17
Fig. 3.17. Calibration – setting reference level.
Fig. 3.18. Calibration – measurement in progress.
Fig. 3.19. Calibration – accept the result.
Fig. 3.20. Calibration – error message.
accept the result of the calibration / zero calibration factor, if calibration error,
start / repeat the measure,
set reference level – increase by 0.01dB,
hold down 1.5 second – automatic repeat,
set reference level – decrease by 0.01dB,
hold down 1.5 second – automatic repeat,
abort calibration procedure, reject results and back to the results screen.
4. RECOMENDATIONS FOR INSTRUMENT USE
During instrument use following recommendations should be strictly observed:
•
perform all connection changes (connecting or disconnecting of microphone) only when
the instrument is turned off; making these changes when the instrument is turned on
can lead to instrument damage,
•
protect the microphone against mechanical shocks, dust, moisture and strong gusts of
wind (use windscreen!).
4.1. Recommendations for correct performing of measurements
Fasten the instrument (or its microphone) to its supporting stand and ensure you are located at
a distance (from the instrument or its microphone) assuring to avoid sound field disturbance.
The measurement range should be chosen so that the meter does not indicate over-range or
under-range condition of the measurement circuit. If the indicated value is less than the lower
limit of the meter's linearity range the correction should be subtracted from the measurement
result. This correction is calculated on the basis of the self-generated noise level read from
calibration certificate using the formula::
(
)
Ls
Lw
L
⋅
⋅
−
⋅
=
1
.
0
1
.
0
10
10
log
10
where:
L
corrected sound level
Lw
sound level read from the meter
Ls
self-generated noise level
