Resistance Test Error; Next, Acr-F (Elfext) And Power Sum - IDEAL Networks LanTEK III Manual

6.8.1

Resistance Test Error

All four wire pairs of a transmission line within the network should have approximately the
same resistance. If the resistance value of a wire pair exceeds the limit, the test is
considered failed.
6.9

NEXT, ACR-F (ELFEXT) and Power Sum

In an Autotest, crosstalk at the near and far end of the cable is measured with NEXT (Near
End Cross Talk) and ACR-F (ELFEXT) tests. High crosstalk levels can result in frequent
recurrences, damage to data and other interferences that impair transmission rate.
The NEXT test determines interfering effects (crosstalk) of a transmitting wire pair on the
adjacent wire pair in the same cable. NEXT is measured on Display handset (DH) and
Remote handset (RH).
• FEXT test and NEXT measurement are similar; the only difference is that in FEXT
test the transmissions emanate from Remote handset (RH) and that crosstalk is
determined at Display handset (DH).
• NEXT measurements are performed on each cable end and for all wire pair
combinations (pair 1-2 to 3-6 etc.). Thus, a total of 12 measurements is performed.
•
ACR-F (ELFEXT) measurements take place with the Display handset (DH) and the
Remote handset (RH) on both cable ends and for all possible wire pair
LanTEK III
User Manual
Fig. 75 NEXT, ACR-F (ELFEXT) and Power Sum
1
2
3
6
4
5
7
8
Fig. 76 Effect of Adjacent Pair
2
1
6
3
5
4
8
7
161809 Iss 2
Page62