32
NETWORKING
Line
Communication
By Erkka Herola, Account
Manager, Anritsu
Erkka Herola discusses how to
recognise and find interference.
Introduction
Governments and utilities are enthusiastically
supporting the adoption of smart metering.
Governments because of the scope it offers to reduce
energy consumption, and utilities because of the
way it can improve management of their power
generation capacity. The roll out of smart metering
has brought with it the widespread implementation
of Power Line Communication (PLC), a low data-rate,
long-range communications protocol that allows the
same cable to carry both mains power and signals.
Interestingly, PLC is a form of radio frequency (RF)
communication: this seems surprising, because the
air is the normal medium for RF transmissions, rather
than mains power cable. Nevertheless, PLC utilises
a modulated carrier, albeit one operating at lower
frequencies than most commercial radio systems with
an air interface.
Like any RF link, the reliability and proper
functioning of a PLC link calls for transmission
and reception to occur at a bit-error-rate below
a maximum threshold, and this in turn requires
operation at a specified carrier-to-interference (C/I)
ratio or signal-to-noise ratio (SNR). In an RF system,
the higher the C/I ratio, the greater the distance the
transmitter may be from F