Chapter 3
Structured Cable Field Calibration and Testing
3-31
ACR and Power Sum ACR Test
The ACR (Attenuation-to-Crosstalk Ratio) test performs a mathematical comparison
(difference calculation) between the results of the Attenuation and NEXT tests. The
difference reading between each pair gives an indication of how problem-free the
cable pair will be for transmissions.
The ACR measurements are calculated pair-to-pair. The Power Sum ACR
measurements are calculated by summing the NEXT between a selected pair and the
other three pairs in the same cable sheath.
Figure 3-21: ACR and Power Sum Test Screens
ACR and Power Sum ACR Errors
A large difference reading is desirable, since it indicates a strong signal and little noise
interference.
Troubleshooting ACR and Power Sum ACR Problems
Refer to the NEXT and Attenuation troubleshooting suggestions.
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