Glossary

Tv Glossary

Standards

Screens

Signals

Stations

DTV formats

VIDEO BROADCAST STANDARDS
Standard Definition Television

Most countries around the World have had in use for many years, one of three main television broadcast standards.
These three main standards are NTSC, PAL and SECAM. However, each standard is
not compatible with the other. The charts below give a description of each standard
and the technical variations within each.

The first color TV broadcast system was implemented in the United States in 1953. This was based on the NTSC (National Television System Committee) standard. NTSC is used by many countries on the American continent as well as many Asian countries including Japan. NTSC runs on 525 lines/frame.

SYSTEM	NTSC M
Lines/Field	525/60
Horizantal Frequency	15.734 kHz
Vertical Frequency	60 Hz
Colour Subcarrier Frequency	3.579545 mHz
Video Bandwidth	4.2 mHz
Sound Carrier	4.5 mHz

The PAL (Phase Alternating Line) standard was introduced in the early 1960's and implemented in most European countries except for France.
The PAL standard utilizes a wider channel bandwidth than NTSC which allows for better picture quality. PAL runs on 625 lines/frame.

The SECAM (Sequential Couleur Avec Memoire or Sequential Colour with Memory) standard was introduced in the early 1960's and implemented in France. SECAM uses the same bandwidth as PAL but transmits the color information sequentially.
SECAM runs on 625 lines/frame.

Compared to standard television (NTSC), the true HDTV image has twice the luminance definition - vertically and horizontally - and is twenty-five percent wider. Standard television aspect ratio is 4:3 (four units wide, three units high) - the HDTV aspect ratio is 16:9. The 16:9 ratio is much closer to the average wide-screen image shown in movie theaters. The biggest difference, and the greatest appeal of HDTV, is its clarity. True HDTV pictures are composed of 1080 active lines (1125 total) whereas current standard television pictures are composed of only 480 active lines (525 total). While it is possible to see the lines that make up standard television pictures, HDTV lines are not at all noticeable. The fine-grained HD picture contains five times more information than does the standard television picture and is accompanied by multi-channel, CD quality sound. The difference in video and sound quality is dramatic.

TV Formats:

• 480i - The picture is 704x480 pixels, sent at 60 interlaced frames per second (30 complete frames per second).
• 480p - The picture is 704x480 pixels, sent at 60 complete frames per second.
• 720p - The picture is 1280x720 pixels, sent at 60 complete frames per second.
• 1080i - The picture is 1920x1080 pixels, sent at 60 interlaced frames per second (30 complete frames per second).
• 1080p - The picture is 1920x1080 pixels, sent at 60 complete frames per second.
  
  

  HDTV is part of several standards incorporated in digital television or DTV. Basically, DTV is composed of three separate standards:
  

  • HDTV 1080 (1080 lines of resolution, 16:9 aspect ratio)
    
  • HDTV 720 (720 lines of resolution, 16:9 aspect ratio)
    
  • SDTV (480 lines of resolution, 16:9 or 4:3 aspect ratio)
    
    
    

    United States major market television stations began transmitting DTV in the fall of 1998. The number of new DTV stations on the air is increasing every month. By the year 2008, all United States television stations will be converted to DTV.