SIGS BELOW 160

[ve6pg]

...hi from tim...ok, i'm hearing those drift net beacons on 160, but i am hearing digital, stuff below 1800, abt 1775, 1745, etc...anyone know what this stuff is?..what kind of mode, and traffic it handles?....
  very strong here....sk...

[k4kyv]

Radiolocation beacons.  They are used to help ships and planes locate such things as offshore oil platforms.  Usually a strong carrier modulated every  10 seconds or so with a burst of digital data.

They are also allocated 1900-2000 kHz.  There used to be several in that part of the band, and at least in US, they have priority over amateur stations.  Lately, the only one that is audible is on about 1952 kHz, and it is on the air only sporadically.  I suspect the GPS system has about rendered these things obsolete.

At one time the radiolocation industry was lobbying hard to gain exclusive use of 1900-2000. The reason for the allocation in the ham band was that they originally were assigned 1600-1800 kHz, and when the AM broadcast band was expanded to 1700 kHz, they were given 1900-2000 to "reaccomodate" the beacons that were displaced by the expanded broadcast band.

At one time the spectrum between the AMBC and 160m was packed with beacons.  Now there are only about a half dozen still operating.