Colorburst is a signal used to keep the chrominance subcarrier synchronized in a color television signal. By synchronizing an oscillator with the colorburst at the beginning of each scan line, a television receiver is able to restore the suppressed carrier of the chrominance signals, and in turn decode the color information.
In NTSC, its frequency is 39375/11 kHz or 3579545 Hz, whereas PAL uses a frequency of 4.19 MHz. SECAM is unique in not having a colorburst signal, since the chrominance signals are encoded using FM rather than QAM, making synchronization irrelevant.
Since the colorburst signal has a known amplitude, it is sometimes used as a reference level when compensating for amplitude variations in the overall signal.
Because color televisions are so common, so are colorburst crystals, and they are used in various other applications. For instance, the time-of-day clock in a PC often runs at four times the colorburst frequency.
20, in a conventional color killer circuit 1, a colorburst signal and a sub-carrier signal are inputted to a multiplier 2, whereby an output according to the presence or absence of the colorburst signal is applied to an LPF 3, and thus, a voltage signal V1 as shown in FIG.
In the embodiment shown, the phases of the colorburst signal and the sub-carrier signal which are to be inputted to the multiplier 12 in receiving the color television signal are locked in a manner that the both become to be anti-phase.
The signal is separated into the carrier color signal and the colorburst signal by the bandpass amplifier 144, and the colorburst signal is amplified by a burst amplifier 146 to be applied to the color killer circuit 10, the ACC circuit 100 and the APC circuit 120.
By synchronizing an oscillator with the colorburst at the beginning of each scan line, a television receiver is able to restore the suppressed carrier of the chrominance signals, and in turn decode the color information.
In NTSC, its frequency is 39375/11 k Hz or 3579545 Hz, whereas PAL uses a frequency of 4.19 MHz.
Because color televisions are so common, so are colorburst crystals, and they are used in various other applications.
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