DirecTV H20 用户指南

 Resolution &  Interlacing

Two elements that determine the quality of a TV picture are:

If you’ve ever looked very closely at your TV, you have noticed the picture is actually made up of many 

lines scanning across the screen. Th

  e set of lines that make up a complete image are called a “frame.” 

For TV equipment and broadcasts, resolution is defi ned by the number of horizontal lines displayed 

to make up each frame of a video image. Th

  e more lines of resolution used to compose each frame, the 

more detailed and sharp the picture. Standard TV resolution uses 480 horizontal lines to make up each 

video frame;  HDTV uses either 720 or 1080 lines to compose each frame. 

Th

  e term “interlacing” refers to whether each of those frames contains all of the lines of image, or every 

other line. Interlaced signals take every other line from 2 frames, each lasting 1/60th of a second, and 

combine them into one frame lasting 1/30th of a second. In this way, interlacing tricks the eye into 

thinking it’s seeing twice the resolution that’s actually being displayed. In non-interlaced video, referred 

to as “progressive scan” video, frames are displayed every 1/60th of a second containing all of the lines 

of video information.

Th

 e specifi cations for video resolution are usually stated by giving the number of horizontal lines (480, 

720 or 1080, as described above) followed by either the letter “i” (for interlaced) or “p” (for progressive 

scan). Most standard TV broadcasts are 480i; some DVDs and non- HDTV digital broadcasts use 

480p. Specifi cation for  HDTV broadcasts and equipment requires either 1080i or 720p.

If your 
DIRECTV was 
professionally 
installed, you 
can skip this 
section.