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52
AC Recording
For AC recording, we consider the case of equation 1 0.
1 5 · 1
o-
3
.!!
2 .
1.
I
p
f
i.e.,
p
~
1
1
25 · 10-3 Bf
( 1 5)
Imposing a restriction that the Level Recorder WRITING SPEED must permit the pen to
travel 1 00 mm in one dwell time, we have the third condition that
w
~
100
To
i.e.,
w
~
p
1
33.
104-
I
B
If we also apply the practical limits of Level Recorder stability and account for the maxi-
mum control settings, we can draw up Table 4.8 for AC recording of linear sweeps with
"x
1 Lin" FREQUENCY SCALE. If any other FREQUENCY SCALE is selected, then we
must amend equations
14
and
1
5 by an appropriate factor of
10
and recalculate PAPER
SPEEDS.
In practice, it is found that there is a lower limit to the frequency range for reliable analy-
sis with these settings. See section 4. 7 for details.
Bandwidth
WRITING SPEED
PAPER SPEED
(Hz)
(mm/s)
(mm/s)
3,16
50
0101
10
125
0,1
31,6
500
1,0
100
500
3,0
316
500
10,0
. 1000
125
10,0
140197
Table 4.8. Level Recorder settings for AC Recording of Deterministic
Signals with FREQUENCY SCALE
"x
1 Lin.,
DC Recording
For DC Recording:
B
15 · 1o-3 -
I
p
p
2TAV
B
3175
·1o-3-
TAV
(16)
The critical paper speed can be found from equations
14
and
16
having determined the
averaging time required from equation 9. This averaging time is the largest AVERAGING
TIME which is less than the filter response time. WRITING SPEED on the Level Recorder
should be set as fast as possible without introducing instability.
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