Radio propagation beacon

An amateur radio propagation beacon is a radio beacon, whose purpose is the investigation of the propagation of radio signals. Most radio propagation beacons use amateur radio frequencies. They can be found on LF, MF, HF, VHF, UHF, and microwave frequencies. Microwave beacons are also used as signal sources to test and calibrate antennas and receivers. An amateur radio propagation beacon is a radio beacon, whose purpose is the investigation of the propagation of radio signals. Most radio propagation beacons use amateur radio frequencies. They can be found on LF, MF, HF, VHF, UHF, and microwave frequencies. Microwave beacons are also used as signal sources to test and calibrate antennas and receivers. The International Amateur Radio Union (IARU) and its member societies coordinate beacons established by radio amateurs. Most beacons operate in continuous wave (A1A) and transmit their identification (call sign and location). Some of them send long dashes to facilitate signal strength measurement. A small number of beacons transmit Morse code by frequency shift keying (F1A). A few beacons transmit signals in digital modulation modes, like radioteletype (F1B) and PSK31 (G1B). Amateur experiments in the 2200-meter band (135.7-137.8 kHz) often involve operating temporary beacons. In the United States and Canada, unlicensed experimenters called Lowfers establish low power beacons on radio frequencies between 160 kHz and 190 kHz. The International Amateur Radio Union Region 2 (North and South America) bandplan for 160 meters reserves the range 1999 kHz to 2000 kHz for propagation beacons. Most high frequency radio propagation beacons are found in the 10 meters (28 MHz) frequency band, where they are good indicators of Sporadic E ionospheric propagation. According to IARU bandplans, the following 28 MHz frequencies are allocated to radio propagation beacons: Due to unpredictable and intermittent long distance propagation, usually achieved by a combination of ionospheric conditions, beacons are very important in providing early warning for 6 meter (50 MHz) openings. Beacons operate in the lower part of the band, traditionally in the range 50.000 MHz to 50.080 MHz. The IARU is encouraging individual beacons to move to 50.4 MHz to 50.5 MHz to assist with the establishment of the Synchronised 50 MHz Beacon Project. In the United States, the Federal Communications Commission (FCC) only permits unattended 6 meter beacon stations to operate between 50.060  and 50.080 MHz.