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.
A
separate BBC R&D White
Paper, no. WHP 012, 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 data-carrying
cables. It concludes 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.
This
paper develops an alternative proposal based on limiting
the increase in the noise floor, and shows how a
practicably-applicable limit can be logically developed
from this very justifiable starting principle. It
is shown that the proposed limit provides reasonable
protection to outdoor reception for all radio services.
Some compromise in performance has to be accepted
by listeners using antennas indoors for reception
- this applies primarily to broadcast reception.
Regulators
are urged to ensure that any emissions limits they
bring forward provide a level of protection to radio
services which is at least equal to that offered
by the proposal presented here. Anything less stringent
cannot be claimed to protect radio users - even this
proposal involves some compromise on the part of
listeners. |
