Reading The VLM-40 – 7
Fig.6. A single horizontal scan line
(75% full-field color bar signal) as
seen on a waveform monitor.
H
OW
T
O
R
EAD
T
HE
VLM-40...
VLM-40 NTSC T
ECHNICAL
I
NSTRUCTION
M
ANUAL
OPERATION
The VLM-40 measures a NTSC Composite signal and displays
its sync, average luminance, and peak luminance levels across a
40-segment bar graph.
NOTE: The VLM-40 is set at the factory to measure active picture
lines occurring after 21 lines of vertical blanking. For PAL/SECAM
measurements, contact the the factory for information on the
VLM-40 PAL/SECAM meter.
1. Using a standard television test signal generator, feed a 75%
full-field NTSC color bar signal with standard setup at 115
IRE p-p to the VLM-40. Set the filter to low-pass to attenuate
the chroma signal from the waveform display.
2. Study and compare the VLM-40 and waveform monitor
illustrations shown in Fig. 7 on the next page.
IRE Units
120
100
80
60
40
20
-20
-40
0
setup =7.5
63.5 µs
2.5 µs
color bars
luminance
color
burst
sync
