Fluke Networks CertiFiber Pro Users Manual - Manual (Page 131)

Chapter 3: How to Certify Twisted Pair Cabling
Twisted Pair Autotest Results
109
CMRL (Common-Mode Return Loss)
Common-mode return loss is the difference (in dB) between the
power of a common-mode signal applied to a wire pair and the
power of the common-mode signal reflected back. The signal
reflections are caused by variations in the cable’s impedance.
At the time this manual was released, no test standards required
CMRL measurements. The Autotest includes the CMRL test for
troubleshooting purposes only.
Figure 54 shows the CMRL plot.
GPU92.PNG
Figure 54. CMRL Plot