ADInstruments S7200 Operation Manual page 266

AD INSTRUMENTS
pulse which is part of the baseband video signal. The horizontal sync pulse starts
a horizontal trace. During the horizontal blanking interval, the beam returns to
the left side of the screen and waits for the horizontal sync pulse before tracing
another line. This is called "horizontal retrace" (see graph
When the beam reaches the bottom of the screen, it must return to the top to
begin the next field or frame. This is called the "vertical retrace" and is signaled
by the vertical sync pulse (see graph
takes much longer than one horizontal retrace, so a longer synchronizing interval
– the "vertical blanking interval" – is employed. No information is written on the
video screen during the horizontal or vertical blanking intervals.
Each video standard defines a series of synchronization signals that control how
the video signal is displayed. PAL signals display a video frame 25 times a second
and a frame contains 625 video lines. NTSC signals display a video frame 30 times
a second, but with only 525 lines.
Table: Active Image Value
Video Format
NTSC
PAL/SECAM
The active video image resulting from the scanning always has an aspect ratio
(horizontal/vertical) of 4/3 no matter what the video format is. The color
composite video signal shows that the scanning process requires some additional
room on the left and right sides of each line as well as on the top and bottom of
the active video image region. This additional room includes the synchronization
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S7200 TV Signal Analyzer Operation Manual
Lines/ Active
Frame Lines
525 480/486 29.97 frame/sec 63.55 µs
625 576
c in Figure 7-10 above). The vertical retrace
Frame Rate
25.00 frame/sec 64.00 µs
b in Figure 7-10 above).
Line Active Line
Duration Duration
52.2 µs
52.0 µs