Define PAL & NTSC

Broadcast television antenna receives free TV signals

NTSC and PAL are standards for analog broadcast television developed in the mid-20th century. Around the world, as countries rolled out their broadcast systems, each picked a national broadcast standard. NTSC and PAL, along with SECAM, became the primary standards for a half-century, until the advent of high-definition television. HDTV uses different standards.

Dawn of Television

Analog television ruled the roost for more than 50 years.

When television technology was commercialized in the United States during the 1930s, different geographic areas had different broadcast standards, all of which required different equipment to broadcast the signals and different televisions to receive them. To standardize broadcast specifications nationally and end consumer confusion, the Federal Communications Commission formed the National Television System Committee in 1940. This committee defined standards for broadcast signals and the equipment to broadcast and receive it. These standards became known by the name of the oversight body, abbreviated to NTSC.

Advent of Color Television

Color TV caught on in the 1950s and 1960s.

The original NTSC standard lacked provisions for broadcasting color signals. By the 1950s, the standard was updated to allow for color broadcasts, while maintaining backward compatibility with existing black-and-white signals.

In Western Europe the conversion to color television happened after the rollout of the modified NTSC system. The updated NTSC standard had many technical issues with color (NTSC was jokingly referred to as Never Twice the Same Color), and several European groups set about developing alternatives. Germany developed Phase Alternate Line, or PAL. France developed Sequential Color with Memory, called SECAM. None of these standards is compatible with any of the others, though you can get devices that will convert the signals for viewing or recording.

Technical Specifications

The original NTSC standard called for 525 lines of vertical resolution shown at 30 frames per second (for reference, movies are projected at 24 frames per second) in a 4:3 aspect ratio. The change to color broadcast required that part of the spectrum be used for the color signal, so the frame rate was reduced to 29.97 frames per second.

PAL and SECAM broadcast 625 lines of vertical resolution at 25 frames per second and a 4:3 aspect ratio.

The underlying NTSC and PAL technologies are similar, the main difference being that PAL uses a wider bandwidth to carry more color information, making the color more accurate.

Standards Around the World

North America, most of South America, Japan, South Korea and Taiwan adopted NTSC. Most of Western Europe, India, Iceland, Australia, parts of Africa and the Middle East, and a few countries in South America adopted PAL. SECAM was mainly adopted in France, Eastern Europe and parts of Africa.

HDTV

Digital TV is now the exclusive free U.S. television standard.

Since the mid-1990s much of the world has been adopting new broadcast standards for digital high-definition television. North America uses the ATSC standard, the majority of South America uses ISDB-T, while Europe, Australia, much of Asia, and parts of Africa use the DVB-T standard. Much of Africa and parts of Eastern Europe and Asia are still assessing the various options for HDTV standards.

References

• World Analog Television Standards
• Video Broadcast Standards
• Worldwide TV Standards