ARLA/CLUSTER: Nova Zelândia chegou à conclusão que a interferência nas micro-ondas vinha directamente dos barcos de pesca

[João Costa > CT1FBF]

Fishy business

Recently the Christchurch (New Zealand) radio inspectors were involved
with a commercial interference case affecting a major microwave link
in the upper South Island.

The microwave operator was able to identify that the link was only
being affected when the same fishing vessel crossed its path in the
Cook Strait. This led the inspectors to a number of conclusions
however the only possible way to determine the interference was to
position themselves on a hilltop overlooking the Strait. Using a
microwave dish and sufficient gain they were able to see the
interfering signals radiating from the fishing boat. By utilising the
AIS vessel tracking website their position was verified.

It was obvious that the fishing boat was the cause of the
interference, however what was not known was why it was emitting these
transient signals. The radio frequency signature of the noise looked
to be very similar to the S Band radar aboard the vessel.

The fishing company was called and the S Band radar was turned off.
Immediately the noise ceased and it was obvious that this was the
cause of the interference. A subsequent letter was sent to the fishing
company and the S Band radar’s magnetron was replaced.