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Hub AI
80-meter band AI simulator
(@80-meter band_simulator)
Hub AI
80-meter band AI simulator
(@80-meter band_simulator)
80-meter band
The 80 meter or 3.5 MHz band is a span of radio frequencies allocated for amateur use, from 3.5–4.0 MHz in North and South America (IARU and ITU Region 2); generally 3.5–3.8 MHz in Europe, Africa, and northern Asia (Region 1); and 3.5–3.9 MHz in south and east Asia and the eastern Pacific (Region 3). The upper portion of the band, which is usually used for phone (voice), is sometimes referred to as 75 meters; however, in Europe, "75 m" is used to name an overlapping shortwave broadcast band between 3.9–4.0 MHz used by a number of national radio services.
Because high absorption in the ionosphere's Sun-activated D layer persists until nightfall, 80 meters is usually only good for local communications during the day, and hardly ever good for communications over intercontinental distances during daylight hours. But it is the most popular band for regional communications networks from the late afternoon through the night time hours.[according to whom?] At night, 80 m is usually reliable for short- to medium-distance contacts, with average distances ranging from local contacts within 200 miles / 300 km out to a distance of 1,000 miles / 1,600 km or more at night – even worldwide – depending on atmospheric and ionospheric conditions.
The nominal "80 meter" band begins at 3.5 MHz (85.7 m wavelength) and goes up to 4.0 MHz (74.9 m wavelength). The upper part of the band, mostly used for voice, is often referred to as 75 meters, since in Region 2, the wavelengths in that section are between 80–75 meters (adjacent to or overlapping a shortwave broadcast band called by the same name: "75 m").
80 meters can be plagued with noise: The same ionospheric refraction that makes long-distance shortwave propagation possible also traps terrestrial noise under the ionosphere, preventing it from dissipating into space, which quiets down radio bands at higher frequencies, above ~20 MHz. The 80 m rural noise floor is mostly determined by noise produced by distant tropical thunderstorms and cumulative regional sources of human-made static. The urban and suburban 80 m noise floor is typically set by the amount of noise generated locally, from electrical machinery and household electronics, and is generally 10–20 dB stronger than typical rural noise.
On 80 meters, nearly all areas of the world are subject to weather-induced noise from regionally local thunderstorms, and combined distant lightning strikes from tropical thunderstorms that perpetually supply world-wide a continuous source of radio static.
The 80 meter band is favoured for ragchews between amateurs within a range of 500 miles / 800 km. During contests the band is filled with activity beginning before sunset and continuing all through the night.
The ionosphere's D layer significantly affects the 80 meter band by absorbing signals. During the daylight hours, a station in middle or high latitudes using 100 watts and a simple dipole antenna can expect a maximum communication range of 200 miles (320 km), extending to a few thousand miles or more at night.
Global coverage can be routinely achieved at high latitudes during the late fall and winter, by stations using modest power and common antennas. The higher background noise on 80 meters, especially when combined with higher ionospheric absorption, causes transmitting stations with higher effective radiated power to have a decided advantage in being heard by long-distance receiving stations. With very high transmitting antennas or large vertically polarized arrays and full legal power, reliable worldwide communications occurs over nighttime paths. Good receiving antennas have far more modest requirements to reliably get signals from worldwide sources.
80-meter band
The 80 meter or 3.5 MHz band is a span of radio frequencies allocated for amateur use, from 3.5–4.0 MHz in North and South America (IARU and ITU Region 2); generally 3.5–3.8 MHz in Europe, Africa, and northern Asia (Region 1); and 3.5–3.9 MHz in south and east Asia and the eastern Pacific (Region 3). The upper portion of the band, which is usually used for phone (voice), is sometimes referred to as 75 meters; however, in Europe, "75 m" is used to name an overlapping shortwave broadcast band between 3.9–4.0 MHz used by a number of national radio services.
Because high absorption in the ionosphere's Sun-activated D layer persists until nightfall, 80 meters is usually only good for local communications during the day, and hardly ever good for communications over intercontinental distances during daylight hours. But it is the most popular band for regional communications networks from the late afternoon through the night time hours.[according to whom?] At night, 80 m is usually reliable for short- to medium-distance contacts, with average distances ranging from local contacts within 200 miles / 300 km out to a distance of 1,000 miles / 1,600 km or more at night – even worldwide – depending on atmospheric and ionospheric conditions.
The nominal "80 meter" band begins at 3.5 MHz (85.7 m wavelength) and goes up to 4.0 MHz (74.9 m wavelength). The upper part of the band, mostly used for voice, is often referred to as 75 meters, since in Region 2, the wavelengths in that section are between 80–75 meters (adjacent to or overlapping a shortwave broadcast band called by the same name: "75 m").
80 meters can be plagued with noise: The same ionospheric refraction that makes long-distance shortwave propagation possible also traps terrestrial noise under the ionosphere, preventing it from dissipating into space, which quiets down radio bands at higher frequencies, above ~20 MHz. The 80 m rural noise floor is mostly determined by noise produced by distant tropical thunderstorms and cumulative regional sources of human-made static. The urban and suburban 80 m noise floor is typically set by the amount of noise generated locally, from electrical machinery and household electronics, and is generally 10–20 dB stronger than typical rural noise.
On 80 meters, nearly all areas of the world are subject to weather-induced noise from regionally local thunderstorms, and combined distant lightning strikes from tropical thunderstorms that perpetually supply world-wide a continuous source of radio static.
The 80 meter band is favoured for ragchews between amateurs within a range of 500 miles / 800 km. During contests the band is filled with activity beginning before sunset and continuing all through the night.
The ionosphere's D layer significantly affects the 80 meter band by absorbing signals. During the daylight hours, a station in middle or high latitudes using 100 watts and a simple dipole antenna can expect a maximum communication range of 200 miles (320 km), extending to a few thousand miles or more at night.
Global coverage can be routinely achieved at high latitudes during the late fall and winter, by stations using modest power and common antennas. The higher background noise on 80 meters, especially when combined with higher ionospheric absorption, causes transmitting stations with higher effective radiated power to have a decided advantage in being heard by long-distance receiving stations. With very high transmitting antennas or large vertically polarized arrays and full legal power, reliable worldwide communications occurs over nighttime paths. Good receiving antennas have far more modest requirements to reliably get signals from worldwide sources.