The precise frequency was chosen so that horizontal line-rate modulation components of the chrominance signal would fall exactly in between the horizontal line-rate modulation components of the luminance signal, thereby enabling the chrominance signal to be filtered out of the luminance signal with minor degradation of the luminance signal.
22.
The precise frequency was chosen so that horizontal line-rate modulation components of the chrominance signal would fall exactly in between the horizontal line-rate modulation components of the luminance signal, thereby enabling the chrominance signal to be filtered out of the luminance signal with minor degradation of the luminance signal.
23.
Early colour television studio cameras consisted of four tubes to relay the picture : three were receptive to colour ( red, green and blue the chrominance signal ) with the fourth providing a high-resolution monochrome image ( the luminance signal ) which was still required as many viewers still watched on monochrome receivers.
24.
During the 1970s, various off-air NTSC video-recordings were made by American and Canadian " Doctor Who " fans, which were later returned to the BBC . Whilst the quality of these early domestic video recordings was not suitable for broadcast, the lower-definition chrominance signal could be retrieved from them.
25.
At certain times, the chrominance signal represents only the U signal, and 70 nanoseconds ( NTSC ) later, the chrominance signal represents only the V signal . ( This is the nature of the quadrature amplitude modulation process that created the chrominance signal . ) About 70 nanoseconds later still,-U, and another 70 nanoseconds,-V.
26.
At certain times, the chrominance signal represents only the U signal, and 70 nanoseconds ( NTSC ) later, the chrominance signal represents only the V signal . ( This is the nature of the quadrature amplitude modulation process that created the chrominance signal . ) About 70 nanoseconds later still,-U, and another 70 nanoseconds,-V.
27.
At certain times, the chrominance signal represents only the U signal, and 70 nanoseconds ( NTSC ) later, the chrominance signal represents only the V signal . ( This is the nature of the quadrature amplitude modulation process that created the chrominance signal . ) About 70 nanoseconds later still,-U, and another 70 nanoseconds,-V.
28.
However, no comb filter can totally eliminate NTSC artifacts and the only complete solutions to dot crawl are not to use NTSC or PAL composite video, maintaining the signals separately by using S-Video or component video connections instead, or encoding the chrominance signal differently as in SECAM or any modern digital video standard as long as the source video has never been processed using any video system vulnerable to dot crawl.
29.
To provide sufficient bandwidth for the chrominance signal, yet interfere only with the highest-frequency ( and thus least perceptible ) portions of the luminance signal, a chrominance subcarrier near 3.6 MHz was desirable . 227.5 = 455 / 2 times the line rate was close to the right number, and 455's small factors ( 5 ?7 ?13 ) make a divider easy to construct.
