Keywords
radio
interference, DSL, PLT, PLC, emissions, broadcasting, AM,
NB30 MPT1570
|
Abstract
Systems
which re-use mains or phone wiring for communications
purposes (such as xDSL, PLT or home-networking systems)
are currently of interest. As well as their obvious
benefits they have the potential to cause interference
to radio systems, especially to receivers in the
immediate vicinity.
Various
limits to the emissions from these systems have already
been proposed. One is already law in Germany, and
covers a wide range of frequencies. Another, covering
the LF/MF range, is agreed and in the process of
becoming law in the UK. A CEPT Working Group, CEPT
SE35, is considering the issue and is tasked with
drafting an ERC Recommendation and Report - although
the final decision will be made by a higher body.
This
paper considers the various proposals for limits
that are under discussion in CEPT SE35 at the time
of writing and determines the degree of protection
that they offer to reception of broadcasting services
in the general vicinity of the datacarrying cables.
(A separate BBC R&D White
Paper, no. WHP 004, considers the cumulative
effects of such emissions on far-off receivers).
The
conclusion is that none of the limits proposed so
far offers adequate protection to broadcast reception.
Unfortunately this is especially true of the limits
that have already gained legal status in Germany
and the UK. However, a proposal based on limiting
the increase in the noise floor appears to offer
promise and forms the subject of a separate paper.
It
is hoped that the calculations presented here will
guide regulators in setting limits to the emissions
from potentiallywidespread xDSL/PLT/etc. systems
so that radio users may be assured adequate protection
from interference. |
