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MINIPROP (TM) Ionospheric Propagation Predictions Version 2.0 A User-Supported Program Copyright 1985, 1987 by Sheldon C. Shallon, W6EL Protected by Federal Copyright Law. Permission granted for non-commercial use and distribution. Not to be used for commercial advantage. All rights reserved. This document contains 34 pages. TABLE OF CONTENTS 1. Introduction 4 Background 4 Fundamentals of Ionospheric Propagation 5 Disclaimer 7 Distribution and Use of MINIPROP 8 2. Starting MINIPROP 9 3. The Master Menu 10 4. Running a MINIPROP Prediction (Master Menu Choice 1) 11 Latitudes and Longitudes 11 Entering Terminal A Data 12 Entering Terminal B Data 13 Entering the Date 13 Entering the Sunspot Number or Solar Flux 13 An Example 14 The Command Line 19 5. DX Compass (Master Menu Choice 2) 21 Entering Data 21 An Example 21 6. Changing Prediction Parameters (Master Menu Choice 3) 23 Change Frequencies Used in Signal Level Predictions 23 Change Antenna Minimum Radiation Angle Used in Predictions 24 Suppress Output of Low Signal Levels 25 Suppress Output of Signal Levels at Frequencies Higher than Predicted FMUF 25 Change Path (Short or Long) to be Computed First 26 Restore Original Set of MINIPROP Defaults 26 7. MINIPROP Utilities (Master Menu Choice 4) 28 8. Create or Modify Terminal A Default (MINIPROP Utilities Choice 2) 28 9. Display Entries in MINIPROP Atlas (MINIPROP Utilities Choice 3) 29 10. Add, Modify or Delete Entry in MINIPROP Atlas (MINIPROP Utilities Choice 4) 29 Adding an Atlas Entry 29 Modifying an Atlas Entry 30 Deleting an Atlas Entry 30 11. Display MINIPROP Documentation on Screen (MINIPROP Utilities Choice 5) 30 12. Send MINIPROP Documentation to Printer (MINIPROP Utilities Choice 6) 31 -2- Table of Contents 13. Print Table of Great-Circle Bearings (MINIPROP Utilities Choice 7) 31 14. Convert Version 1 MINIPROP.ATL to Version 2 MP.ATL (MINIPROP Utilities Choice 8) 32 15. References 33 -3- 1. Introduction --------------- MINIPROP is a program for predicting ionospheric (skywave) propagation on frequencies between 3 and 30 MHz. Background ---------- I wrote my first propagation prediction program in 1966 to help me work DX. That first program, a computerized version of the cook-book procedure in NBS Circular 462 (1), was written in BASIC on a GE time-sharing computer. During the next several years the program was revised several times to take advantage of improved prediction algorithms contained in several government publications, primarily NBS Monograph 80 (2), ESSA Technical Report ITSA-1 (3), and ESSA Technical Report ERL 110-ITS 78 (4). Additional information was obtained through personal correspondence with one of the authors of ERL 110- ITS-78. Additional program versions were written in BASIC for several computers, and versions were written in FORTRAN and RPN. All of these programs predicted only signal strength. MUF was predicted manually, using the two-control-point method with a control point near each end of the path, from world maps with superimposed predicted iso-MUF(ZERO)F2 and iso-MUF(4000)F2 curves (5)(6). In December, 1982, MINIMUF-3.5 (7)(8), developed by the U.S. Naval Ocean Systems Center, appeared in QST (9). Although it used an incorrect algorithm for control points that are in midnight sun conditions (10)(11) and for some control points that are in polar night conditions, MINIMUF made practical the prediction of F-layer MUF on microcomputers. MINIPROP version 1, released August 19, 1985, for CP/M computers, combined the prediction of signal levels, F-layer MUF (using an improvement on the MINIMUF-3.5 model with corrections for the midnight sun and polar night conditions), and E-layer cutoff frequency. The MS-DOS version was released the following October. MINIPROP was a compiled program written in the Pascal programming language. MINIPROP was the most comprehensive propagation prediction program for microcomputers that was available to the radio amateur, and copies of version 1 spread quickly worldwide. As usage expanded, an increasing number of requests were made for additional features. At the same time, improved ionospheric propagation models were acquired from several sources. In particular, a superior F-layer model (12) and other prediction techniques (13) used by the BBC were made available through published literature and personal correspondence, and an improved method for predicting E-layer cutoff frequency was obtained from a report of the ITU International Radio Consultative Committee (CCIR) (14). The additional features and improved propagation models have been combined in version 2 of MINIPROP. The improved models are more complex than those in the original MINIPROP and so have a longer running time, but the additional time is well worth the improved prediction accuracy. -4- Fundamentals of Ionospheric Propagation --------------------------------------- The ionosphere is that region of the earth's atmosphere in which free ions and electrons exist in sufficient abundance to affect the properties of electromagnetic waves that are propagated within and through it. Ions are produced in the atmosphere partly by cosmic rays but mostly by solar radiation. The latter include ultraviolet light, x rays, and particle radiation (during storm periods). These radiations are selectively absorbed by the several gaseous constituents of the atmosphere, ion-electron pairs being produced in the process. For practical purposes, the ionosphere can usually be assumed to extend from about 50 to roughly 2000 km above the earth's surface. The structure of the ionosphere is highly variable, and this variability is imparted onto signals propagated via the ionosphere. The ionosphere is divided into three vertical regions -- D, E, and F -- which increase in altitude and in electron density. The D region has an altitude range from 50 to 90 km. The electron density in the region has large diurnal variations highly dependent upon solar zenith angle. The electron density is maximum near local noon, is higher in summer than in winter, and is lowest at night. The E region spans the altitude range from about 90 to 130 km. The maximum density occurs near 100 km, although this height varies with local time. The diurnal and seasonal variations of electron density are similar to those of the D region. Collisions between electrons and neutral particles, while important in the E region, are not as numerous as in the D region. The E region acts