Fishnet beacons, also known as Drift Nets and Fishing Buoy Transmitters, are low power transmitters which periodically send CW identifiers followed by a carrier. The average repetition rate is about 4 minutes. They are battery powered and use fairly small and inefficient antenna, however they can be heard for hundreds or even thousands of miles. Fishnet beacons are can be found between 1.6 and 4 MHz, and are most often found in and above the 160-meter amateur radio band. They are typically used by fishermen to locate nets, hence the name.
There are reports of similar beacons operating in the 26-30 MHz range (including inside the 11 meter CB band and 10-meter amateur band). They follow a very similar format, transmitting a varying-number of characters ID with low power.
Typical transmit power is in the 3 to 10 watt range.
List of fishnet beacons