BRUEL & KJAER Mediator 2238, Руководство по обслуживанию, Страница: 20 / 34

Chapter 2 — Checking Procedure
Checking Procedure
2238 Mediator Integrating Sound Level Meter
Service Manual
Brüel & Kjær
14
Table 2.4 C-Weighted (LCFP)
2.3.4 Overload
Testing is done in the Basic SLM mode, as the overload feature uses the same elec-
tronics and hardware under both Basic and Enhanced SLM configurations.
Action:
●
Press , select
Application
, then
Basic SLM
. Press , select
Weightings
.
Use to set Detector 1’s
Freq. Wgt.
to C, and Detector 2’s
Weighting
to
Peak/C
. Use to select
OK
, then select
General
. Set range to
50 - 130 dB
.
Use to select
OK
, then to
Close
.
●
Set generator output to 2.0 V (126 dBµV), 20 Hz.
Result:
●
No overload indicated. Display reads
»
123.8 dB (RMS).
Action:
●
Increase Generator output by 1.5 dB.
Result:
●
An overload is indicated in the display window with .
●
Display reads
»
125.2 dB (RMS).
2.3.5 Measuring Range – Attenuator Accuracy
Action:
●
Set the 2238 Detector 1 to RMS,
BB/F
and
C
weighting. Set the range (you can do
this anytime directly by pressing ) to
50.0 - 130.0 dB
. Press to
OK
. Set
the generator output to 1 kHz, and adjust the generator amplitude until the dis-
Generator Freq.
Hz
dB SPL value
on the Display
Actual
Reading
Ref 1000 128.0 128.0
10 113.7 + 1.0/ – 3.0
31.6
125.0
±
0.5
3981
127.2
±
0.4
19950 116.8 + 1.0/ – 3.0