Fluke 990DSL, Руководство пользователя

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POTS Testing and Fault Location
The POTS Toolbox
4
4-43
Metallic coupling due to power line crosses will exhibit a high fundamental
content, but will have little or no harmonic frequency content.
Coupling due to AC current in the cable sheath, caused primarily by large
earth return currents from unbalanced 3-phase power lines , will exhibit high
fundamental content as well as both odd and even harmonics.
Press
A
(
Continuous Harmonics
) to view changing harmonics in real-time.
VF Loss Test
The VF Loss test requires that a manually-controlled VF transmitting device
(such as another CopperPro tester or the C9925BLT) be connected at the far
end of the pair. The device must be capable of transmitting single tones at a
level of 0 dBm at 600
Ω
. The CopperPro tester measures the signal level at the
near end and translates it into dB of insertion loss, assuming a 0 dBm transmit
level.
Setting Up a VF Loss Test
To set up a VF Loss test, select the test in the POTS Toolbox and then press
D
(
Setups
). Follow the instructions under “Displaying a Setup Menu” in
Chapter 3. Table 4-8 describes the setup parameters for the test.
Table 4-8. VF Loss Setup Parameter
Parameter Settings (default in bold)
Termination Impedance 600
Ω
or 900
Ω
Loss Pass Thresh., 1004 Hz < 10.0 dB (Range = 0.0 to 49.9 dB)