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DX Toolbox - Shortwave / Ham Radio / HF Radio Propagation

• Solar Flux: Indicator of solar activity. In general, the higher the number, the better HF and shortwave propagation conditions are, especially for the higher frequencies.
• Sun Spot Number (SSN): Another indicator of solar activity
• A Index: Daily average of geomagnetic conditions. The higher the number, the worse the HF conditions are.
• K Index: Three hour average of geomagnetic conditions. The higher the number, the worse the HF conditions are.
• Space weather conditions
• Whether any geomagnetic storms that might affect HF and shortwave propagation are in progress
• Whether any solar radiation storms that might affect HF and shortwave propagation are in progress
• Whether any radio blackouts affecting HF and shortwave propagation are in progess
• Current x-ray flux readings from the GOES-10 and GOES-12 satellites. The lower the readings, the better HF / shortwave propagation conditions are. Ranges are A1-A9,B1-B9,C1-C9,M1-M9,X1 and up. Low readings, especially in the A range, generally indicate good conditions. Higher readings can indicate poor conditions. Solar flares can cause readings to jump into the M and X range, which can cause radio blackouts for paths in the sunlit area.
• Solar wind conditions: Solar wind affects the Earth's magnetic fields, which in turn can effect HF and shortwave propagation.
• Geomagnetic field readings: Negative Bz readings can indicate auroral conditions are possible, which can adversely affect propagation over polar paths in particular. But you might get to see the northern or southern lights!

Solar and Geomagnetic Data Graph Window:

This window shows a graph of the last month's worth of readings for the solar flux, sunspot number, A index, K index, and background X-ray flux.

Periods of high and low solar activity usually repeat on a monthly basis. The monthly variation in solar activity can usually be seen, and it can be used as a quick visual indicator to see where we are in the current monthly cycle.



Propagation Prediction Map Window:

This window shows a map of the Earth, with the estimated signal levels on paths to all other parts of the Earth shown by the shading on the map. The lighter the shading, the stronger the estimated signal levels.

At the bottom, you can change several values which affect the calculations:

• The current time and date in UTC. Clicking the Current button will reset these. You can change the date and time to see what conditions would be like for another day and time.
• The frequency in MHz.
• The solar flux value. This defaults to the current value, but you can change to see the effect.
• Transmitter power in watts.

The titlebar of the window updates to show the latitude and longitude of the cursor, and the estimated signal level if the path is possible.

Grayline Map Window:

This is the traditional grayline map of the Earth. The daylit and nightime regions are shown by shading. This makes it easy to identify the grayline region, the terminator between day and night. Propagation conditions are often enhanced between locations on the grayline. So, what you do is observe what locations on the Earth fall on the grayline at the same time as when your location is there.

Another other useful tool in this window is the propagation path display. As you move the cursor around the map, a white line is drawn from your location to the location under the mouse cursor, showing the actual path the radio waves are likely to take. The bearing and path length are also indicated.

This window can also display in real time which NCDXF/IARU HF beacon is currently transmitting on any of the standard frequencies (14100, 18110, 21150, 24930, and 28200 kHz. The name and location of the beacon are shown, as well at the bearing and distance. If the path option is turned on, the path is drawn as well. You can then tune your receiver to that frequency, and as each beacon transmits (a new beacon transmits every 10 seconds, the entire cycle lasts three minutes), you can quickly determine the actual propagation conditions to that part of the world by observing how well the beacon is heard.

Each beacon transmission consists of the callsign of the beacon sent at 22 WPM morse code, followed by four one second dashes. The callsign and the first dash are sent at 100 watts. The remaining dashes are sent at 10 watts, 1 watt and 0.1 watts respectively.



Propagation Path Estimation Window:

This window lets you specify two locations (usually yours and the target) as well as the frequency, solar flux, transmitter power level, and date. It then calculates the estimated signal level for each hour of the day, so you can see at what hours of the day the path is open on that band.

You can create and store a list of locations by name, longitude, and latitude, and then call them up using the popup menus for the Location A and Location B.



Propagation Path For Time Estimation Window:

This window lets you specify two locations (usually yours and the target) as well as the solar flux, transmitter power level, time, and date. It then calculates the estimated signal level for each frequency, from 0 to 40 MHz, so you can see over what frequencies the path is open on that band.

You can create and store a list of locations by name, longitude, and latitude, and then call them up using the popup menus for the Location A and Location B.



MUF / LUF Estimation Window:

This window lets you specify two locations (usually yours and the target) as well as the solar flux, transmitter power level, and date. It then calculates the estimated signal level for each hour of the day, and for each frequency between 0 and 40 MHz, and generates a color coded graph showing the estimated signal level at each hour for the range of frequencies where propagation may be possible.

You can create and store a list of locations by name, longitude, and latitude, and then call them up using the popup menus for the Location A and Location B.



Reports Window:

This window will automatically download and display 20 different propagation reports, notices, warnings, and forecasts. The following reports are available:

The shockwave from a CME (coronal mass ejection) can be seen as a sudden increase in the solar wind speed, and often will cause poor shortwave propagation conditions to begin, especially if the Earth's Bz magnetic field happens to be negative at the time of impact.



GOES X-Ray Flux Graph:

This is a graph showing the most recent three days worth of x-ray flux data from the GOES-10 and GOES-12 satellites. Solar flares cause a sudden increase in x-ray flux levels. This in turn can result in much stronger absorption of shortwave radio waves by the ionosphere, causing much lower signal levels, and in some cases complete radio blackouts. Lower frequencies are usually affected first, and most severely.

Solar flux levels are on a logarithmic scale, with A1 being the lowest level, rising to A9 and then B1 (which would be like A10) to B9, C1 to C9, M1 to M9, and then X1 and up, with no upper limit. Background levels are usually in the A or B range, sometimes in the C range when the Sun is very active. Flares can cause levels to rise to the M or even X levels.

Conditions are generally best (quiet) when x-ray flux levels are lower. Large M and X class flares can cause HF radio backouts for paths that cross over the daytime region of the Earth.



GOES X-Ray Flux Graph:

This window is the same as the one above, except that only previous 6 hours are displayed, giving a better picture of very recent solar activity.