he blanking pulses. When discussing synchronization and blanking, we often refer to certain time intervals. These are described as follows: The time at the horizontal blanking pulse, 2-5 in Figure 16.3, is called the horizontal synchronizing interval. The interval 2-3 in Figure 16.3 is called the front porch. The interval 4-5 is the back porch. The intervals are important because they provide isolation for overshoots of video at the end of scanning lines. Figure 16.4 illustrates the horizontal synchronizing pulses and corresponding porches. The vertical scanning generator in the video/TV receiver is synchronized with the cam- era (transmitter) synchronizing generator at the end of each field by means of vertical synchronizing pulses. The time interval between successive fields is called the vertical 0.25 us Video ~ 30% of of max sync range Back porch Setup video signal Front porch Ultra black 1.25 us 3.8 us Horizontal interval Horizontal pulse Figure 16.4 Sync pulses and porches. 16.4 CRITICAL VIDEO PARAMETERS interval. The vertical synchronizing pulse is built up during this interval. The scanning generators are fed by differentiation circuits. Differentiation for the horizontal scan has a relatively short time constant (RC) and that for the vertical a comparatively long time constant. Thus the long-duration vertical synchronization may be separated from the comparatively short-duration horizontal synchronization. This method of separation of synchronization, known as waveform separation, is standard in North America. In the composite video signal (North American standards) the horizontal synchroniza- tion has a repetition rate of 15,750 frames per second, and the vertical synchronization has a repetition rate of 60 frames per second (Refs. 2, 3). 16.4 CRITICAL VIDEO PARAMETERS 16.4.1 General Raw video baseband transmission requires excellent frequency response-in particular, from dc to 15 kHz and extending to 4.2 MHz for North American systems and to 5 MHz for European systems. Equalization is extremely importa