
Methods for Accessing the Medium
In PLC networks, the method for accessing the medium consists of connecting the
PLC devices to the electrical network in order to obtain the best performance at the
physical level and the best useful throughput at the upper layer level as a result.
To connect a PLC device to the electrical network, there are two different meth-
ods, called “couplings”: capacitive coupling and inductive coupling.
The capacitive coupling is the coupling mostly used by PLC modems. The term
“capacitive” means that the PLC modem connected to the outlet is viewed as a
capacitance (i.e., a capacitor). Figure 7.22 illustrates the operating principle of
capacitive coupling.
140 Equipment
Figure 7.21 Wingoline telephone PLC modem with two RJ-11 telephone interfaces
Figure 7.22 Capacitive coupling principle
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