Color-Bar Generator

a device for producing television test signals that create an image on the screen of a color kinescope (receiver picture tube) in the form of colored and colorless bars. A common type produces eight vertical bars of equal width and height on the screen: white, yellow, cyan, green, red, magenta, blue, and black. The brightness of a bar decreases from left to right.

At the output of a color-bar generator three video signals of rectangular waveform are produced, with repetition rates for the green, red, and blue colors equal to f_line, 2f_line, and 4f_line, respectively, where f_line is the horizontal scanning frequency. The signals are fed to the input of a display monitor or decoder in order to obtain the composite signal of the color bars; when a decoder is used, the three color-difference signals obtained after decoding are used to monitor and adjust the decoder by means of an oscilloscope. The composite signal is also used to monitor distortion created by video tape recorders, transmitting television stations, and communications lines. Individual types of distortion can be monitored visually from an image of the color bars on the screen of the kinescope. The image, in the form of vertical color bars of specific height, is included in general-purpose television test patterns.