principally as a reflector of hf waves, particularly during daylight hours. Embedded within the E region is the so-called sporadic-E layer. This layer is an anomalous ionization layer that assumes different forms -- irregular and patchy, smooth and disklike -- and has little direct bearing to solar radiation. The causes of sporadic-E ionization are not fully known. The properties of the sporadic-E layer vary substantially with location and are markedly different at equatorial, temperate, and high latitudes. "Short-skip" openings, sometimes on an otherwise dead band, are often a result of one-hop sporadic-E ionization. When sporadic-E ionization is sufficiently widespread, multi-hop propagation is possible. MINIPROP predictions do not include the effects of sporadic-E ionization. The highest ionospheric region is termed the F region. The lower part of the F region, from 130 to 200 km, is termed the F1 region, and the part above 200 km is termed the F2 region. The F2 region is the highest ionospheric region, usually has the highest electron density, and is the region of greatest value in long-distance hf ionospheric propagation. The region exhibits large variability in both time and space in response to neutral winds and electrodynamic drifts in the presence of the earth's magnetic field. The maximum electron density generally occurs well after noon, sometimes in the evening hours. The height of the maximum ranges from 250 to 350 km at midlatitudes to 350 to 500 km at equatorial latitudes. At midlatitudes, the height of the maximum electron density is higher at night than in the daytime. At equatorial latitudes, the opposite behavior occurs. -5- The F1 region, like the E region, is under strong solar control. It reaches a maximum ionization level about one hour after local noon. At night and during the winter the F1 and F2 regions merge and are termed simply "F region". Electromagnetic waves are refracted when passing through an ionized medium, the refraction increasing with increased electron density and decreasing with increase of frequency. If the refraction is large enough, a wave reaching the ionosphere is bent back toward earth as though it had been reflected, thereby permitting reception of the wave at a large distance from the transmitter. The F2 layer is the most important in this regard because of its height and its high electron density. The maximum earth distance traversed in one F2-layer "hop" is about 4000 km. Round-the-world communication can occur via multiple hops. If the frequency is too high, the wave is not refracted sufficiently to return to earth. The maximum frequency for which a wave will propagate between two points is called the maximum usable frequency (MUF). Frequencies higher than the existing MUF at any given time are not supported, no matter how much power is used. However, because of the large variability that exists in the electron density of the F2 region, predicted MUFs are not absolute limits, but are statistical in nature. The actual MUF at any given time may be higher or lower than the predicted MUF. Predicted MUFs are intended to be median values; i.e., the actual MUF will exceed the predicted MUF 50 percent of the time, and will be less than the predicted FMUF 50 percent of the time. The predicted frequency that will be supported only 10 percent of the time is a frequency higher than the predicted MUF called the highest probable frequency (HPF), but even higher frequencies are possible 10 percent of the time. The predicted frequency that will be supported 90 percent of the time is a frequency lower than the predicted MUF called the optimum traffic frequency (FOT). Curves of predicted HPF, MUF, and FOT for several paths appear each month in QST. In MINIPROP, the predicted F2-layer maximum usable frequency is referred to as FMUF. Signals on their way to or from the F2 layer must pass through the E region of the ionosphere. The E layer is also capable of "reflecting" hf signals, and if the E-layer MUF is too high, the signals to or from the F2 layer are blocked -- or cut off -- by the E layer. In MINIPROP, the E-layer cutoff frequency is referred to as ECOF. Signals at frequencies below the ECOF will not pass through the E layer. Signals can propagate between two points on earth via the E layer in the same manner as they do via the F2 layer, but the maximum earth distance traversed in one E-layer hop is only about 2000 km, so a significantly greater number of hops is usually required on DX paths. E-layer propagation modes are not predicted by MINIPROP. The D region of the ionosphere must be traversed by signals on their way to and from the F2 or E layers. Electron densities in the D region are not large enough to cause hf signals to be returned to earth, but the high collision frequency between the electrons and neutral particles in the D region gives rise to absorption of signals passing through it. The reduction of signal strength can be substantial, particularly in daytime on the lower hf frequencies. Antenna installations that provide low radiation (take-off) angles can minimize the number of hops required between two stations, thereby reducing the number of passes through the D region and the amount of signal absorption. -6- Electron density in the ionosphere increases with increased solar activity. Therefore, MUFs and signal absorption both increase as solar activity increases. The Zurich smoothed mean sunspot number has been used extensively as an index of solar activity and the one with which propagation data has been correlated over the years. Therefore, most propagation prediction models require that the user specify the sunspot number to be used in making a prediction. The 2800-MHz (10.7-cm) solar noise flux is generally considered a more accurate measure of solar activity, but with a smaller base of propagation observations. Since the two indices are highly correlated, either index may be used. MINIPROP allows you to specify either sunspot number or solar flux as a measure of solar activity. Ionospheric propagation is susceptible to several kinds of short-term disturbance that are usually associated with solar flares. Depending upon the nature of the disturbance, they are called sudden ionospheric disturbances, polar cap absorption events, or ionospheric storms. These disturbances upset the electron configuration in the ionosphere, and consequently affect propagation. Propagation is also affected by changes in the earth's magnetic field. The