How PAL video standard works?
The PAL system specifies 625 individual horizontal scan lines. Here's how it works:
1. The scanning beam scanning every other horizontal line, from the top of the image to the bottom, which equals one field.
2. The beam completes one line at 15,625Hz. That's 15,625 cycles per second! This is the horizontal scan rate.
3. The beam shuts off at the end of the first field.
4. Back at the top, the beam fills in the other half of the lines- the even numbered lines.
5. Two fields are scanned for every frame.
6. PAL has a field rate of fifty fields per second.
7. The two fields are displayed in immediate succession, creating the appearance of a single 625-line frame.
8. PAL can complete 25 frames per second to provide compatibility with the European electrical supply frequency (50Hz).
9. Color, for PAL video, is carried at 4.43 MHz.
10. Sound for PAL video varies with the version used.