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For the following analyses, equations 9 and 1 0 have been studied to determine whether
the filter response time or the averaging time is the larger, and hence the dominating
parameter for a particular analysis situation.
4.4.1. Optimum Scanning Rate - Logarithmic Sweep
If the filter response time is the dominating parameter, then the dwell time T
0
is set
equal to twice the filter response time T
F:
Using equation 6, and considering Level Recorder paper QP 1143:
21,78
2~
Pf
8
p
82
5,4
f
mm/s
( 11 )
If the necessary averaging time is the dominating factor, then the dwell time is set equal
to twice the averaging time.
AC Recording
For AC recording, we consider the case of equation 1 0:
21,78
2~
Pf
f
p
3,6 8
( 12)
The Level Recorder WRITING SPEED can be calculated from the necessity for the pen to
be able to travel 1 00 mm in one dwell time
w
>
100
To
Using equation 6
w
~
5 Pf
8
A second
limit
on the analysis speed is the maximum Level Recorder WRITING SPEED.
Not only must the Recorder be operated with a stable combination of the LOWER LIMIT-
lNG FREQUENCY and WRITING SPEED, but a low enough WRITING SPEED must be spec-
ified to ensure that the signal ripple is restricted to less than the specified limit of
±0,25 dB.
These considerations can limit the analysis speed and result in a reduction of the previ-
ously calculated PAPER SPEED settings. The above considerations and restrictions have
been taken into account to give Table 4.4 Level Recorder PAPER SPEED and Table 4.5
Level Recorder WRITING SPEED settings for AC recording of deterministic signals. The
required PAPER and WRITING SPEED can be obtained from these tables for the analysis
bandwidth and the maximum analysis frequency.
49
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