magnetic field is constantly fluctuating, but the fluctuation occurs over much wider limits during magnetic storms that accompany ionospheric storms. Ionospheric and magnetic storms are also often accompanied by visible aurora. Except for the tendency of these disturbances to recur in synchronism with the 27-day rotation period of the sun, they are difficult for the amateur (as well as the professional) to predict and to quantify. The severity of magnetic disturbances is indicated by A and K indices that are broadcast by WWV at 18 minutes past each hour. The A index is a daily measure of geomagnetic field activity on a scale of 0 to 400. The K index is a measure, for a 3-hour period, of variation or disturbance in the geomagnetic field on a scale of 0 to 9. In general, MUFs decrease and signal absorption increases as geomagnetic field activity increases, although MUFs sometimes increase in equatorial regions. Propagation only along great-circle paths is considered in MINIPROP. Backscatter modes and bent-path modes are not considered. More information about ionospheric propagation can be found in "The Shortwave Propagation Handbook" by W3ASK and N4XX (15), and in Chapter 22 of the "The 1987 ARRL Handbook" (16). Disclaimer ---------- Sheldon C. Shallon shall have no liability or responsibility to user or any other person or entity with respect to any loss or damage caused or alleged to be caused directly or indirectly through the use of this documentation or the MINIPROP program. -7- Distribution and Use of MINIPROP -------------------------------- MINIPROP is a copyrighted program. All rights are retained by the author. MINIPROP is not to be sold; nor is it to be used for commercial purposes. You may freely distribute MINIPROP, and you are encouraged to do so, but you may not charge for doing so. The following files should be included in any distribution: MP.COM MP1.000 MP1.CHN MP2.CHN MP3.CHN MP4.CHN MP.DOC MP.ATL READ.ME MINIPROP is a user-supported program. This means that if you find MINIPROP useful you should consider sending a contribution in the suggested amount of $25.00 to the author: Sheldon C. Shallon 11058 Queensland St. Los Angeles, CA 90034-3029 Your comments and suggestions regarding MINIPROP will be welcome. Please enclose a self-addressed stamped envelope if you wish a reply. Good DXing, Shel, W6EL 2-24-87 -8- 2. Starting MINIPROP -------------------- If you have not already done so, please make a working copy of MINIPROP. The disk on which you received MINIPROP should be put away for safekeeping, and the working copy used when you want to run MINIPROP. Do not write protect the working copy because MINIPROP has to able to write to the disk. Your working disk should contain the following files: MP.COM (Required to start MINIPROP.) MP1.000 (You cannot run a MINIPROP prediction without this file.) MP1.CHN (Required to start MINIPROP.) MP2.CHN (Necessary for the DX Compass feature only.) MP3.CHN (You will not be able to change several of the built-in prediction parameters without this file.) MP4.CHN (You will not be able to use the MINIPROP utilities without this file.) MP.DOC (This MINIPROP documentation.) MP.ATL (Atlas of latitudes and longitudes. Not essential, but very helpful.) READ.ME (Help in starting MINIPROP.) In addition, a MP.DEF file will be created automatically the first time you run MINIPROP. This file will hold any changes you make to several of the values and settings used in the MINIPROP predictions, as well as the latitude and longitude of your location. Be sure there is room on the disk and in the disk directory for this short file. All of the MINIPROP files should be on the logged disk drive and in the current directory. To run MINIPROP, type "MP" following the > prompt from your computer's operating system. (In this documentation, everything you are to enter on your computer keyboard appears in quotes. You should type everything between the quotes exactly as shown, but do not type the quotes. You may always use either upper or lower case letters.) Then press the ENTER or RETURN key, depending on the keyboard of your computer. When running MINIPROP, you will see this key referred to on the screen as <ENTER>, <RETURN>, or <RTN>. After MINIPROP has been loaded from disk into RAM, an opening message and the MINIPROP master menu will appear on the screen. -9- 3. The Master Menu ------------------ The MINIPROP master menu will appear on your screen as follows: MASTER MENU 0. Exit from MINIPROP (Quit) 1. Run a MINIPROP prediction (you may also press <ENTER>) 2. DX Compass (directions of band openings) 3. Change prediction parameter defaults 4. MINIPROP utilities Your choice : If you do not wish to continue, enter "0" to terminate MINIPROP and return to the operating system. You may also enter "Q" or "X". Use choice 1 to predict propagation between two locations (terminals). This is the choice you will probably use most often. You may also press just <ENTER> or <RETURN> to invoke this choice. See Section 4 below. Choice 2 will give you a picture of the highest frequencies that are most likely to be open to DX in several directions from a specified location (terminal) at a given time of day. See Section 5 below. Choice 3 gives you the option to change certain prediction parameters from their default values. These options are: Change frequencies used in signal level predictions Change antenna minimum radiation angle used in predictions Suppress output of low signal levels Suppress output of signal levels at frequencies higher than predicted FMUF Change path (short or long) to be computed first Restore original set of MINIPROP defaults More information on these options can be found in Section 6 of this documentation. Choice 4 gives you access to the MINIPROP utilities. With these utilities you can: Create or modify Terminal A default Display entries in MINIPROP atlas Add, modify, or delete entry in MINIPROP atlas Display MINIPROP documentation on screen Send MINIPROP documentation to printer Print table of great-circle bearings Convert version 1 MINIPROP.ATL to version 2 MP.ATL See Sections 7 through 14 of this documentation for more information about the MINIPROP utilities. -10- 4. Running a MINIPROP Prediction (Master Menu Choice 1) ------------------------------------------------------- Latitudes and Longitudes ------------------------ To compute a propagation prediction between two terminals, MINIPROP needs to know the locations of those two terminals. A location is