MINIMUF4.DOC, Version 4.1
July 26, 1986, by R. Dean Straw, N6BV
History of the Program:
Version 3.5 of MINIMUF.BAS was first found on the CompuServ Ham
Radio SIG about a year ago, and was customized at that time for
my use in the San Francisco Bay Area. It is my understanding
that the program was the result of the hard work of many people.
My modest contribution lies in the area of "fine tuning" it and
then compiling it for speed.
Version 4.1 presented here corrects some errors in the L/L of
several geographic areas (New Delhi and Bangkok).
This program will run on an IBM PC or equivalent clone, with no
less than 256K of RAM, preferably more, so that a print spooler
can be used to speed things up. Otherwise the limitation on
speed will be that of the printer.
The MINIMUF 3.5 program was tweaked repeatedly since I got it,
especially after I recently did an extensive study to compare the
program's "predictions" to actual results achieved during con-
tests in February and October (ARRL DX and CQWW contests.)
It was found that the bare-bones MINIMUF.BAS program tended to
forecast that the HF bands would open up about an hour earlier
than they actually did during a contest. The program was cor-
rected for this bias in a rather crude but effective manner by
shifting the matrix around by an hour. Then range and bearing
calculations were added to spice things up, and to give heed to
the warning when the original MINIMUF was published in September
1982 QST that distances greater than about 6000 miles (presumably
statute miles, but this could be nautical miles) might yield
inaccurate MUF results.
By the way, the stations used during these contests were first-
class contest stations, with large and high antenna arrays.
These stations consistently were able to open and close bands
ealier than most stations in the general geographic area, and
thus represent low-angle radiation conditions. The average "city
lot" station will probably find that the bands open somewhat
later than and close somewhat sooner than the program will calcu-
late.
Nevertheless, the MINIMUF4 program will give you a good clue of
when to be where in a contest situation, particularly during the
low sunspot cycle years, when higher frequency openings are brief
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and ephemeral, if indeed they occur at all.
Calling the Program:
First boot up your computer to show the DOS prompt and type
MINIMUF4, followed by hitting the <Enter> key. The program will
then prompt you for a name that it will subsequently use as a
label for the transmitting location. I, for example, type in:
San Francisco <Enter>. Don't try to enter: San Francisco, CA
<Enter>. MINIMUF4 isn't expecting a comma, and will give an
error message.
Next you will be prompted for your location's latitude and longi-
tude. These should be entered with a comma separating the lati-
tude and longitude, and you must convert minutes to decimal
portions of degrees: i.e., for 37 degrees 38 minutes North lati-
tude, 122 degrees 24 minutes West longitude, you would key in:
37.63,122.40 <Enter>, since 38 minutes is 38/60 = .63 degrees,
and 24 minutes is 24/60 = .40 degrees.
Accuracy down to this level is not really needed: your latitude
and longitude within a degree will yield results consistent with
amateur work!
You can then follow the prompts given for the rest of the infor-
mation the program requires. The Solar Flux numbers are general-
ly entered as the average of the last three days' worth of data
(plus today's SF number, making 4 days of data) from the WWV
transmissions at 18 minutes past the hour.
Comparisons to the charts published in QST each month are in-
structive. In general, the curves follow pretty well the QST
predictions, with perhaps an optimistic bias that tends to show a
somewhat higher MUF than QST does. This is actually useful for
contest preparation, since it alerts you to the possibility that
a higher band might be open, and you can plan to be there to try
things out and perhaps snag a QSO or two you might not have
gotten otherwise.
Note of course that the actual smoother Sunspot Number for a
particular contest period can be used, rather than using a pre-
diction of what the Sunspot Number is expected to be. QST has to
work under the burden of a two or three month publishing dead-
line, remember.
I would appreciate any comments you might have about this pro-
gram. Write:
R. Dean Straw, N6BV
5328 Fulton Street
San Francisco, CA 94121
2
Street
San