Cisco ISB7000, Руководство по установке

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Picture Formats
What Is the Diff erence Between a Standard-Screen and a
Wide-Screen HDTV?
The type of screen your HDTV has (wide-screen or standard-screen) determines how the set-top
displays programs on the screen. The picture format for an HDTV is a combination of
aspect ratio
and screen resolution and is diff erent for standard-screen and wide-screen HDTVs.
What Is Aspect Ratio?
An aspect ratio is the ratio of the width to the height of the TV screen. The aspect ratios diff er
because the television industry manufactures both standard-screen and wide-screen HDTVs to
appeal to consumer viewing preferences.
What Is the Screen Resolution?
The screen resolution indicates the amount of detail that the picture displays. Resolution is identifi ed
by the number of display lines on the screen. The techniques that an HDTV uses to “paint” the
picture on the screen are referred to as progressive and interlaced.
With the progressive scanning method, the lines are drawn on the screen one at a time in
sequential order. Progressive scanning results in a more detailed image on the screen and is also less
susceptible to the fl icker commonly associated with interlaced scanning. The
interlaced method
involves refreshing pixels in alternation — fi rst the odd lines and then the even lines.
For advanced setup, select the screen resolution that your TV can support. Refer to your HDTV user
manuals to choose the proper screen resolution (480i, 720p, 1080i, or 1080p) for your setup.
For example, a screen resolution of 1080i indicates that the screen shows 1080 lines in an
interlaced display, and 720p indicates that the screens shows 720 lines in a progressive display.
A standard-screen HDTV has a 4x3
aspect ratio. The screen is 4 units wide
for every 3 units tall.
A wide-screen HDTV is one-third wider
than a standard-screen HDTV. The screen is
16 units wide for every 9 units tall.
A screen resolution of 480i fi lls the
screen. A screen resolution of 720p or 1080i
fi lls the screen.
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