defined in terms of its latitude and longitude. You will be asked for the latitude and longitude of the terminals at the two ends of the propagation path. One of the terminals is called Terminal A; the other is Terminal B. It makes no difference which terminal is A and which is B. Latitude is a measure of angular distance north or south of the earth's equator. It is measured in degrees. The latitude of the equator is 0 degrees. The north pole is at 90 degrees north latitude, and the south pole is at 90 degrees south latitude. Latitudes can never exceed 90 degrees in magnitude. To distinguish between north and south latitudes, the latter must be preceded by a minus (-) sign. For example, 40 degrees north latitude would be entered as 40; 40 degrees south latitude would be entered as -40. Do not place a plus (+) sign in front of north latitudes. Longitude is a measure of angular distance east or west of the prime (Greenwich) meridian. It is measured in degrees. The longitude of the prime meridian is 0 degrees. Longitudes to the west of the prime meridian (e.g., in the western hemisphere) are west longitudes. Longitudes to the east of the prime meridian (e.g., in the eastern hemisphere) are east longitudes. The meridian half way around the world from the prime meridian is at longitude 180 degrees; its longitude can be given as either 180 degrees east or 180 degrees west (180 or -180). Longitudes usually have magnitudes between 0 and 180 degrees. However, any particular meridian of longitude can be reached by travelling either east or west from the prime meridian. Therefore, a longitude of 90 degrees west is equivalent to a longitude of 270 degrees east, for example. MINIPROP will accept longitudes with magnitudes between 0 and 360 degrees. To distinguish between west and east longitudes, the latter must be preceded by a minus (-) sign. For example, 100 degrees west longitude would be entered as 100; 100 degrees east longitude would be entered as -100. Do not place a plus (+) sign in front of west longitudes. An atlas containing latitudes and longitudes of more than 350 locations is supplied with MINIPROP, but you will probably have need for your own latitude and longitude and for latitudes and longitudes of other locations that are not in the MINIPROP atlas. You can generally find these in atlases that are available in bookstores and libraries, or you may scale them from maps or charts. A note of caution is in order with respect to latitudes and longitudes that are tabulated in atlases. They are usually shown as decimal numbers, but are often in a degree.minute format. Thus, 40.54 might mean 40.54 degrees, but it usually means 40 degrees, 54 minutes. If the latter is meant, the equivalent decimal value is 40.9 degrees. MINIPROP will accept latitudes and longitudes as decimals or in a degree minute second format. If you wish to enter a latitude or longitude in the latter format, leave one blank space between the degrees and minutes, and another between the minutes and seconds, if any. Leading and trailing blank spaces are invalid. Here are some examples. All of the values in each column -11- are equivalent. "40.9" "0.5" "-28 10 30" "-135" (east longitude) "40 54" "00 30" "-28 10.5" "225" (west longitude) "40 54 0" "00 30 0" "-28.175" "40 54 00" "00 30 00" The following entries are invalid. "33 60" (Minutes and seconds must be less than 60.) "118 25" (Too many blank spaces.) "-34 -25" (Put minus sign in front only.) " 42" (Leading blanks not allowed.) "42 " (Trailing blanks not allowed. "85.5 25" (Decimal allowed only in last part of entry.) "91" (If a latitude, may not exceed 90.) "361" (Longitudes may not exceed 360.) "+34" (Leading + sign not needed or allowed.) Entering Terminal A Data ------------------------ When you run a MINIPROP prediction you will see the following prompt on the screen. Enter Terminal A latitude (or <RTN> for default), or prefix, or <?> : You have four choices: (1) You may enter the latitude of Terminal A. (2) you may press <RTN> to use the Terminal A default location. (Remember, <RTN> means you should press the RETURN or ENTER key.) (3) you may enter the country prefix (or other unique identifier) if you want to use a MINIPROP atlas entry. (4) you may press <?> followed by <RTN> if you want to be reminded of the prefixes that are available in the atlas. If you enter a latitude in response to the latitude prompt, you will next be prompted for the longitude of Terminal A. Enter the longitude. Then you will be asked for the name of Terminal A. You may want to enter a call sign, city name, or other identifier. The name you enter will appear in the prediction heading as an identifier for your use. MINIPROP makes no other use of the name. The name may contain up to 17 characters and blanks. You may press only <RTN> if you do not want to enter a name. If you press only <RTN>, MINIPROP will look in the MP.DEF disk file for the default latitude, longitude, and name of Terminal A. This saves you the trouble of entering your own latitude, longitude, and terminal name each time you want a prediction on a path from your own station. If you have not already created a Terminal A default for your own location, one of the MINIPROP utilities (Master Menu choice 4) will help you do so. If you enter a prefix in response to the latitude prompt, MINIPROP will search the MP.ATL atlas file to find the entry with that prefix. The contents of the atlas entry will appear on the screen and the displayed values will be used in the prediction. If you need to be reminded of the prefixes in the MINIPROP atlas, press -12- <?>. All of the prefixes in the atlas will appear on the screen, followed again by the above prompt. Entering Terminal B Data ------------------------ The following prompt will appear next. Enter Terminal B latitude, or prefix, or <?