I've been asked by a few people how I tell when it's a good time to monitor HF.
Here's a quick reference tutorial. Hopefully Mike can make this a sticky.
Here's a simple way to understand HF propagation:
1. K-Index -- the higher this value (0-9) the worse HF will sound -- from no impact to minor fade to fluttery signals to zero signal.
2. Solar flux (SN) -- the sunspot number is what determines the overall band conditions. The higher the number the better the propagation of HF (especially the upper HF bands.)
3. X-Ray -- (integrated into the K-Index) but this value is what determines the severity of the absorption of HF radio signals. The class range is from A/B, C, M and X. Large X-Class solar flares are the least desirable.
4. WWV/CHU -- the time beacons are great for checking propagation. The usual North American time beacons are: 2.5 Mhz, 3.330 Mhz, 5 Mhz, 7.850 Mhz, 10 Mhz, 14670 Khz, 15 Mhz and 20 Mhz in AM mode.
5. RWM -- The time beacon from Moscow, Russia transmits on 9996 and 14996 Khz in CW mode. If you can hear/see RWM then you know you have good propagation!
One point that is confusing to some people is that while conditions are "bad" this doesn't mean you won't hear stations. It just means that the signals could be weak, have poor audio and/or a combination of both. Usually the strong stations (aka SW Broadcast) will still be heard but their audio quality could be affected.
Usually, the bad HF conditions will generally mean improved VHF conditions from 6m to 2m because the ionosphere is in an excited state. This is why 11m (CB) and 10m (HAM) will become very active during these "bad" HF periods.
A couple of great web sites to check:
SpaceWeather.com -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids
HF Propagation and Solar-Terrestrial Data Website
Here's a quick reference tutorial. Hopefully Mike can make this a sticky.
Here's a simple way to understand HF propagation:
1. K-Index -- the higher this value (0-9) the worse HF will sound -- from no impact to minor fade to fluttery signals to zero signal.
2. Solar flux (SN) -- the sunspot number is what determines the overall band conditions. The higher the number the better the propagation of HF (especially the upper HF bands.)
3. X-Ray -- (integrated into the K-Index) but this value is what determines the severity of the absorption of HF radio signals. The class range is from A/B, C, M and X. Large X-Class solar flares are the least desirable.
4. WWV/CHU -- the time beacons are great for checking propagation. The usual North American time beacons are: 2.5 Mhz, 3.330 Mhz, 5 Mhz, 7.850 Mhz, 10 Mhz, 14670 Khz, 15 Mhz and 20 Mhz in AM mode.
5. RWM -- The time beacon from Moscow, Russia transmits on 9996 and 14996 Khz in CW mode. If you can hear/see RWM then you know you have good propagation!
One point that is confusing to some people is that while conditions are "bad" this doesn't mean you won't hear stations. It just means that the signals could be weak, have poor audio and/or a combination of both. Usually the strong stations (aka SW Broadcast) will still be heard but their audio quality could be affected.
Usually, the bad HF conditions will generally mean improved VHF conditions from 6m to 2m because the ionosphere is in an excited state. This is why 11m (CB) and 10m (HAM) will become very active during these "bad" HF periods.
A couple of great web sites to check:
SpaceWeather.com -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids
HF Propagation and Solar-Terrestrial Data Website
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