28
Fig.
4.8.
Sound Level
Meter
with Filter Set Type 1625
The Filter Set Type 1624 has 10
active
octave
band
filters
with
centre frequencies
from
31,5 Hz
to
16 kHz and a
"Lin."
position.
Analysis can be
plotted
by hand
or
more
conveniently
semi-automatically
with
Level
Recorder
Type 2317
or
2309.
Use
of
the Filter Set Type 1625
permits
octave
and 1f3
octave
frequency analysis
with
either
octave
or
1f3
octave
frequency steps. The centre frequencies
for
the
octave
or
1
/3
octave
filters
are
from
20
Hz
to
20 kHz. The Type 1625 has
31
active
overlapping
octave
filters
and
31
active
1f3
octave
filters and a
"Lin
."
position.
Analysis can be hand
plotted
or
recorded
using Level Recorder 2317
or
2309. The recording is fully
automatic
and
optimised
to
obtain
an accurate recording in a
minimum
time. The centre frequency
of
the
filter
used is indicated
on
the
display
of
the filter.
When
a Filter Set is
plugged
into
the
socket
at
the
b
ottom
of
the Sound Level
Meter,
the
batteries
from
the Filter Set
are
used as a
back-up
power
supply
for
the
Sound
Level
Meter.
This can
double
the
measurement
life
of
the Sound Level
Meter
(if
the
Filter
Set
is
not
used). The
Filter
Set
is
only
powered
when
the
EXT. FILTER
switch
on
the
Sound
Level
Meter
is set
to
"In".
Use
of
Filter
Sets
Types
1624 and 1625
for
frequency
analysis
with
the
Type
2230 is
fully
described
in the
Instruction
Manuals
for
the
Filter
SPt~
OODDOODOODODDDDODDDDD
D
DDDODDDDDDDDDDDDDDDDDDDDDDD
D
Briiet
& Kjaer
Recording
Mode
:
DC
l
in
.
~
DC
log
. D AC
Log
.
c::::J
AC A
ve
raging _ _ R
ange
: _
(dB)
Paper
Speed
:~
mm
/s
Wr
.
Speed
:
~mm/s
Rec.
No
.:_
dB
oate
:
__
10
Ttme
Sign
.:
__
Zero
leve
l
:
~
0
M~~~
i
~eobj
.:_
10
1/3
octave
anal
ysis
20
wi
th
1625
arid2317 -
30
--f-
_ )
-
Start
Lone
Octave-
~
31
,5
Hz
63
125
250
500
1 k Hz 2 4 8
16
lin
QP
0 1 5 1 Start
line
113
Octave
20 25
40
50
80
100
160
200
315
400
630
800
1,
25
1.6
2.5
3,15 5 6 .3 10 12.5
20
]25
3.15
40
Lm
1613/16 1
83032112
Fig. 4.9. Third octave analysis recording with Filter Set Type 1625
and
Level Recorder Type 2317
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