16
Understanding HDTV
What is Digital Television or DTV?
Digital TVs are televisions that can receive and display digital television broadcasts sent using any one of
three following categories: HDTV (High Definition TV), EDTV (Enhanced Digital TV), and SDTV (Standard
Definition TV).
What is the Difference Between HDTV, EDTV, and SDTV?
HDTV, EDTV, and SDTV are three grades of televison or monitors. They reference the maximum resolution
capability of a digital television or monitor to fully display digital broadcasts without having to “down-convert”
the actual signal content to fit the monitor’s display limitations. The resolution requirements for each of the
three DTV classifications and an explanation of the specifications are described below:
Vertical Res.
1
Horizontal Res.
2
Aspect Ratio
3
Scan Method
4
1080 lines
1920 dots
16:9 Wide
Interlaced
720 lines
1280 dots
16:9 Wide
Progressive
HDTV grade televisions and monitors are capable of displaying a maximum of either
1080 lines using interlaced scan method or 720 lines using progressive scan method.
Vertical Res.
1
Horizontal Res.
2
Aspect Ratio
3
Scan Method
4
480 lines
640 dots
4:3
Progressive
EDTV grade televisions and monitors are capable of displaying a maximum of 480 lines
using progressive scan method. All resolutions higher than 480 lines must be reduced
to 480 lines in order to be displayed. Progressive scan method reduces flicker;
however, picture quality may not necessarily outperform 480 interlaced when viewed at
normal viewing distances.
Vertical Res.
1
Horizontal Res.
2
Aspect Ratio
3
Scan Method
4
480 lines
640 dots
4:3
Interlaced
SDTV grade televisions and monitors are capable of displaying a maximum of 480
lines using interlaced scan method. All resolutions higher than 480 lines must be
reduced to 480 lines in order to be displayed.
1
Vertical Resolution (Scan Lines)
Vertical scan lines refer to the number of horizontal lines a TV or monitor can display to create an image.
As the number of lines increase, more information is displayed, resulting in better picture quality.
2
Horizontal Resolution
Each horizontal line in a TV or monitor is made up of individual dots (pixels). The higher the number of
pixels, the finer the TV picture becomes. Horizontal pixel measurements using today's technology can
range from 250 for a VCR to as much as 500 for a DVD player.
3
Aspect Ratio
Aspect ratio identifies the ratio of the TV screen's width over its height. A 16:9 aspect ratio refers to a
wide-screen picture format, while a 4:3 refers to a standard “square” TV format.
4
Scan Mode
Interlaced scanning is a method that creates a TV picture with alternating lines of information and is the
cause for flickering. Progressive scanning is a method that creates a TV picture with consecutive lines
of information that results in flicker-free picture quality.
USING WITH HDTV
Summary of Contents for PLMSDM1060
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