Preparation of Equipment and Controls
Power/Weighting Switch
This is a three-position switch labelled OFF-A-LIN. In the OFF po-
sition all power is removed from the instrument. The ‘A’ position
allows sound levels to be measured with ‘A’ weighting, (see figure
1). For a linear or ‘flat’ frequency response the LIN is used.
Figure 1 – ‘A’ weighting curve
Battery Check Button
A push button labelled BATT is provided to allow periodic check-
ing of the battery condition. A meter deflection in the area marked
‘BATT’ shows the batteries are in good condition.
'A' AND LINEAR FREQUENCY WEIGHTINGS
-80
-70
-60
-50
-40
-30
-20
-10
0
10
10
100
1K
10K
Frequency/ Hz
SPL/d
B
' A' Weighting
Linear
7
Summary of Contents for GA112
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