> : Except for the Terminal A default, your choices are the same as for Terminal A. Proceed as for Terminal A. You may not use the Terminal A default location for Terminal B. Entering the Date ----------------- Next you will be asked for the date to be used in the prediction. MINIPROP needs the date to compute the position of the sun, the times of sunrise and sunset, and the directions of the gray lines at the path terminii. Enter the date as a six-digit number with no leading, trailing, or embedded spaces and no punctuation. Examples: 122585 is December 25, 1985 010187 is January 1, 1987 070410 is July 4, 2010 MINIPROP will convert the last two digits to a year between 1945 and 2044, inclusive. This 100-year span allows you to obtain current predictions, to compare MINIPROP predictions with actual propagation records back to the beginning of the post-WW II DXCC, and to predict propagation well into the future. Invalid dates (e.g., 022987) will not be accepted. Entering the Sunspot Number or Solar Flux ----------------------------------------- You have to enter one more item of information. You will see the following prompt on the screen. Sunspot number (or solar flux, e.g., F70) for above date? If you want to enter a sunspot number, just enter the number and press <RTN>. If you want to enter a solar flux value, first enter "F" or "f", immediately followed (no blanks) by the value and press <RTN>. For example, a sunspot number of 45 would be entered as "45"; a solar flux of 70 would be entered as "F70" or "f70". MINIPROP will do the conversion for you. The sunspot number and solar flux are both measures of solar activity. They are highly, but not 100-percent, correlated with each other. Therefore, a range of sunspot numbers can correspond to a particular value of solar flux, and vice versa. For example, the sunspot number was 0 on eight days in November, 1986; on those days, the solar flux value ranged from 71 to 80. On six days when the value of the solar flux was 76, the sunspot number ranged from 0 to 23. Various formulas to approximate the relationship between sunspot number and solar flux have appeared in the literature. MINIPROP uses the -13- following formula published by the Institute for Telecommunication Sciences (6): solar flux = 63.75 + 0.728 ssn + 0.00089 ssn^2 In this formula, ssn is the 12-month moving average Zurich sunspot number, and ssn^2 is the square of that number. The solar flux is in units of 10^-22 watts per square meter per Hz. MINIPROP will accept sunspot numbers between 0 and 390, and solar flux values between 60 and 483. However, if you input a solar flux value between 60 and 63.75, MINIPROP will substitute a solar flux value of 63.75 corresponding to a sunspot number of 0. Solar flux values less than 60 will not be accepted. Predicted sunspot numbers are published monthly in conjunction with the propagation charts in QST, and in George Jacobs' propagation column in CQ. QST also predicts the solar flux value, but the formula relating QST's predicted sunspot number and solar flux value differs somewhat from the above formula used in MINIPROP. Daily values of solar flux are broadcast by WWV at 18 minutes past each hour. In addition, the weekly KH6BZF Reports contains up-to- date sunspot numbers, solar flux values, A and K indices, propagation conditions, and other useful information. MUFs do not seem to follow day-to-day variations in solar activity, so I prefer to use monthly predicted sunspot numbers. However, a change in solar activity, when sustained for a period of time (several days, say), does influence MUFs. Therefore, you may want to use solar flux values representing the average of the values broadcast by WWV for the past several days. Absorption in the D region reacts more quickly to solar activity, but significant changes in predicted signal strengths would not be expected except for very large changes in solar activity, and then only on daytime paths at the lower frequencies. MINIPROP will start computing the propagation prediction as soon as you have entered a sunspot number or solar flux value. An Example ---------- As an example, let's predict what propagation will be like on the path from Omaha, Nebraska, to Agalega (3B6) on January 25, 1990, if the predicted smoothed sunspot number is 114. I have chosen this example because it demonstrates the several elements of a MINIPROP prediction and illustrates how band openings are predicted on the 10- through 80-meter bands. Start MINIPROP by entering "MP" following the > prompt from your computer's operating system. When the MINIPROP master menu appears on the screen, enter the number "1" or press the ENTER or RETURN key. We will assume that the latitude and longitude of Omaha have not been entered as the Terminal A default and are not in the MINIPROP atlas, so we have to look them up and enter them manually. My Rand McNally atlas lists the coordinates as 41 deg 15 min N, 95 deg 56 min W. In response to the prompt for the latitude of Terminal A, enter "41 15". In response to the longitude prompt, enter "95 56". In response to the name prompt, we can enter any string -14- of up to 17 characters. Let's use only the city name; enter "Omaha". Let's use the MINIPROP atlas entry for Agalega. In response to the prompt for the latitude of Terminal B, enter "3B6". For the date enter "012590". For the sunspot number enter "114". After a brief delay, the following display will appear on the screen while MINIPROP continues to compute the prediction. MINIPROP 01-25-1990 Sunspot Number : 114.0 Flux : 158.3 Min. Radiation Angle : 1.5 deg TERMINAL A : Omaha TERMINAL B : Agalega Latitude : 41.25 N Latitude : 10.42 S Longitude : 95.93 W Longitude : 56.65 E Sunrise : 1346 UTC Sunrise : 0211 UTC Gray line : 26/206 deg Gray line : 19/199 deg Sunset : 2326 UTC Sunset : 1440 UTC Gray line : 334/154 deg Gray line : 341/161 deg SHORT-PATH Bearing from A to B : 45.8 deg Bearing from B to A : 326.7 deg Path Length : 15651 km 9726 mi (U.S.) LONG-PATH Bearing from A to B : 225.8 deg Bearing from B to A : 146.7 deg Path Length : 24349 km 15131 mi (U.S.) The second line shows the date you specified in expanded form showing the four-digit year. On the next line are the sunspot number you entered and the equivalent solar flux value. If you had entered the solar flux value, MINIPROP would have computed and displayed the equivalent sunspot number. The third line also shows the antenna minimum radiation (take-off) angle that is being used in computing the prediction. The default (initial setting) for this parameter is 1.5 degrees. If your antenna installation or horizon obstructions preclude achievement of this low an angle, Master Menu choice 3 allows you to increase the value. (See Section 6 below.) The value may also be decreased if appropriate to your installation. For this example, we will use the default 1.5 degrees. The next seven lines contain two columns of information, one for each of the terminals. For each terminal, the name, latitude, and longitude are displayed. In this example the latitudes and longitudes were specified in degree-minute format, but MINIPROP has converted them