Historical notes on development of K1TTT-MOF algorithms. History: About 1987 Start from MINIMUF85 formulas. These have many obvious shortfalls due to the limited dataset they were derived from. They were derived and tested for a relatively small set of data. The MINIMUF85 update to MINIMUF3.5 was done by curve fits to observed MUF data over several paths and by adding fudge factors into the original model equations. This seemed to obscure the meaning of several of them since the fudge factors started to override the original meaning of the formulas. My original work on my old MUF prediction program was essentially just basic groundwork for getting the program working. I developed the world maps for MUF/LUF display, the method for viewing intermediate calculations, and the basics of comparing(manually) a prediction with an actual contest log. I adapt a LUF program from a SW broadcast predictor for the lower frequency bands. 1991 or so After adding my own adjustments to the MUF fudge factors I decide that the model has been pushed to its limit. Its time to rip out some of the old stuff and replace with cleaned up equations and some different physical models. My MUF program is put on the shelf and converted to MOF. Detailed reading and thought on the prediction of band openings for contest operations has shown that the MUF model just isn't useful for what we need. It appears from studying several contests and comparing to the MINIMUF model and other programs that predict MUF using other methods that we are often operating well above the predicted MUF. Granted, signal are weak, and by the classic definition of MUF we could not pass traffic reliably or meet a minimum signal strength measurement, but we can make contact and exchange contest data. It becomes obvious that we are actually operating near the MOF, the Maximum Observed Frequency, that can be up to 50% higher than the MUF. Thus I take that name for my program. The same applies for the Lowest Observed Frequency, although this seems less common in the literature. I have been studying the sections of the book "Ionospheric Radio" by Kenneth Davies that draws heavily on the works of others to present an overview of radio wave propagation through the Ionosphere. Refer to the the MOFCALCS.TXT file for the details of how the parts fit together, but basically these are the major changes I mad to arrive at the MOF model. 1. While the shape of the critical frequency plot seemed reasonable the absolute values of the max and min were way off. I did extensive curve fitting of data taken from plots of the noon time critical frequencies at Washington DC (Ionospheric Radio pgs 134-135) vs sunspot numbers from 1947 to 1986. My analysis showed the same basic shape as Davies develops on pg 136 for the maximum values. I also develop a fit for the annual variations to account for the "Winter Anomaly" he discusses starting on page 135. These are put into the g2a (f0F2) model to properly scale the ranges of critical frequency. 2. I add an option to use the 'real' magnetic dip values from Davies pg 44 world map vs the simplistic magnetic lat/lon formulas in the MINIMUF algorithms. 3. The 'Control Point' selection in MIMIMUF was tailored mostly to mid-range paths, pretty much 2000-6000km if I remember correctly. Much beyond those ranges and it seemed to fall apart. I generalized the algorithm to more evenly distribute the Ionospheric Reflection Points along the path. While this slowed the calculations by adding more points in most cases the predictions seemed much better and adjustments to the critical frequency produced more predictable changes since it is sampled at regular intervals along the path. 4. A less obvious problem was the MINIMUF calculation of the Ionosphere height used to figure hop lengths and reflection angles. I did some work to make sure that the results fell in a reasonable range based on Davies Chapter 5 summaries of height changes due to Sunspot numbers, diurnal and annual variations, but more work needs to be done on this area. I also need to take a better look at how to handle paths where the height of the ionosphere changes drastically, the "tilted" ionosphere problem as discussed in Davies page 182 with respect to trans-equatorial paths. Starting abt 1992: Ok, all those formulas are nice, but predictions still not real good when compared to contest data. Now I develop method to 'score' the comparison of the prediction with an actual contest log. This takes the actual contacts from a weekend and calculates percentages of the actual paths worked that were at, above, or below, the predicted MOF for that path. I play with that for a while and determine that there are too many constants to test each one manually... especially since after changing one I have to recompile the program. Now I develope the constant 'diddle' process. This lets the program change each constant up and down a given percentage, recalculate the prediction, rescore against the reference log data, and record change in a log file. A complete run takes 36-48hrs on a 386dx-24(with 387 coprocessor), the first few runs show the really weak areas in the formulas, some minor adjustments raise predictions from 30-40% 'at' value to 50-70%. I err on the optimistic side so that only 10-15% of the time we work paths that are above the predicted MOF, many of these are near the edges of the predictions, or could be accounted for by skew paths. 1994: Offer program on Internet contest reflector in return for contest logs. Most logs received just confirm that prediction is reasonable. Analysis of low flux logs from WPX and ARRL tests shows some weaknesses in the Transequatorial paths and maybe an over optimistic prediction for 10 and 15m on high lattitude paths. But after several attempts to 'diddle' constants again only minor (2-5%) improvements can be made. The TE path algorithm needs changing, I note that the constants had been changed in the last analysis to eliminate this correction... a good sign that it was wrong then also. Maybe in the high flux situations the TE correction was masked by other factors, but in low flux it is more important. A windows version is under development, the equations are all the same, just the presentation is different. 1995 Windows version working, lots of changes. Calculations common between Dos and Windows versions but interface all different. 1996 Add better analysis features to windows version. Add A/K geomagnetic activity indices to calculations. Do lots of adjustments to constants. Add report for comparison of lots of logs at once, plot results with MathCAD to find weak points.