2 – Description
The VLM-40 features a single 40-segment bar graph, as shown
in Fig. 1. Peak and average luminance are simultaneously
displayed on 30 LED segments over a range of 0 to 120 IRE
units (for a resolution of 4 IRE units). Average luminance levels
are indicated as a continuous bar, while peak levels are
displayed as a single LED above the bar. Luminance levels in
the 0 to 100 IRE range are displayed as green LED segments.
Levels over 100 IRE use red indicators for increased recognition.
Sync is displayed on one of ten yellow LED segments on an
expanded scale ranging from -52 to -30 IRE units (for a
resolution of 2 IRE units). A green LED indicates a proper sync
level of -40 IRE.
The front meter panel also includes sync and setup LEDs that
detect the status of these corresponding video levels. Under
normal operating conditions, the sync LED will be green
whenever the video source has a proper sync signal. If sync
drops out, the sync LED will flash red for single sync drop-outs
greater than 2 H, or stay on full for continuous drop-outs.
The setup LED is green whenever the video source has a Setup
level greater than 7.5 IRE units, and red when setup goes below
4 IRE. The examples in the
Operation
chapter (starting on
page 6) will explain how to use all these features in more detail.
S
IMULTANEOUS
P
EAK
A
ND
A
VERAGE
D
ISPLAY
...
Fig. 1. The VLM-40’s 40-segment
bar graph displays sync, average,
and peak luminance video levels.
S
YNC
A
ND
S
ETUP
V
IOLATION
LED
S
...
VLM-40 NTSC T
ECHNICAL
I
NSTRUCTION
M
ANUAL
DESCRIPTION
COMPOSITE VIDEO LUMINANCE METER
MODEL VLM-40
-48
-40
0
20
40
60
80
100
120
© 1990
SYNC
LUMINANCE
IRE UNITS
-32
SYNC
SETUP
