ZyXEL Communications PLA-470 V2 - V3.0.5 Installationsanleitung PDF herunterladen (Seite 41)

Depending on the electronic components used, the analog interface has a char-

acteristic “sensitivity” that affects its ability to transmit the PLC signal without

excessive degradation. This sensitivity is modeled by an impedance between the elec-

trical wiring and the digital circuitry of the device.

Modeling Electrical Networks

Modeling an electrical network allows us to anticipate phenomena that occur dur-

ing data transmission (perturbations, lost connections, and so forth) and to propose

a representation that will best support the engineering of the network.

Whether electrical networks are considered in a public context (the case of elec-

trical distribution networks) or that of a private home or business, modeling them is

a difficult technical subject that requires consideration of numerous parameters

(topology, nature of the wiring, perturbations, devices connected to the network,

time of day, and so forth).

Since no tool exists for exhaustive modeling of electrical networks, the engineer-

ing of PLC telecommunications networks is limited to modeling the physical trans-

port layer of the PLC signal.

Measurements carried out on electrical networks have allowed us to quantify

the average impedance of an electrical line for high frequencies of the type used by

PLC equipment.

Figure 2.4 illustrates the impedance curve in ohms (impedance as an absolute

value) as a function of frequency. This impedance varies from 5 to 150 ohms for

PLC frequencies.

22 Architecture

Figure 2.4 Average impedance of an electrical line as a function of frequency

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ZyXEL Communications PLA-470 V2 - V3.0.5 Installationsanleitung Seite 41