Whenever tests are performed on fiber optic networks, the results are displayed on a meter readout in dB. Optical loss is measured in dB while optical power is measured in dBm. Loss is a negative number (like -3.2 dB), as are most power measurements. Confused? Many fiber optic techs are too.
When one of the coaches was asked before the “big game” what would be the key to his team’s success, he said, “executing the fundamentals.” While blocking, tackling, passing and catching may work for football, Ohm’s and Kirchhoff’s Laws are fundamental to understanding any power quality issue.