is satellite and cable TV does not (usually) require a low noise receiver.

HDTv Set
INDUSTRY STANDARDS
ATSC - Advanced Television System Committee -- Digital TV
NTSC - National Television System Committee -- Analog TV

See the ATSC Website for a list of downloadable specifications.

A few digital TV's can only receive signals from a cable or satellite TV box (or camera, video game, computer). These TV's are video monitors only and do not receive over-the-air signals. Note that most ATCS equipped televisions can also be used as video monitors.

Common Television Labels
  • Digital Tuner
    • ATSC
    • HDTV
    • EDTV
    • SDTV
    • HiDef
  • Analog Tuner
    • NTSC
  • Video Monitor
    • HD-Ready
    • Digital-Ready
    • Digital Monitor

Many digital televisions can process both digital and analog signals (ATSC and NTSC), allowing the television to display analog DVD's, VCR's, and older video games.

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Standard and High Definition
Over-the-air digital television can broadcast sub channels in high definition HDTV (720p, 1080i, 1080p), or standard definition (480i, 480p) resolution. The number is resolution in pixels per inch. The letter " p " stands for Progressive, picture lines are displayed one after the other. The letter " i " stands for Interlaced, odd picture lines displayed then even lines. High definition uses a wide screen aspect ratio of 16:9, or a square ratio of 1:1. Standard definition uses a ratio of 1:1, 4:3, or 16:9. The frame rate in North America is 23.976, 24, 29.97, 30, 59.94, and 60 frames per second (fps). The old analog TV system displayed an interlaced (i) picture, had an aspect ratio of 4:3, and a frame rate of 30 fps. Most Hollywood movies run at 24 fps.

Broadcast DTv Display Types
ATSC Document A/53 Part 4:2009
Definition Resolution
H x W (PPI)
Aspect
Ratio
Frame
Rate
High
Definition
(HDTV)
1080p 1080 x 1920 16:9
1:1
24 fps(1)
30 fps(2)
1080i 30 fps(2)
720p 720 x 1280 24 fps(1)
30 fps(2)
60 fps(3)
Standard
Definition
(SDTV)
480p 480 x 704 16:9
4:3
24 fps(1)
30 fps(2)
60 fps(3)
480 x 640 4:3
1:1
480i 480 x 704 16:9
4:3
30 fps(2)
480 x 640 4:3
1:1
Frame Rate
(1)
(2)
(3)
24 or 23.976
30 or 29.97
60 or 59.94
fps
fps
fps
Aspect Radio
16:9
4:3
1:1

H = height, W = width, PPI = pixels per inch.

The ATSC Digital TV Standards include HDTV, SDTV, data broadcasting, multichannel surround sound audio, and satellite direct-to-home broadcasting.

Ultra High Definition (UHD) / 4k resolution (next-Gen TV)
Stations will continue to broadcast using the current standard (ATSC 1.0), but will have the option to simulcast on another frequency an Ultra High Definition signal (ATSC 3.0). The UHD signal will have higher resolution (3840 x 2160), great for extremely large screens, but of little value to small and moderate size screens. UHD will also have high dynamic range which changes colors faster for a better picture, and a maximum frame rate of 120 fps.. Additionally, UHD will have better reception by using new techniques that allow for a lower signal-to-noise ratio. UHD may catch on, or may go by the way of quadrophonic FM radio.

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High Definition TV (HDTV) Fundamentals
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