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2-2. TV Signal Format
Standard Comparison Table
Signal Format
Active Lines
Sound
Aspect Ratio
Resolution
The digital TV standards allow several different formats. Broadcasters can choose between
three formats:
• 480p - The picture is 704 x 480 pixels, sent at 60 complete frames per second (480i is
also possible).
• 720p - The picture is 1280 x 720 pixels, sent at 60 complete frames per second.
• 1080i - The picture is 1920 x 1080 pixels, sent at 60 interlaced frames per second (30
complete frames per second).
(The "p" and "i" designations stand for "progressive" and "interlaced." In a progressive for-
mat, the full picture updates every sixtieth of a second. In an interlaced format, half of the pic-
ture updates every sixtieth of a second.)
The 480p and 480i formats are called the SD formats, and 480i is roughly equivalent to a nor-
mal analog TV picture. The 720p and 1080i formats are called the HD formats.
Some NTSC televisions can display a picture 720 pixels wide by 480 pixels high, that's a total
of 345,600 pixels. HD digital signals can have a maximum resolution of 1920 x 1080, that's
2,073,600 pixels, or six times more pixels than the older resolution. Pictures will be crisper and
cleaner, with more detail in every close-up and every panorama.
Analog (NTSC)
480i
Dolby Digital (5.1 ch)
Stereo (2 ch)
MPEG Audio (2 ch)
4 : 3
720 x 480
Digital (ATSC/DIRECTV)
SD
480p
720p or 1080i
Dolby Digital (5.1 ch)
4 : 3 or 16 : 9
640 x 480
1280 x 720
704 x 480
1920 x 1080
HD
16 : 9
10
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