Specifications

The term, Lines of Definition actually refers to the number of times the
picture screen can be modulated (made lighter and darker)
across the screen.
Therefore a test pattern for this purpose would display
vertical lines on the screen
of the Monitor. Fifty white lines alternating with fifty black vertical lines across the
screen would constitute a total of 100 Lines of Definition. The more lines that can
be discerned, the greater the fine detail observable in the picture.
High picture definition would enable a viewer to clearly see as many as 500 or
more "Lines" in each screen width. Medium definition would blur 500 "Lines" but
would clearly show 400 or less "Lines". Low picture definition would blur 300 or
more lines, but clearly identify 200 or fewer "Lines" per screen width. To clearly
identify the picture definition capacity of any specific CCTV system, a test pattern
generator needs to be connected at the Camera location and the resulting test
pattern observed at the Monitor location.
The VLTG-800 is a
Video Line Test Generator that creates a normal NTSC
video picture with a test pattern consisting of 100, 200, 300, 400, 500, 600, 700,
and 800 "Line" groups. Each of these groups of "Lines" is clearly identified so that
you do not have to count the lines on the screen. Monitors may be tested "on the
bench" by connecting the VLTG-800 directly to the Monitor under test.
The "Lines of Definition" for that Monitor will be clearly evident on the
Monitor screen. This test should be performed prior to any field tests of the CCTV
system to make sure that the Monitor does not constitute the limiting factor in
overall picture definition.
The ability of a Video Recorder to reproduce a picture without degrading
picture quality can also be tested with the VLTG-800 by connecting it to the
Recorder and Monitor, recording the test pattern and playing it back into the
Monitor. There should be no reduction in the "Lines" as played back into the
Monitor.
CCTV TRAINING MANUAL PAGE 22 OF 28