LanTEK® II Series Manual

Chapter 6

Structured cabling testing

6.13. Impedance Test

The average impedance is calculated from delay of electrical signal and capacitance measurement. The result is indicated in ohm. The average impedance can help in indentifying damages to cable, connections or cable sections with impedance mismatch.

Since this test uses a capacity measurement, the correct cable type must be indicated to obtain a precise measuring result.

NOTE:

The measurements are incorrectly calculated if the setting is for a type CAT 3 cable (the cable insulation containing PVC), but the test is actually performed on a CAT 5 cable

(insulation containing Teflon®). Therefore, ensure that the correct cable type is selected.

Illustration 6.13. Impedance Test

6.13.1. Impedance Error

Impedance errors cause signal reflections and signal reduction. Average impedance of wire pairs should comply with LAN system impedance of 100, 120 or 150 Ω.

6.14. Delay and Skew Test

This test determines the delay of a test signal that was fed at one end of the cable to the other end of the cable. The delay skew indicates the difference between the measured delay of the corresponding wire pair and the wire pair with the lowest delay value. The limits specified for delay and skew depend on selected cable type.

Illustration 6.14. Delay and Skew Test

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