                                        1 Jan 2017
Hello,

PROP7R5 is a Microsoft DOS program that runs on Microsoft Windows versions up through Windows XP. While DOS programs are no longer supported on Windows Vista or later, PROP7R5 can be run on these later versions of Windows using the Dos emulator "DosBox" (see www.dosbox.com). There are versions of DosBox for Mac OSx and Linux as well.

This program was developed beginning about 1989 based on the 1985 and 1987 IONPRED and COMB7B programs published by Raymond Fricker of the BBC as provided to me by Bob Brown, NM7M. Dr. Brown encouraged my further development of the prediction methods and algorithms. This version dates from 1999 with relatively minor changes since.

I hope you will find the program self-explanatory.  Once you enter your latitude and longitude the first time, the program will ask if you wish these values to be stored on disk for later recall.  Most of the questions can be answered with an "enter", to get a default value.  You can experiment to see what these defaults are.  The default values for the date questions are the current date contained in the system clock (DOS/BIOS DATE). The lat and long for the RX location can be found from Google Maps or from many online sources. A simple text file, QTH.fil, is provided with this program that lists the coordinates for many DX prefixes. The first few times you run the path predictions, I suggest you answer “n” to the question re. “Do you want to stop the display when the screen is full?”. The screen displays will show how the program searches for viable path modes.

PROP7R5 automatically searches for paths beginning at the lowest possible angle until a path supporting propagation is found up to a user defined maximum. On the lower frequencies the search continues (up to 30 degrees on 160 metres, 20 degrees on 80 metres) at elevation angles higher than the lowest viable path found since higher signal strengths sometimes occur at angles higher than the lowest angle providing a path.

There are several types of path prediction options. The zone method was developed because the conventional ray tracing method failed to predict low band openings that were observed from Victoria, especially for longpath. The zone method predictions correspond better to the actual observed openings from Victoria.  The skew path option is a modification of the
zone method.  This shows when off-great-circle headings may occur that provide reflection into a very low angle.  This occurs mainly below 7 MHz, and this option provides the closest correspondence to the openings that I observe on 1.8 MHz.  (There are off-great-circle heading paths on 14 MHz that the program does not currently predict, apparently because a different mechanism is responsible for these paths.)  

All options automatically search for "ducting" type paths involving reflections between the E and F ionosphere layers without intervening ground reflections. Including this ducting type of propagation mode resulted in dramatically improved correspondence between predicted and observed openings on 1.8 and 3.5 MHz.  Lowband longpath and grayline propagation is best predicted using the zone and skew options, while more conventional
paths on 14 MHz and above are well handled by the ray tracing options. The zone method predictions should be viewed as indicating possible times and modes of openings, not that openings should be expected during all of the indicated times.  I have found that actual lowband openings have, with few exceptions, occurred when the zone method indicated a possible opening.


The program currently has no means to adjust for variations in absorption (cf., the WWV "K index" values), nor for polar cap ionospheric disruptions.  The predictions are in some sense "best case" predictions.  The values give a good correspondence to what I hear on the "good days".  You can get some indication of the likelihood of seeing the predicted strengths from the "percent of days" figures.  Use the WWV (e.g., 10 MHz) "solar flux"
values (given at 18 and 45 minutes after the hour) for the value of solar flux requested by the program.

There MAY be propagation when the program predicts none, but these openings are generally of the shortlived,low strength, fluctuating, unreliable sort.  Signals from locations
near the antipode, however, may travel paths other than the one this program checks and could be quite strong.

I find the program is useful for telling me what time to look for propagation between two places on a particular band, for sunrise/sunset times, for finding grayline openings, and also for making skeds.

I would appreciate your comments on how it could be improved, and how you have used it.

73,
Roger Graves
VE7VV (ex VE7FPT)
