NCDXF/IARU International Beacon Project


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.

The first beacon began transmissions from Northern California in 1979 and was so successful that the IARU proposed a world wide network of beacons operating 24 hours a day. Over the next few years the network was expanded slowly. The current system of 18 beacons began operation in 1995 and has been in continuous operation ever since. Read More...

Three articles about the beacons appeared in QST and are reproduced by permission of the ARRL. These articles have a lot of interesting details about the background and history of the beacons.

The transmitter used has been the Kenwood TS-50s for the past 20 years. The controller was designed by hams and is described in detail on the Beacon Controller page. In 2015, a new controller design was implemented for use with new Icom IC-7200 radios. The new controller and radios will gradually replace the old equipment over the coming months.

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, which shows the currently transmitting beacons by frequency, 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 using the FAROS program or Skimmer which posts information to the Reverse Beacon Network.

If you find the beacons useful, 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 on Twitter 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.

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