What is NTSC (National Television Standards Committee)?

NTSC (National Television Standards Committee) is an encoding/transmission system for analog color television, which was developed in the United States in the 1940s and is widely used in the United States and Japan.

What is the NTSC Video Format?

A variant of NTSC is the PAL video system used in Europe and some countries in South America.

The NTSC television system consists of an extension of the North American monochrome system. Its development started in the late 1930s by CBS (Columbia Broadcasting System). However, this development was approved by the FCC in the 1950s.

This system consists of the transmission of approximately 30 images per second consisting of 486 visible horizontal lines, each up to 648 pixels.

The video format uses an interlaced mode at 60 areas per second to make better use of bandwidth. This mode is a 4.25 MHz band that converts to a resolution of 30 frames and approximately 270 vertical lines with a total of 525 horizontal lines.

NTSC (National Television Standards Committee) Features

The NTSC format sends out 29.97 frames of interlaced video every second, with a total resolution of 525 lines. It updates the video at 30 frames per second and 60 fields.

To understand NTSC’s challenges, we need to look at its early issues. Initially, black-and-white TVs had to display color signals in black and white, while color TVs had to show signals in color.

Both versions required the same amount of space. The TV tube switched between color and black-and-white pictures. Researchers studied color and black-and-white signals to ensure they worked together. Both types of signals were sent on the same RF carrier.

The brightness signal generated other parts like color, sound, and reference signals. These components recreated the hidden subcarrier with precise timing and size control. The system sends the color signal in two parts, (R-Y) and (B-Y), to produce accurate colors.

The system sent these parts with a 90-degree phase difference, combining them on the same color subcarrier. All of this had to fit into a single 6 MHz channel.

Additionally, the video carrier was 1.25 MHz above the bottom of the channel and 0.25 MHz above the top of the audio carrier, meaning the picture and sound were always 4.5 MHz apart.

The color subcarrier was 3.579545 MHz higher than the picture carrier. TV used sideband transmission for the picture, with the lower sideband being 0.75 MHz wide and the upper sideband 4 MHz wide.

Thus, low video frequencies accompanied high video frequencies. The FM voice carrier was about 75 kHz wide. The system encoded color information on the 3.579545 MHz color subcarrier using amplitude and phase changes.

The color components used a special kind of modulation to ensure everything worked together. The 3.579545 MHz subcarrier also preserved the black-and-white picture. Since the system extracted the color components at the right time, it sent a color change for each line.

This change acted as a signal to maintain synchronization. Occasionally, the color burst level corrected any issues with color strength, like how the sync level maintained video quality.

NTSC Advantage and Disadvantage

NTSC systems work at 60Hz, preventing the classic flickering of the PAL system operating at 50Hz/25FPS, making eyes less tired.

Transmission and interference problems tend to degrade the quality of the picture on the NTSC system. This problem shifts the phase of the color signal, and sometimes, it loses color balance as soon as the frame is captured.

This issue makes it necessary to include a shade control. This is not necessary for PAL or SECAM systems.

Another of its drawbacks is it’s limited to only 525 lines of vertical resolution, which is the lowest of all television systems.

This resolution limit gives a lower-quality image than can be sent on the same bandwidth as other systems.

Digital System

Since the importance of color coding used in devices such as digital televisions, modern video game consoles, and DVDs decreased, there is no longer any difference between systems.

The meaning of NTSC is reduced to a number of lines equal to 480 horizontal lines, with a refresh rate of 29,970 images per second or double per second for interlaced images.

Broadcast System

A television channel broadcasting with the American standard NTSC-M uses 6 MHz bandwidth to contain the video signal, audio signal, and some guard bands.