The standard
for broadcasting picture and sound using digital signals, DTV allows
for dramatic improvements in both picture and sound quality versus
conventional NTSC analog programming. DTV programming can be delivered
in two basic formats: standard analog definition (SDTV) or high
definition (HDTV).
DTV Format Comparison
Transmission Type
Analog
Digital
Digital
Digital
Digital
NTSC
Standard Definition
Standard Definition
High Definition
High Definition
Maximum Resolution
480i
480i
480p
720p
1080i
Aspect Ratio
4:3
4:3
4:3 or 16:9
16:9
16:9
Channel Capacity
1
5-6
5-6
1-2
1
Description
Standard TV as we know it today
Good Picture and Sound —DVD or DBS Quality
Better, depending on source; can be outstanding
Best Possible
Best Possible
The highest form of digital television, delivering
up to 1,080 scan lines, HDTV produces images that go beyond anything
you've ever seen in a home environment. SDTV, or Standard Definition
Television, is also a dramatic improvement over today's TV, with
the added benefit of allowing stations to broadcast multiple programs
within the same bandwidth as an HDTV signal.
DTV Format Detail
ScanLines
Scan Rate
Pixelization
Frame Rate
Aspect Ratio
Formats
SDTV
525 total
480 active
15.75 kHz (60i)
480 x 640
24p, 30p, 60p or 60i fps
4:3
4
525 total
480 active
31.5 kHz (60p)
480 x 704
24p, 30p, 60p or 60i fps
4:3 or 16:9
8(4x2)
HDTV
750 total
720 active
45 kHz
(60p)
720 x 1080
24p, 30p, 60p
16:9
3
1125 total
1080 active
33.75 kHz
(60i)
1080 x 1920
24p, 30p, 60i
16:9
3
Adopted DTV
formats also include both interlaced and progressive broadcast and
display methods.
Interlaced Scanning: The frame/picture is made
up of two fields
—consisting of 525 lines (480 viewable) or 1125 lines (1080
viewable)
All odd numbered lines are scanned on the screen in 1/60th of
a second
All even numbered lines are scanned on the screen in 1/60th
of a second
This presents an entire picture in 1/30th of a second
Progressive Scanning : The frame/picture is made up of one
field
—consisting of 525 lines (480 viewable) or 765 lines (720 viewable)
All horizontal lines are scanned in succession in a single pass
This presents an entire picture in 1/60th of a second (twice
as fast as interlaced)
Where is DTV programming?
Right now, a little over 50% of American homes have access to digital
television through the four major networks. By 2002, 100% of all
commercial stations will offer digital programming. And according
to FCC mandate, all U.S. television stations must begin digital
broadcasting by 2003, and be exclusively digital by 2006. It's time
you went digital. It's in your future.
