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Tap ports on a passive infrastructure are the easy way to monitor a transport network. Implemented as a passive fiber-optical coupler, they usually are fused couplers, designed to take out a small portion (typically 1-10%) of the passing light signals. This tapped-out light can then be used for various intents.
The primary use of such monitoring is maintenance, inspection or trouble shooting of a transport network. This is either on demand or on a permanent base, without influencing or interrupting data traffic. Tap ports can also be very convenient for secretly taping and intercepting data traffic without being noticed by the end user (if the tap is dimensioned in the appropriate way). This, of course(!), is only meant for crime and terror prevention! Great choice for any security relevant application.
Usually the best location to place a tap port is at the ends of the transmission fiber route. Here all accumulated traffic is present and just one tap is needed to analyze all signals. In many scenarios, optical multiplexers are the last element, acting as concentrators at the beginning and the end of fiber routes. The most common place to install a tap, is inside the optical W/C/DWDM passive mux unit. Here it is internally connected to the common input / output port.
Permanent monitoring is achieved the easiest way by connecting the tap signals to standard pluggable transceivers (Rx side). Doing so, it's possible to monitor changing power levels online. Reasons can be, that transceivers reaching their end of life, fiber aging or (un)lawful traffic interception. Yet, a far better accuracy is achieved with power meters. Taps alternatively can also be placed on individual channels, enabling individual monitoring of specific senders / receivers, evidently with more monitoring efforts.
Most important in any case, is the proper dimension of the tap i.e. how much power is required to be forked out. From the monitoring point of view, the higher the tapped power, the easier is the monitoring task. On the other hand a higher taping percentage will reduce the power for the data transmission and eventually prohibit it.
It is important to check the optical link budget when designing the tap.
So, when designing the tap, it is important to have the optical link budget and applied transceiver power budgets in mind, as well as the threshold levels of the monitoring equipment.
We can provide any of our mux solutions with any tap solution you need.