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POTS Testing and Fault Location
4
The POTS Toolbox
Power Harmonics Test
The Power Harmonics test, available as a softkey test option on the VF Noise
test result screen, shows values of both odd and even power frequency
harmonics in the voice frequency band. After running the VF Noise test, press
) to obtain a snapshot graph of all power frequency
C(
Power Harmonics
harmonics on the line. The test is made from Tip and Ring to Ground, with no
filter applied. There are no setups required for this test, and the fundamental
frequency (50 / 60 Hz) is automatically derived from the selected Language /
Country in
.
USER OPTIONS
Figure 4-25 illustrates a typical set of Power Harmonics on a working POTS
pair with a normal degree of harmonics, due to inductive power line coupling.
acy99s.eps
Figure 4-25. Power Harmonics Test Results
Note that the fundamental coupling frequency (60 Hz) is the largest signal
present, as is normally the case when electromagnetic fields around power
lines couple inductively into the telephone cable. With normal inductive
rd
th
th
coupling, the odd harmonics (3
, 5
, 7
, etc.) are predominant, and have
exponentially decreasing levels as shown in Figure 4-25.
4-43
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