10
. If
it
is necessary
to
change the
start
frequency,
the
paper
must
be moved an
equiva-
lent
amount
on
the
sprocket to ensure
that
correct
synchronization
is
maintained.
3.3.5.
Analysis
with
variable
averaging
time
using
an
X-V
Recorder
In
this
measurement
mode,
which
is possible
when
a
Measuring
Amplifier
Type
2607
(or equivalent) is employed, band
switching,
pen
positioning
along
the
X (= frequency)
axis, and
Amplifier
averaging times are all controlled by
the
built-in
program
in
the
Band
Pass Filter.
AO 0034
'X'
'y '
r -
--
---
--
--
-----
,.:-----,
Me
asuring
Amplifi
er AO 0145 I
Band
Pas
s F
ilt
er 1617
l
i
~
~
.
~:)
1
~
-
.
-
• .
~--:
:
.
1
IJ
I
2607
'"
L r
~
' AO 0014/
AO
0064
X- Y
Rec
order
AO 0064
710365
Fig
. 3. 11 .
Instrumentation
using
X-Y Recorder
and
Type
2607
to
plot
spectrograms
with
variable
averaging
time
1. Connect
the
instrumentation
as
shown
in Fig .3.11 .
Note
that
program
control
of
averaging
times
in
the
Type
2607
is
only
possible
when
a
ground
connection exists
with
the
Type
1617
. This
is
automatically
achieved
when
the
Filter
input and
output
cables are
connected
to
the
Amplifier
. Ex-
ternal
and
internal
connections to the AVERAGING TIME CONTROL socket are
shown
in Fig .3.7 and Fig .3.B respectively.
2.
Adjust
the
Measuring
Amplifier
as described in
section
3 .3 .1/ 2
with
the
following
additions:
METER FUNCTION
AVERAGING TIME
(front
panel)
AVERAGING TIME
(rear panel)
"Log
"
"300
seconds"
"Remote"
3.
Adjust
the
Band Pass Filter as described in
section
3 .3 .1/ 3
with
the
following
changes:
AVERAGING CONTROL, Program
and
Min
. Time
switches
Select a program
to
suit
the
measuring
problem.
See section 4.2 .2
for
further
information
.
4 .
Make
preliminary
checks and
adjustments
to
the
X-V Recorder as recommended
in
its
Instruction
Manual
.
5. The
DC
ramp
output
from
the Type
1617
that
controls
the
deflection
of
the
Recorder
pen in
the
X (= frequency) direction is always 0 V
at
the
start
frequency,
increasing
with
a rate
of
0,20B
V per 1/ 3-octave band. To
assist
in
setting
up the
X-axis
a
ref-
erence signal
of
6,24
V (equivalent
to
three
decades)
is
available
from
the
ramp
out-
put
when
the
left-hand
FILTER
CONTROL MODE
switch
is
put
in
position
"Manual"
.
27
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