To start the program, double-click on the program Icon. A large selection window will appear for you to input the specifics for the propagation chart you wish to plot.
1.1 Set up your home location Default information
Set up the difference between Local and UTC/GMT by entering clicking on the Defaults button. The Default values for the Sun Spot Number can also be
reset from 100.
Then set up your home location. Click on "Change Buttons". You may select any button to reconfigure. I use the QTH (Ham jargon meaning "location") button on the bottom right.
Both settings are remembered by the program each time the program is run when you return to the Main Menu.
1.2 Location Selection
The MUF and LUF between any two (of forty) different locations may be selected by clicking on the appropriate Location buttons. The "From" and "To" locations will be displayed immediately below the button area. Location buttons are User Customizable (see below).
1.2 Date
The default date is the Macintosh system date. A different month or day may be selected by clicking on the Up and Down buttons in the Month or Day box. This is useful in determining what propagation will be like in a month or two, or, for example, seeing the seasonal differences between the summer and winter solstice and the spring or summer equinox.
1.3 Sun Spot Number
Sun spot numbers (and average ranges for each month) are published in QST magazine (published by the Amateur Radio organization - the ARRL, Newington, Connecticut).
Also, the solar flux level is announced at 18 minutes past every hour on WWV, transmitted on 10, and 15 Mhz (and other frequencies) by the Bureau of Standards. A special reference chart is currently required to convert solar flux to sunspot numbers, required by MacSW. Future versions of this program may support direct input of Solar Flux values.
1.4 Display Chart
Once the locations and other values have been selected, a chart of the LUF and MUF can be displayed by clicking on the Display Chart button. The Chart Display Window will appear and the MUF line (top) and LUF (bottom) line will immediately begin to plot for every half hour of the day.
Generally speaking, the higher the MUF the better the propagation on the higher short wave frequencies. Also, the lower the LUF during periods of high MUF, the better the propagation.
The distance (in miles) and angle (beam heading) between the two locations is also displayed.
1.4 Displaying Several Charts
By clicking the previous chart button, the previous charts' MUF/LUF data will be displayed. The last 20 charts are remembered (from the time the program was launched).
This feature is particularly useful for comparing propagation between two locations for each of several months, or for comparing propagation from your location to several different locations on the same chart.
2. More on Changing Buttons
Location and Latitude/Longitude of any (or all) locations may be customized by the User. To enter changes, click on the Change Buttons button and a window of all location buttons will appear on the screen. Click on the button you wish to change. An edit window will appear which allows a new location name, latitude, and longitude to be entered. Click on OK to complete the button edit. Additional buttons may be edited from this window. When the editing is completed, return to the main window. The new values are remembered within the program.
3. General Theory
3.1 Shortwave Radio and the Ionosphere
Mac ShortWave is a radio transmission propagation prediction program.
Long-range shortwave radio communication normally occurs when radio signals (from 1.5 to 30 Megahertz) are bounced back to earth by a layer of ions which form (you guessed it) the ionosphere (about 150 miles above the earth's surface). These ions emanate from the sun and the amount of ionization depends on the 11 year solar Sun Spot cycle, rotation of the sun, solar flares, etc.
3.2 Maximum and Lowest Usable Frequencies
Successful shortwave communications between two points depends on the condition of the ionosphere, Ie., the ionosphere's ability to bounce or refract radio signals back to earth. The refractive properties of ionosphere between any two locations varies over the range of shortwave frequencies.
Successful communications are normally achieved within a range of frequencies referred to as the Maximum Usable Frequency (MUF) and Lowest Usable Frequency (LUF). The condition of the ionosphere (Ie. the LUF and MUF) varies considerably depending on the time of day and other factors including calendar date and solar activity. Mac ShortWave will produce a graph of the LUF and MUF for any two points on the earth throughout a 24 hour period.
Example: From 0700 to 0800 local time, the LUF and MUF for the Dallas to London path are 13 Mhz and 31 Mhz., respectively. That means I should be able to hear English shortwave stations on the 21.7 Mhz (13 Meter) band, whereas reception on 12 Mhz may not be attainable.
MacSW also maintains a record of each graph displayed so the user can compare the differences between test graphs for various locations, dates, and sun spot levels.
As you would expect, Mac Shortwave propagation prediction requires several user inputs:
• Time and Date
Calendar Date is an important factor. The date determines the angle of the earth's axis relative to the sun. Obviously, the time of day also effects this angle. The angle of the earth's surface (and ionosphere) relative to the sun, determine how ions are retained and ultimately form a refractive surface in the ionosphere for shortwave radio signals.
• Sun Spot Number
The number of sun spots on the surface of the sun determines the amount of ions being given off from the sun. These ions eventually reach the earth, and settle into bands or layers in the earth's ionosphere that are responsible for refracting short wave radio signals back to earth. MacSW calculates the "F" layer and "E" layer effects.
• Location Latitude and Longitude
Latitude and Longitude values are used to specify the locations for which shortwave propagation is being checked.
4. Comments and Bug Reports
Your comments, ideas, suggestions, problem reports, etc. are appreciated. Please send to:
CIS 71460,1610
AOL N2BXA
(or below).
I check my E-mail at least weekly.
5. Shareware Fee and Registration
Mac ShortWave Ver. 1.2 is copyright December 19,1991,
by Ed Neubauer (formerly BXA Research).
Please register by sending your $12.00 Shareware fee to:
