Problem : Strange behaviors with line quality and alarms when passive tapping with the PrimenetMM board. Practically this demonstrates itself as alarms and/or drop links on the PrimenetMM digital logging board or as a negative effect on the tapped installation itself.
More specifically this is a layer 1 issue which demonstrates itself as span alarms and bit errors. It is caused by a impedance mismatch which causes signal reflection that effects pulse shape.

Solution: The solution is the installation of 100 ohm resistors inline with the tap cable. We recommend the resistors are placed close to the tap point. A document detailing their installation into a cable can be found here -

Please note: Not all installations require these resistors.