Introduction – 1
E
ASY
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O
-U
SE
V
IDEO
L
EVEL
M
ETER
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S
IMULTANEOUS
D
ISPLAY
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P
EAK
A
ND
A
VERAGE
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S
PECIFICATIONS
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The DORROUGH Composite Video Luminance Meter, Model
VLM-40, is a simple, easy-to-use, video level meter designed
for quick dynamic measurements of video levels from any
connected NTSC source (e.g., camera, VTR, etc.).
Using a single 40-segment bar graph, the VLM-40
simultaneously displays three amplitude parameters of the
composite video signal: sync, average luminance, and peak
luminance. Two additional indicators detect the presence of
proper sync and setup levels.
Just like a traditional waveform monitor, the VLM-40’s peak-to-
average features enable you to quickly check lighting
conditions, contrast, drop-outs, sync stability, and video signal
quality. However, you’ll find it easier to use as you interpret
data on the single meter scale. The VLM-40 is insensitive to
chroma information, VITS (vertical interval test signals), and it
responds to luminance signals as short as 200 ns in length.
• INPUT IMPEDANCE
25 k
Ω
unterminated, 75
Ω
terminated
• SYNC RANGE
-50 to -32 IRE units
• LUMINANCE RANGE
0 to 120 IRE units
• SYNC AND LUMINANCE FREQUENCY RESPONSE
Exceeds IRE frequency response
• MINIMUM PULSE WIDTH RESPONSE
200 ns
• METER RESOLUTION
Luminance scale is 4 IRE units; Sync scale is 2 IRE units
• DIMENSIONS
8
1
⁄
4
"W x 2
7
⁄
8
"H x 6
1
⁄
2
" D
DORROUGH Electronics constantly strives to meet or exceed the highest
professional standards. As a result of these efforts, modifications may be made
from time to time to existing products without prior notice. Specifications
and appearance may differ from those listed or shown in this manual.
© DORROUGH Electronics, 1994
DORROUGH Electronics
5221 Collier Place
Woodland Hills, CA 91364 USA
Voice: 818•998•2824 – FAX: 818•998•1507
VLM-40 NTSC T
ECHNICAL
I
NSTRUCTION
M
ANUAL
INTRODUCTION
