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NCDXF/IARU Beacon Network

NCDXF Logo IARU logo

The NCDXF, in cooperation with the IARU, constructed and operates a worldwide network of high-frequency radio beacons on 14.100, 18.110, 21.150, 24.930, and 28.200 megaHertz. These beacons help both amateur and commercial high-frequency radio users assess the current condition of the ionosphere. The entire system is designed, built and operated by volunteers at no cost except for the actual price of hardware components, shipping costs, and so on.

Three articles about the beacons have appeared in QST within the past few years and these articles are now available online at the IARU web site at These articles have a lot of interesting details about the beacons. Most of the hardware used in the beacons is regular commercial equipment, but the controller is specially designed and is described in detail in Beacon Controller.

Stan Huntting, KW7KW, wrote, "There are at least two possible explanations for an apparently dead band: 1) propagation is poor, or 2) no one is transmitting. The NCDXF/IARU International Beacon Network addresses the second of these possibilities by insuring that reliable signals are always on the air, around the clock, from fixed locations worldwide." With three minutes of listening for the beacons, one can find out either where a particular band is open or which band has the best propagation to a particular part of the world.

In principle, one can simply listen on the beacon frequencies and copy the CW callsigns of the various beacons to figure out where the band is open, but in practice, not every ham operator can copy calls at twenty-two words per minute and some beacons may be heard at too low a signal strength to catch the call. Because the beacons transmit at known times, it is easy to know which beacon one is hearing without actually copying the CW callsign. Since the beacons are running one hundred watts to a vertical, even a weak beacon signal may indicate a path with excellent propagation for stations using higher power and directive antennas.

In order to know which beacon is transmitting at any particular time, one can either refer to the Beacon Transmission Schedule or use your computer and one of the Programs to Help Beacon Listeners. If you want to know where to point your antenna or decide which beacons are the most interesting to you, you can refer to the Beacon Locations. If you have a computer and a computer-compatible radio and would like a record of when various beacons can be heard at your QTH, you will want to learn about Automated Beacon Monitoring.

In time, we hope to have many automated receiving stations around the world which post a record of what beacons they have heard on the internet for all to use. Such a setup raises many interesting questions about how to effectively display such massive amounts of information.

If you like the beacons, we hope you will support those who provide Support for the Beacons and you will surely want to keep up with beacon developments by reading the latest Beacon News and the Early Beacon History. If you are bothered by interference from other stations when you listen to the beacons, you may want to read about Beacon Interference.