Topband: R: fishing buoys

[Tom Rauch]

> japanese sea, and they were still there in the morning, so I suppose
> they could be somewhere in the Northern Sea.... I put here your same
> question: what are they and what is the purpose?

There are markers that send a long dash followed by a normal CW 
sounding ID with a mix of letters and numbers. They only transmit 
every few minutes repeating the ID and a long dash a few times.These 
are buoys used to mark multiple-hook drift lines used for fishing. I 
suppose they could be used for drift nets, but no one would fish with 
an illegal drift net now would they??

The buoys are very low power ( a few watts) with short antennas, and 
are all over the world now, and the people who plant them tend to use 
USB transmitters near the frequency of the buoys from time to time to 
chat.

We have other markers here in the United States and Canada that are 
problems, but I'm not sure if they are a world-wide problem or not. 
We have Airport non-direction beacons (called NDB's here) operating 
from around 220-440kHz.

They are poorly designed transmitters generally running low power 10-
100 watts. They usually have modulated CW identifiers. In the USA, 
they have three letter callsigns and are on continuously with the ID 
repeating every few seconds. 

NDB markers often transmit harmonics of the unmodulated carrier, and 
it is the inverse of the CW! A dash becomes a long space, a dot a 
short space, and a space becomes a long dash. 

Here in GA, I can identify no less than a dozen of these things, some 
from as far away as Arizona and Wisconsin. You may have a similar 
problem if your airports use NBD's of the same quality as US 
Airports. The amazing part is the power is so low, yet they cause 
problems over a wide area. The root of that is the systems have 
virtually no harmonic filtering. They depend on all the stages being 
perfectly linear and the loading coil (that is usually series 
resonant on 160 meters) to suppress harmonics.  

While the root of the problem is with the manufacturer(s). At least 
one manufacturer advises FAA certified techs to use an oscilloscope 
to check for distortion and harmonics. This compounds the problem 
because most FAA certified techs are positive they are "doing it 
right" and won't take any input from anyone except the FAA.

Even the FCC has a tough time dealing with them.73, Tom W8JI
W8JI@contesting.com