International Beacon Project
A worldwide network of HF beacons for assessing ionospheric propagation.
The International Beacon Project (IBP) is a global network of 18 continuous wave (CW) beacons that transmit on five set frequencies within the high frequency band. Its purpose is to help amateur and commercial HF radio users gauge current ionospheric signal propagation conditions. The Northern California DX Foundation (NCDXF) and the International Amateur Radio Union (IARU) jointly coordinate the project.
The first beacon began operating in 1979 from Northern California. It transmitted a one-minute signal every ten minutes on 14.1 MHz, using custom-built transmitter and controller hardware. The signal included the beacon’s call sign in Morse code at 100 watts, four nine-second dashes at 100, 10, 1, and 0.1 watts, and a sign-out at 100 watts. The NCDXF and seven partner organizations from the United States, Finland, Portugal, Israel, Japan, and Argentina ran the initial network. Because building beacon hardware proved difficult, each site used a Kenwood TS-120 transceiver controlled by a custom beacon controller. The network operated solely on 14.1 MHz, and the beacon format remained unchanged.
In 1995, work began to upgrade the network to operate on five designated HF frequencies. The new beacons used Kenwood TS-50 transceivers with an upgraded controller. The number of partner organizations grew to 18, and a new ten-second beacon format was adopted.
Beyond aiding amateur radio operators, the project has helped scientists study the ionosphere, improve propagation prediction models, and assist with radio direction finding.
The beacons transmit continuously on 14.100, 18.110, 21.150, 24.930, and 28.200 MHz. Each beacon sends its signal once on each frequency, starting at the lowest and moving to the highest, followed by a 170-second pause while other sites transmit on the same frequencies. The cycle then repeats. Each ten-second transmission consists of the beacon’s call sign sent at 22 words per minute, followed by four dashes. The call sign and first dash are sent at 100 watts; the next three dashes are at 10, 1, and 0.1 watts. All transmissions are coordinated using GPS time, so all 18 beacons transmit in succession on a given frequency once every three minutes.
The hardware uses commercial HF transceivers (Kenwood TS-50 or Icom IC-7200) keyed and coordinated by a purpose-built beacon controller.
- Number of beacons
- 18
- Frequencies
- 14.100 MHz, 18.110 MHz, 21.150 MHz, 24.930 MHz, 28.200 MHz
- First beacon operational
- 1979
- First beacon location
- Northern California
- Coordinating organizations
- Northern California DX Foundation (NCDXF) and International Amateur Radio Union (IARU)
- Transmission power levels
- 100 W, 10 W, 1 W, 0.1 W
- Beacon format duration
- 10 seconds
Lore & Background
The first beacon of the International Beacon Project began operations in 1979 from Northern California using the call sign . It transmitted a 1-minute-long beacon every 10 minutes on 14.1 MHz, using custom built transmitter and controller hardware. The signal consisted of the beacon's call sign in Morse code at 100 watts, four 9-second dashes at 100 W, 10 W, 1 W, and 0.1 W, followed by sign-out at 100 watts. The Northern California DX Foundation and seven partnering organizations from the United States, Finland, Portugal, Israel, Japan, and Argentina operated the first iteration. Due to hardware difficulties, each site used a Kenwood TS-120 transceiver keyed and controlled by a custom built beacon controller, operating solely on 14.1 MHz.
In 1995, work began to improve the network to operate on five designated HF frequencies. The new beacons used Kenwood TS-50 transceivers keyed and controlled by an upgraded beacon controller unit. The number of partner organizations expanded to 18, and a new 10-second beacon format was adopted. As of January 2024, the network operates 18 beacons transmitting around the clock on 14.100, 18.110, 21.150, 24.930, and 28.200 MHz. Each beacon transmits once on each frequency in sequence from low to high, followed by a 170-second pause, then the cycle repeats. Each 10-second transmission consists of the call sign at 22 words per minute and four dashes; the call sign and first dash are at 100 watts, with subsequent dashes at 10 W, 1 W, and 0.1 W. All transmissions are coordinated using GPS time, so all 18 beacons transmit in succession once every 3 minutes on a given frequency.
Reader's Guide
The International Beacon Project has served as a practical tool for amateur radio operators to understand HF radio propagation in real time. By transmitting at multiple power levels on five frequencies spanning the HF band, the network allows users to compare signal strength and path conditions across different bands and times of day. The project's coordination by the Northern California DX Foundation and the International Amateur Radio Union has ensured consistent operation and global coverage. Beyond amateur use, the project has aided scientists in better understanding the Earth's ionosphere, improved prediction models, and assisted in radio direction finding. The beacon network's design—using commercial HF transceivers (Kenwood TS-50 or Icom IC-7200) keyed by a purpose-built hardware controller—has made it reliable and reproducible. The use of GPS time synchronization ensures precise timing, enabling listeners to identify which beacon is transmitting at any given moment. The project's longevity, from its first beacon in 1979 through expansions in 1995 to 18 sites, demonstrates its sustained value to the radio community. The network continues to provide a free, continuous resource for assessing propagation conditions, supporting both casual operators and serious propagation researchers.
Did You Know?
- The first beacon began operations in 1979 from Northern California.
- The network originally used Kenwood TS-120 transceivers, later upgraded to TS-50 or Icom IC-7200 models.
- All beacon transmissions are coordinated using GPS time, with all 18 beacons transmitting in succession once every 3 minutes on a given frequency.
More in Radio Propagation 1-24
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced