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Ionospheric propagation Ionosphere Ionospheric layers Skywaves & skip Critical frequency, MUF, LUF & OWF How to use ionospheric propagation Multiple reflections & hops Ionospheric absorption Signal fading Solar indices Propagation software NVIS Transequatorial propagation Grey line propagation Sporadic E Spread F
As electromagnetic waves, and in this case, radio signals travel, they interact with objects and the media in which they travel. As they do this the radio signals can be reflected, refracted or diffracted. These interactions cause the radio signals to change direction, and to reach areas which would not be possible if the radio signals travelled in a direct line.
While it is possible to gain an idea of what HF radio propagation conditions may be like, and what the likelihood of establishing a particular radio communications link may be, purely from a general knowledge of HF radio propagation and a knowledge of the solar indices. However for a more exact analysis of the possibility of establishing two way radio communications, mobile communications, or for assessing broadcast coverage it is necessary to undertake a more rigorous and mathematical approach. This lends itself very well to a computer and software orientated approach.
There are very many radio propagation prediction software packages that are available. Many of these radio propagation prediction software packages have been developed over many years. Some were developed for broadcasters, while others were developed for military applications. With the reduction in the use of the HF bands for military and broadcast applications many of these software packages have been released for free use or for purchase at a minimal cost. This has considerably widened the use of these packages which are now within the reach of many radio communications users.
This radio propagation prediction software can now be freely used by all manner of radio users including two way radio communications applications, maritime mobile radio communications, radio broadcasters (small and large), point to point radio applications, radio amateurs, etc. In this way all these users are able to choose the optimum frequencies and times of day to establish their radio communications link, or to broadcast to a particular area with a far greater degree of certainty of being able to successfully achieve their goal.
Radio propagation prediction software
Radio propagation prediction software uses many factors to determine the statistical probability of a particular path being open. Built in to the programme there is always a considerable amount of data that has been gained over many years of research. Items such as the time of day, the variations of HF propagation that are experienced over different areas of the globe. The season and time of day also have significant impacts of the radio propagation prediction as well..
In addition to these various other inputs are required to enable the radio propagation predictions to be made. The indicators of the level of solar radiation and geomagnetic activity are also needed. These may be required in various forms but they can generally be obtained from a variety of sources on the Internet. These need to be entered along with the required path or coverage area needed and obviously the location of the transmitter.
Radio propagation prediction software packages
There is a large variety of radio propagation software packages that have been developed. Many are very sophisticated and have been developed over many years. These radio propagation software packages are used by all users of the HF radio communications from broadcasters who need to know the likely coverage areas for their radio transmissions and other professionals radio communications users who need to be able to know which frequencies to use to establish a link to a given area to radio amateurs.
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