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Narrowband power line communication
Narrowband power line communications started soon after the beginning of
wide-spread electrical power supply. Around the year 1922 the first carrier
frequency systems began to operate over high-tension lines in the frequency
range 15 to 500 kHz for telemetry purposes, and this continues to the present
time . Consumer products such as baby alarms have been available at least since
1940 .
In the 1930s, ripple carrier signalling was introduced on the medium (10-20 kV)
and low voltage (240/415V) distribution systems. For many years the search has
been going on for a cost effective bi-directional technology suitable for
applications such as remote meter reading. For example, the Tokyo Electric Power
Co was running experiments in the 1970’s which reported successful
bi-directional operation with several hundred units . Since the mid-eighties
there has been a surge of interest in using the potential of digital
communications techniques and digital signal processing. The drive is to produce
a reliable system which is cheap enough to be widely installed and able to
compete cost effectively with wireless solutions. The narrowband powerline
communications channel presents many technical challenges. A mathematical
channel model and a survey of work can be found in reference no. 5 .
Applications of mains communications vary enormously, as would be expected of
such a widely available medium. One natural application of narrow band power
line communication is the control and telemetry of electrical equipment such as
meters, switches, heaters and domestic appliances. There are a number of active
developments that are considering such applications from a systems point of
view, such as 'Demand Side Management' . In this, domestic appliances would
intelligently co-ordinate their use of resources, for example limiting peak
loads.
Control and telemetry applications include both 'utility side' applications,
which involves equipment belonging to the utility (i.e. between the supply
transformer substation up to the domestic meter), and 'consumer-side'
applications which involves equipment in the consumer's premises. Possible
utility-side applications include automatic meter reading, dynamic tariff
control, load management, load profile recording, credit control, pre-payment,
remote connection, fraud detection and network management , and could be
extended to include gas and water.
A project of EDF, France, includes demand side management, street lighting
control, remote metering and billing, customer specific tariff optimisation,
contract management, expense estimation and gas applications safety .
There are also many specialised niche applications which use the mains supply
within the home as a convenient data link for telemetry. For example, in the UK
and Europe a TV audience monitoring system uses powerline communications as a
convenient data path between devices that monitor TV viewing activity in
different rooms in a home and a data concentrator which is connected to a
telephone modem.
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