The prediction engine used to construct these maps is the latest offering from the ITU, ITURHFProp, freely available from https://www.itu.int/en/ITU-R/study-groups/rsg3/Pages/iono-tropo-spheric.aspx.
As a base we use central U.K., thus creating a world-wide propagation view suitable for everyone in the U.K.
The plots are recalculated at the beginning of each month. A choice of frequency, reliability (REL), signal-to-noise ratio (SNR) or field strength (S-Meter) are available at the bottom of the plot under "Band:" and "Type:".
Along the right hand side is the colour legend, percentage for REL, dB for SNR and (S-Meter) for field strength.
A day/night terminator line is shown for convenience.
To use these plots, choose the frequency of interest, then look at the plots in any order. For example, for propagation to the Ivory Coast on 14MHz at 14:00 UTC the S-Meter plot may suggest S2, an SNR of between 10 and 20dB and finally a reliability of between 60 and 70%. What does this mean? The SNR is low, but for good quality receivers and keen ears it is workable for CW; but for SSB, a higher SNR is needed. The stated reliability will occur on at most 70% of days this month and the expected S-Meter of 2 may be below local noise levels. Only those with a quiet noise background could realistically be expected to communicate during this particular period with the stated power level and aerial type.
To reiterate, it is important to consider both the SNR and REL for each of the parts of the world of interest. A REL of 50% is also necessary for day to day working.
There are two ways whereby the Transmit and Receive sites can be established: (i) move the map pointers to the desired locations and (ii) entering the required co-ordinates in the script boxes. South and West are negative(-).
Click in the 'Date' box and a drop down will appear for the month/year selection. If the box is left empty, it defaults to the current month.
Choose the aerial type for both Tx. and Rx. sites.
Enter the required Tx. power in watts. The upper limit for this application is 1000000 watts.
Choose the 'Mode', 'Path', and 'Background Noise' for the required predictions.
Finally, click the 'Generate Prediction' button.
A spinner will appear advising that the predictions are being prepared.
The four headers at the top of the page will become available. 'MUF + SNR', 'MUF + Reliability', 'MUF + Medium Rx. Power' and 'ITURHFProp Output'. Just like the Area Coverage plots all three of the plot types should be studied. The same interpreting rules apply. Hovering the mouse inside the plot gives static information.
Some enhancements have been added to aid understanding, i.e. a simple legend at the bottom of each page. And more importantly a choice of colour scheme for the plots, this allows those with a colour preference to choose the one that suits them the best.
At the bottom of the 'Medium Rx. Power' plot the user will find a graph which at first glance looks confusing. However, to make it much clearer it is possible to click (on the right side legend) a particular frequency to make that line disappear, click it again and it reappears. Also hovering the mouse on the graph shows all the details.
There is now a special feature; the URL will be populated with details of a prediction. Sending this URL in the body of an E-mail will enable the receier to see the same prediction output.
When the choice of output from the front page is 'FT8', the 'Medium Rx. Power' shows the predictions below that readable for say say CW. It goes down to the accepted FT8 receive floor of -24dB.
The last item 'ITURHFProp Output' shows the textual output from the program.
Both of these little applications are either self explanatory or have an explanation on the page, therefore no further instructions need be added here.
This application requires very little explanation as the instructions are shown at the top of the page. Fill out the Lat/Long either by typing in the co-ordinates of interest or by using the flag markers.
The output at the end is also rather easy to follow. It was designed as a quick guide to facilitate the time used up to calculate these parameters.
Following requests from users at various locations, it was decided to produce an 'Area' coverage scheme that everyone could use.
Once more this application is self explanatory, merely fill out the form and click 'Generate Area Prediction'. The output will appear with the same plot choice as the P2P predictions.
Please note these plots are resource hungry and will take about 50 seconds to complete, so please be patient.
When doing comparisons, it is suggested that the plots are saved locally, as they will be deleted from the server to retain disk capacity.
Any comments/suggestions e-mail Gwyn Williams, G4FKH - email@example.com.