VERTICAL SCANNING FREQUENCY

The original vertical scanning rate for black and white was tied to the power line frequency, 60 Hz. It takes two 60 Hz fields to make a complete picture. The horizontal scan rate was derived by counting up from 60 Hz, (30 pictures per second x 525lines per picture). In the color system the vertical rate is derived from the horizontal, which is derived from the color subcarrier. The formula is (Horizontal Rate x 2/525 = Vertical Rate) or backing all the way up o the subcarrier it's (3,579,545 Hz)(2/455)(2/525) = 59.94 Hz.