to decimals. Although shown to two decimal places, latitudes and longitudes are carried to greater accuracy within MINIPROP. Instead of a plus (implied) or minus sign, a letter (N, S, E, or W) indicating the direction from the equator or the prime meridian is shown. -15- Sunrise and sunset times and directions of the gray lines are also shown for each terminal. There are several definitions of sunrise and sunset (e.g., civil, nautical, astronomical), and times can differ by several minutes between the different definitions. MINIPROP defines sunrise and sunset as the times when the center of the sun is on the celestial horizon. The gray line is the fuzzy band around the earth separating daylight and darkness. Many DXers point their antennas along the gray line at sunrise and sunset to look for DX. For each sunrise and sunset, the first gray line direction shown is the most northerly direction and the second direction is the most southerly; the two directions are 180 degrees apart. In this example, sunrise at Omaha is at 1346 UTC. Around that time you would point your antenna at 26 or 206 degrees east of north to point along the gray line. Next, the bearings and path lengths are shown for both the short great- circle path and the long great-circle path between the two terminii. You will note that on neither path do the bearings from one terminal to the other differ by 180 degrees (e.g., 45.8 and 326.7 degrees on the short path). This point is mentioned because some people are surprised that this is true. Except for some unique geometries, the bearings will not be 180 degrees apart. Of course, the short-path and long-path bearings from any one terminal are 180 degrees apart (e.g., 45.8 and 225.8 degrees). By the time you have read this far, MINIPROP will probably have finished computing the propagation prediction for the short path. MINIPROP displays its progress at the bottom of the screen while it is computing the prediction. It displays a period (.) periodically while it is computing absorption along the path, a lower case f while computing F-layer MUF, and a lower case e while computing the E-layer cutoff frequency. When MINIPROP has finished computing the prediction, "Press any key when ready for predictions." appears at the bottom of the screen. Press any key when you are ready. The table of predictions on the next page will appear on your screen. The information displayed at the top of the screen is similar to the information in the previous display, but somewhat abbreviated. Bearings and path length are shown only for one path, in this case the short path. MINIPROP has computed and displayed the minimum number of F hops corresponding to the minimum radiation angle (1.5 degrees) that appeared on the previous display. In this example, 5 F hops are required. The resulting predicted radiation angle is shown to be 5 degrees. The predicted F-layer MUF (FMUF), E-layer cutoff frequency (ECOF), and received signal levels are shown for every two hours UTC. The predicted signal levels are shown for frequencies in the five primary hf bands. You may change these built-in frequencies to any five frequencies of your choice between 3 and 30 MHz. (See Section 6 below.) The signal levels are in dB with respect to 0.5 microvolt "behind" 50 ohms, and assume a matched antenna load. On my receiver 0.5 microvolt produces an S3 signal. So 0 dB would be S3. At 5 dB per S unit, 10 dB would be S5, 30 dB would be S9, etc. The signal levels assume 100 watts radiated power with half-wave dipole antennas in free space at both ends of the path, and with the antennas oriented for maximum gain along the path. Add or subtract whatever number of dB you think appropriate for the antennas and power levels in use. -16- Predicted signal levels are computed independently of the FMUF and ECOF under the assumption that the number of F hops (in this case 5) shown in the header are present at all times and for all frequencies, and that there is no E-layer cutoff. (To take E-layer reflections into account in computing signal levels would be time prohibitive.) This is important to remember: SIGNAL LEVEL PREDICTIONS ASSUME THAT A REFLECTING F LAYER IS ALWAYS PRESENT AND THAT THERE IS NO REFLECTING E LAYER. MINIPROP (TM) SHORT-PATH PREDICTIONS 01-25-1990 Path Length : 15651 km Sunspot Number : 114.0 Flux : 158.3 F Hops : 5 Radiation Angle : 5 deg TERMINAL A : 41.25 N 95.93 W Omaha Bearing to B : 45.8 deg TERMINAL B : 10.42 S 56.65 E Agalega Bearing to A : 326.7 deg Terminal A Sunrise/Set : 1346/2326 UTC Terminal B Sunrise/Set : 0211/1440 UTC ----------- SIGNAL LEVELS ABOVE 0.5 uV ------------ UTC FMUF ECOF 3.6 MHZ 7.1 MHZ 14.1 MHZ 21.2 MHZ 28.3 MHZ 0000 15.9 5.8 40.5 a 35.5 A 29.2 A 24.9 0200 12.5 4.6 39.3 a 35.1 A 29.1 B 0400 14.0 13.8 8.4 a 22.4 a 25.1 B 0600 14.8 17.8 -0.9 a 17.7 a 19.5 0800 14.2 19.3 10.7 a 16.2 1000 11.3 19.1 6.6 1200 11.5 16.9 6.9 1400 17.3 11.6 10.8 A 16.3 1600 26.1 14.1 2.7 a 18.9 A 20.1 A 18.9 B 1800 30.8 15.3 -12.8 a 13.7 a 22.3 a 21.7 A 19.9 A 2000 29.5 14.4 6.9 a 21.8 a 24.9 a 22.9 A 20.6 A 2200 23.3 10.8 28.0 a 30.4 a 27.6 A 24.2 A 21.3 <G>raph, <T>able, <P>rint table, <Q>uit, <M>enu, or <L>ong path ? The "A", "a", "B", and "b" flags are included in the predictions to flag predicted band openings and to aid in interpreting the predicted signal levels. The table on the next page shows how the flags indicate the relationship that exists between the frequency at the top of a column and the FMUF and ECOF, and also shows the probability that propagation on the path can be supported by the F layer. "A"s or "a"s in a particular frequency column flag the times that openings are most probable on that frequency. At these times, the frequency at the top of the column is less than the predicted FMUF. Therefore, it is expected that the probability of F-layer propagation is greater than 50 percent. The difference between "A" and "a" is that the frequency is above the ECOF in the first case, but below the ECOF in the second. (The "A" flag has the same meaning as the "+" flag in MINIPROP version 1.0.) When the "A" flag is present, the predicted signal levels apply. When the "a" flag is present, usually when one or both of the two terminii is in daylight, E hops are added to, or substituted for, F hops. This causes additional absorption loss, and possibly additional ground reflection loss, that results in weaker signals than the predicted values. The reduction of received signal level can be very large, particularly at the lower frequencies. Transmitter power and high antenna gains may sometimes be used to overcome the increased signal loss. -17- This allows you to hear foreign broadcast stations in the middle of the day on the 41 meter band, but this approach usually is not practical for radio amateurs. Frequency at Top ! Flag ! Probability of of Column ! ! F-Layer Support ======================================================== Below FMUF ! ! ---------------------!