The International Beacon Project (IBP) is a worldwide network of radio propagation beacons. It consists of 18 continuous wave (CW) beacons operating on five designated frequencies in the high frequency band.[1] [2] The IBP beacons provide a means of assessing the prevailing ionospheric signal propagation characteristics to both amateur and commercial high frequency radio users.[1] [2]
The project is coordinated by the Northern California DX Foundation (NCDXF) and the International Amateur Radio Union (IARU). The first beacon of the IBP started operations from Northern California in 1979. The network was expanded to include 8 and subsequently 18 international transmission sites.[1] [2]
The first beacon was put into operation in 1979 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 transmitted in Morse code at 100 watts, four 9 second long dashes, each at 100 watts, 10 watts, 1 watt, and 0.1 watt, followed by sign-out at 100 watts.[3]
Northern California DX Foundation and seven partnering organizations from the United States, Finland, Portugal, Israel, Japan, and Argentina operated the first iteration of the beacon network. Due to difficulties encountered in building beacon hardware, each site used a Kenwood TS-120 transceiver keyed and controlled by a custom built beacon controller. The network operated on 14.1 MHz and the beacon format remained unchanged.[3]
In 1995, work began to improve the existing beacon network, so it could operate on 5 designated frequencies on the high frequency band. The new beacon network used Kenwood TS-50 transceivers keyed and controlled by an upgraded beacon controller unit. The number of partner organizations were expanded to 18 and the new 10 second beacon format was adopted.[3]
Beyond helping amateur radio operators better understand HF radio propagation the project has aided scientists in better understanding the earths ionosphere,[4] improved prediction models,[5] and aided in radio direction finding.[6]
The beacons transmit around the clock on the frequencies[1] [7]
18.110 MHz
21.150 MHz
24.930 MHz
Each beacon transmits its signal once on each frequency, in sequence from low (14.100 MHz) to high (28.200 MHz), followed by a 130 second pause during which beacons at other sites transmit in turn on the same frequencies, after which the cycle repeats.[7] Each transmission is 10 second-long, and consists of the call sign of the beacon transmitted at 22 words per minute followed by four dashes. The call sign and the first dash is transmitted at 100 watts of power. Subsequent three dashes are transmitted at 10 watts, 1 watt, and 0.1 watt respectively.[7]
All beacon transmissions are coordinated using GPS time. As such, at a given frequency, all 18 beacons transmit in succession once every 3 minutes.[3]
Beacons transmit using commercial HF transceivers (Kenwood TS-50 or Icom IC-7200) keyed and coordinated by a purpose-built, hardware beacon controller.[2]
The International Beacon Project operates the following beacons as of January 2024.[8]