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6.15.1
Capacitance Test Error
The higher the capacitance, the higher the error rate. Due to transport and installation of
the cable, minor changes in capacitance are normal. Connectors and patch cords also
influence capacitance values.
6.16
ACR-N (ACR) Test and Power Sum ACR-N (Power Sum ACR) Test
The ACR-N (ACR) test determines the loss-crosstalk distance by means of a mathematical
comparison (difference calculation) of the loss and NEXT test results. The differences
between the measuring values of a wire pair indicate whether transmission interferences are
likely to occur in the respective wire pair.
The ACR-N (ACR) measurement is calculated from pair to pair. Power Sum ACR-N (Power
Sum ACR) measurement is calculated by summation of NEXT values between a selected
wire pair and three other wire pairs of the same cable.
Fig. 85 ACR-N (ACR) / Power Sum ACR-N (Power Sum ACR)
6.16.1
ACR-N (ACR) Test and Power Sum ACR-N (Power Sum
ACR) Test Error
A large difference between the measuring values is preferable, since this indicates a strong
signal and minor perturbations.
6.16.2
Troubleshooting ACR-N (ACR) Test and Power Sum ACR-N
Test Error
For information on troubleshooting, refer to the corresponding sections on NEXT and loss
test.
6.17
Headroom Test
The headroom test is a mathematical analysis of the data calculated during the preceding
test. The sum of Power Sum ACR-N (Power Sum ACR) test (i.e. corresponding value of
worst case wire pair after normalization of wire pair loss over 100 meters) and the
additional margin between the worst case Power Sum NEXT-value and the limit for Power
Sum NEXT.
LanTEK III
User Manual
161809 Iss 2
Page67
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