----------! and above ECOF ! A ! More than 50% ---------------------!----------! and below ECOF ! a ! ======================================================== Between FMUF and HPF ! ! ---------------------!----------! and above ECOF ! B ! 10 - 50% ---------------------!----------! and below ECOF ! b ! ======================================================== Above HPF ! None ! Less than 10% ======================================================== "B"s or "b"s in a particular frequency column flag the times that the frequency at the head of the column is greater than the predicted FMUF, but is predicted to be less than the F-layer HPF. Therefore, the probability of F- layer propagation is expected to be less than 50 percent, but greater than 10 percent. When this possible opening actually occurs, and if the flag is "b", signal levels are expected to be weaker than shown because E-layer cutoff is to be expected; the predicted signal levels apply when the opening occurs and the flag is "B". Propagation may occur, with low probability, on frequencies even higher than the HPF, so predicted signal levels are shown for frequencies up to 150 percent of the predicted FMUF. The display of signal levels is normally suppressed for frequencies greater than 150 percent of the FMUF, but this suppression can be cancelled if you wish; see Section 6 below. Of course, the signal levels that are shown at the higher frequencies are only applicable when the actual MUF is high enough to permit propagation at these frequencies. The display of signal levels below -20 dB is normally suppressed because weaker signals are generally unusable by radio amateurs, even after allowance is made for transmitter power and antenna gains. The blanks in the 3.6- and 7.1-MHz columns are a result of this suppression. The suppression threshold can be changed; see Section 6 below. In this example, 10 meters will most probably be open with good signals from 1800 to 2000 UTC, as indicated by the "A" flag in the 28.3-MHz column. The "B" flag in this column indicates that there is a probability between 10 and 50 percent that the band will open as early as 1600. If the band does not open early, the signal level shown at 1600 has no meaning. 15 meters will be open from 1600 to 2200 with a probability in excess of 50 percent. -18- 20 meters will probably open around 1400 UTC with only fair signals. Signals will build until 1600, drop some around 1800 to 2000 as a result of E- layer cutoff, and then build to strong signals around 0000 UTC. The band will probably go out on this path from 0200 to 0400; predicted signal levels opposite the "B" flags apply only if the band stays open, and should be disregarded otherwise. 20 meters will be open again from 0600 to 0800, but signals will be weaker than shown because of E-layer cutoff. On 40 meters, signals will be good from 0000 to 0200. E-layer cutoff will reduce signal levels, probably below usable levels because of the low frequency, during most of the remainder of the day. E-layer cutoff will reduce all signal levels shown for 80 meters, but signals will be best around 0000 to 0200 UTC. The Command Line ---------------- At the bottom of the screen is a line containing several command choices. Make your choice by pressing the initial letter of the command; either upper or lower case may be used. <G>raph. This choice causes the following screen display to appear. SHORT-PATH PREDICTIONS 01-25-1990 Omaha TO Agalega Sunspot Number : 114.0 Flux : 158.3 F Hops : 5 Radiation Angle : 5 deg MHZ X = FMUF O = ECOF MHZ 30 -----------------------------------XX+XXX-------- 30 28 XX X 28 26 X XX 26 24 X X 24 22 X X 22 20 ---------------OOOOOO--------X----------------X-- 20 18 OOOO OOO X X 18 16 X OO OO X OOOO X 16 14 X XXXXXXXXXXXX OO OOOO OOOO 14 12 XXXX O XXXXXXXX OOO O 12 10 ------O-------------------------------------OO--- 10 8 O O 8 6 O OO 6 4 OOOO 4 2 2 0 ------------------------------------------------- 0 0 0 0 0 0 1 1 1 1 1 2 2 0 U 0 2 4 6 8 0 2 4 6 8 0 2 0 T <G>raph, <T>able, <P>rint table, <Q>uit, <M>enu, or <L>ong path ? The graph uses the letters X and O to plot FMUF and ECOF versus time. The time resolution is 30 minutes instead of the 2-hour resolution in the previous prediction table. However, the limited screen height limits the frequency resolution to 2 MHz. When both an X and an O should appear in the same location on the graph, the one that is predicted to be at the highest frequency -19- appears. At 0400 UTC in this example, FMUF and ECOF are both 14 MHz to the nearest 2 MHz; an X appears because the FMUF of 14.0 MHz exceeds the ECOF of 13.8 MHz. At 1300, only an O appears at 14 MHz because the ECOF is higher than the FMUF, with both rounding to 14 MHz. (The predicted ECOF of 14.9 MHz exceeds the predicted FMUF of 13.5 MHz.) The plus (+) sign at 1830 indicates that the predicted FMUF exceeds 31 MHz. The command line is repeated below the graph. <T>able. This choice causes the prediction table to reappear. <P>rint table. This choice sends the prediction table to your printer. The longer page length as compared to the screen height allows predictions to be printed for every 30 minutes instead of every 2 hours. Otherwise, the table is the same as seen on the screen. 