Extech Instruments 407790A, User Manual

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407790A-EN_V2.4 1/20
4.2 SEL, Leq, Lmax, Lmin, LN Measurements
1. Power on the meter. After the power-on screen displays, the SLM measurement screen
appears.
2. Use the FREQ WEIGHT TIME button to select the frequency weighting characteristic. For
normal sound level measurements, select the “A” setting.
When “C” (C-Weighting) is selected, the equivalent continuous sound pressure level (LCeq) is
measured.
3. Use the FREQ WEIGHT TIME button to select the time weighting characteristic. For normal
sound level measurements, select the “F” (Fast) setting.
(This setting does not affect a measurement result of continuous sound level mode.)
Note: The meter performs high-speed sampling of the sound pressure waveform to determine
Leq and SEL. It is not affected by the time weighting characteristics.
4. Use the

LEVEL

buttons to set the level range. The main channel bar graph indicator should be
in the middle of the range.
If the “ OV ” or “ UN ” indicators appear, change the level range setting.
5. Set the measurement time from the menu. Press the MENU button to enter the menu list
screen.
6. Use the

+
/

-
buttons to select “A). Measurement Time” then press

button.
7. Use the

+
/

-
and

buttons to set the desired measurement time from 1s to 23h 59m
59s.