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INSTRUCTION MANUAL
LI-3P-1x Series
3-PHASE LINE IMPEDANCE STABILIZATION NETWORKS (LISNs)
SECTI ON 6 -
LISN MEASUREMENTS
1912 1 E l T o ro R d
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Si l vera do, Ca lifo rni a 9 26 76
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(9 49) 459 -96 00
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REV083017
6.1.1 Example
Calculations
An LI-3P-1x Series LISN was used to measure the conducted emissions of
an EUT. The measurement port of the LISN was connected to the RF input
of the measuring instrument via a coaxial cable, through a 10 dB
attenuation pad. A signal is observed on LINE 2, with the LISN under
remote control. The frequency of the signal is 20 MHz, and the measured
amplitude is 40 dBuV. What is the actual amplitude of this signal on the
LINE 2 conductor of the EUT input power?
For the system shown above, there are three (3) correction factors
needed:
1)
The LISN Insertion Loss Factor at 20 MHz for LINE 2 in remote mode
2)
The insertion loss value of the 10 dB attenuator at 20 MHz
3)
The insertion loss value of the coaxial cable at 20 MHz
We’ll assume that the insertion loss of the
coaxial cable
at
20 MHz
is
2 dB
,
and the insertion loss of the
10 dB attenuator
at
20 MHz
is
10 dB
. And, by
referring to the typical insertion loss table shown in Figure 10, the
LISN
insertion loss
factor
for
LINE 2
in
remote mode
is
0.5 dB
(in practice, you will
use your actual calibrated factors rather than the typical factors)
.
Measured amplitude @ 20 MHz =
40.0 dBuV
LISN Insertion Loss Factor @ 20 MHz for LINE 2
in remote mode =
0.5 dB
Insertion Loss of 10 dB Attenuator @ 20 MHz =
10.0 dB
Insertion Loss of Coaxial Cable @ 20 MHz =
2.0 dB
Measured Amp Insertion Losses
= Corrected Reading =
52.5 dB
μ
V
