| 摘要 |
A color subcarrier generator for PAL uses a one-quarter horizontal frequency signal from a sync generator to sample the subcarrier signal. The sampled signal is phase and frequency compared with a 25 Hz (one-half vertical frequency) signal from the same sync generator to control the frequency of the subcarrier signal. Thus the required 25 Hz PAL offset is obtained. The one-quarter horizontal frequency sampling signal can also be used in NTSC and SECAM subcarrier generators.
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