User's Manual

79
CHAPTER 5: Measurements
• A reversed number indicates a split pair.
• A straight line between pairs indicates a good pair.
• No line between wire pairs indicates an open.
• An X between wire pairs indicates a reversed pair.
• A | between wire pairs indicates a short.
• The measured length of the pairs 1-2, 3-6, 4-5, and 7-8 are shown on the left
side.
In the example, OMNIScanner displays split pairs on 1 - 2 and 4 - 5 although
they are wired straight through, a reversed pair 3 - 6, an open on wire 7, and a
short on wire 8 to the Shield.
Press ESC to exit the WIREMAP screen.
5.3.2 L ENGTH /D ELAY
The Length/Delay function measures a cable’s length, propagation delay, and
skew. OMNIScanner will determine whether the cable is open or shorted.
The accuracy of the NVP (Nominal Velocity of Propagation) setting determines
the exactness of length measurements. The NVP specified by cable manufacturers
is used for all the cables in OMNIScanner’s library. When creating or editing
cables, the NVP value can be customized. (See Section 3.5, Setup: Cables, for
further information.)
Delay is a measure of the time required for a signal to travel from one end of
the circuit to the other. OMNIScanner measures the delay from when the pulse
was sent and when the reflection was received. Knowing the speed that the pulse
1