Fluke CableAnalyzer DSP-4000 Series, User Manual

Page: 125 / 228

Calibrations and Custom Test Standards
NVP Calibration
6
6-3
NVP Calibration
The Determine Cable NVP function allows you to determine the NVP (nominal
velocity of propagation) for a known length of cable and save the value for
additional measurements of unknown lengths of the same type of cable. The
calibrated NVP value applies only to the selected test standard. You can also enter
a known NVP value or use the
Set to Default
softkey to set the NVP to
the default value, which is the NVP for a typical sample of the selected cable type.
To determine a cable’s NVP value, proceed as follows:
Notes
To determine a cable’s NVP, you should use a cable at least 15 m
(50 ft) long. The recommended length is 30 m (100 ft).
NVP is determined for the cable pair with the shortest electrical
delay.
1. Attach a channel link interface interface adapter to the main unit.
2. Turn the rotary switch to SPECIAL FUNCTIONS.
3. Use
D
to highlight
Determine Cable NVP
.
4. Press
E
.
5. As prompted by the display, connect a known length of the appropriate cable
to the test tool. Use the RJ45 to BNC adapter, if necessary.
6. Verify that no cables are connected to the DB9 connector on the test tool.
7. Press
T
.
8. Use
D
or
U
to change the displayed length to the known length of the
attached cable. As you adjust the length measurement, the NVP value changes
automatically. The range for NVP values is 50.0 % to 99.9 %.
9. When the displayed length matches the known length of the cable, press
S
to store the new NVP value and return to the main Special Functions
menu. To exit the screen without saving the new NVP value, press
e
.
If the message
CABLE FAULT DETECTED
appears, verify that the selected
cable type is correct, check the cable for proper pin connections, or calibrate with a
different cable.