History of NTSC

	Revision 6 . . November 5, 2001 5:24 am by The Anome [*remarks re nominal frequency...]
	Revision 5 . . September 28, 2001 10:31 am by Simon J Kissane [*added mention of tone control on NTSC sets]

---

Difference (from prior major revision) (no other diffs)

Changed: 3c3

NTSC format consists of approximately 30 interlaced? frames of video a second, each consisting of 525 lines of vertical resolution. NTSC interlaces its scanlines, drawing odd-numbered scanlines in odd-numbered fields and even-numbered scanlines in even-numbered fields, which gives a nearly flicker-free image at 59.94 Hertz refresh frequency, which is close to the 60 Hz [alternating current]? power used in the United States. (Compare this to the 50 Hz refresh rate of the 625-line PAL video format used in Europe, where 50 Hz (25 Hertz is resonant) AC is the standard; PAL has noticeably more flicker than NTSC.) Synchronization of the refresh rate to the power cycle helped [motion picture]? film cameras record early live television broadcasts, as it was very simple to sync a film projector to capture a frame of video to a film cell using the frequency of the alternating current. Also, it was preferable to match the screen refresh rate to the power source so as to avoid wave interference that would produce rolling bars on the screen.

NTSC format consists of approximately 30 interlaced? frames of video a second, each consisting of 525 lines of vertical resolution. NTSC interlaces its scanlines, drawing odd-numbered scanlines in odd-numbered fields and even-numbered scanlines in even-numbered fields, which gives a nearly flicker-free image at approximately 59.94 Hertz (nominally 60 Hz / 1.001) refresh frequency, which is close to the 60 Hz [alternating current]? power used in the United States. (Compare this to the 50 Hz refresh rate of the 625-line PAL video format used in Europe, where 50 Hz (25 Hertz is resonant) AC is the standard; PAL has noticeably more flicker than NTSC.) Synchronization of the refresh rate to the power cycle helped [motion picture]? film cameras record early live television broadcasts, as it was very simple to sync a film projector to capture a frame of video to a film cell using the frequency of the alternating current. Also, it was preferable to match the screen refresh rate to the power source so as to avoid wave interference that would produce rolling bars on the screen.