Examples – 11
VLM-40 NTSC T
ECHNICAL
I
NSTRUCTION
M
ANUAL
OPERATION
The following examples illustrate how you can use the VLM-40
to identify common problems that may occur in an NTSC
composite video signal.
E
XAMPLE
VLM-40
R
EADINGS
...
M
ISSING
S
YNC
P
ULSES
L
OW
S
YNC
L
EVEL
COMPOSITE VIDEO LUMINANCE METER
MODEL VLM-40
-48
-40
0
20
40
60
80
100
120
© 1990
SYNC
LUMINANCE
IRE UNITS
-32
SYNC
SETUP
IRE Units
100
80
60
40
20
-20
-40
0
setup = 7.5
Fig. 12. On the VLM-40, the sync LED flashes red each time a sync
pulse is missing. You may not easily detect this fault using a
waveform monitor. NOTE: With a complete loss of sync, the meter
will not operate.
COMPOSITE VIDEO LUMINANCE METER
MODEL VLM-40
-48
-40
0
20
40
60
80
100
120
© 1990
SYNC
LUMINANCE
IRE UNITS
-32
SYNC
SETUP
IRE Units
100
80
60
40
20
-20
-40
0
setup = 7.5
Fig. 13. On the VLM-40, the sync LED is red. Sync bar graph has no
lit segments. The waveform monitor shows no sync pulse.