57 lines will be printed, so make sure the paper is adjusted in your printer so that printing can start within 10 lines from the top of the page. It is assumed that your page length is 66 lines. <Q>uit. This choice terminates MINIPROP. <M>enu. This choice causes the MINIPROP master menu to reappear on the screen. From the master menu you can choose to run another prediction, or you can select one of the other master menu choices. <L>ong path. This choice is available only after the short-path prediction has been displayed first, and causes MINIPROP to compute a propagation prediction for the long great-circle path between terminals A and B. Both table and graph displays are available as in the above example. Long- path propagation is difficult to predict reliably; predicted openings often do not occur, particularly on the higher frequencies. <S>hort path. This choice is available only after the long-path prediction has been displayed first, and causes MINIPROP to compute a propagation prediction for the short great-circle path between terminals A and B. -20- 5. DX Compass (Master Menu Choice 2) ------------------------------------ The DX Compass is a screen display showing the highest FMUF you can expect on twelve bearings separated at intervals of 30 degrees from a specified location for Terminal A and at any specified time of day. This feature is especially useful for planning your operations during DX contests. Entering Data ------------- Data entry is similar to the data entry described above in Section 4 for MINIPROP predictions. Only one terminal is used in the DX Compass, so you will not be asked for Terminal B data. Entry of Terminal A data, the date, and the sunspot number or solar flux are the same as in Section 4. One new piece of data must be entered. The following prompt will appear on the screen after the sunspot number or solar flux is entered. DX Compass for what UTC (e.g., 0215) (or <RTN> to quit)? As indicated in the prompt, a four-digit UTC in 24-hour format should be entered. Valid times are from 0000 to 2400. Press <RTN> if you want to quit the DX Compass and return to the MINIPROP master menu. An Example ---------- As an example, let's use the same data we used in the prediction example in Section 4, except that there is no Terminal B. Terminal A is Omaha, Nebraska. The date is January 25, 1990. We assume a predicted smoothed sunspot number of 114. Start MINIPROP by entering "MP" following the > prompt from your computer's operating system. When the MINIPROP master menu appears on the screen, enter the number "2". In response to the prompt for the latitude of Terminal A, enter "41 15". In response to the longitude prompt, enter "95 56". For the name of Terminal A, enter "Omaha". For the date enter "012590". For the sunspot number enter "114". For UTC, let's use the time of sunrise. From the example in Section 4, we know this to be 1346; so enter "1346". When MINIPROP has finished computing the DX Compass, the display at the top of the next page will appear on the screen. The time you specified is shown in the center of the display together with the specified latitude, longitude, and date. The FMUF values are arranged in a "circle" around the center of the display. Immediately below "FMUF" in the top line is the FMUF that applies on a bearing of 0 degrees (due north) from Dallas. The other FMUFs around the DX Compass are for bearings in steps of 30 degrees. -21- Sunrise: 1346 UTC FMUF Radiation Angle: 1.5 deg Sunset: 2326 UTC Sunspot Number: 114.0 Omaha 13.2 Solar Flux: 158.3 12.1 15.9 11.9 19.8 1346 UTC 13.3 41.25 N 95.93 W 25.3 01-25-1990 15.6 26.9 18.6 24.9 22.2 DX Compass for what UTC (e.g., 0215) (or <RTN> to quit)? The displayed values of FMUF are an indication of the highest-frequency bands that can be expected to be open to DX on either a short or long great- circle path in the different directions around the compass from Terminal A. In this example, 10 meters is not yet open in any direction at the time of sunrise. 15 meters would be expected to be open, with a probability exceeding 50 percent, to DX on bearings between 90 and 180 degrees from Omaha. 20 meters would be expected to be open on bearings of 30 degrees, through south, to 240 degrees. 20 meters would not yet be open from 300 through 360 degrees, but 40 meters (and 30 meters) would be expected to be open in these directions. Keep in mind that the predicted values of only the FMUF are shown, so you cannot tell, from the DX Compass alone, how strong the received signals might be. However, the first band lower in frequency than the indicated FMUF will probably be usable for working DX. A different interpretation of the compass display applies when Terminal A is at either the north or south pole. Instead of compass bearings, the twelve positions around the "circle" represent meridian longitudes measured west from the prime meridian. For example, the FMUF shown in the 30-degrees position would be the maximum FMUF to be expected on a path from the pole along the 30- degree west meridian. The time prompt appears again at the bottom of the screen. You can enter additional times to see how the expected band openings shift during the day. Press only <ENTER> or <RETURN> when you want to quit and return to the MINIPROP master menu. -22- 6. Changing Prediction Parameters (Master Menu Choice 3) -------------------------------------------------------- There are several default (preset) values and settings (e.g., frequencies) used in the MINIPROP predictions. Five of these can be changed by the user. In addition, you can restore the original set of MINIPROP default values and settings. If you make any changes, you will be given the chance to save them in the MP.DEF file of default settings upon returning to the master menu. Your settings will then be in effect each time you use MINIPROP. If you do not save your changes, they will remain in effect only during the current MINIPROP session. To change any of the defaults, first start MINIPROP by entering "MP" following the > prompt from your computer's operating system. When the MINIPROP master menu appears on the screen, enter the number "3". The following Defaults Change Menu will appear on the screen. DEFAULTS CHANGE MENU 0. Return to MASTER MENU 1. Change frequencies used in signal level predictions 2. Change antenna minimum radiation angle used in predictions 3. Suppress output of low signal levels 4. Suppress output of signal levels at frequencies higher than predicted FMUF 5. Change path (short or long) to be computed first 6. Restore original set of MINIPROP defaults Your choice : To make your choice, enter a number, 0 to 6. Choice 0 will return you to the MINIPROP Master Menu. Choices 1 through 6 are explained in the following sections. Change Frequencies Used in Signal Level Predictions --------------------------------------------------- In the MINIPROP propagation predictions described above in Section 4, signal levels are predicted for frequencies of 3.6, 7.1, 14.1, 21.2, and 28.3 MHz. You may change these frequencies to any combination of five frequencies between 3 and 30 MHz. This will allow you to obtain signal level predictions for frequencies in the 12-, 17-, or 30-meter bands or in the shortwave broadcast bands, for example. The frequencies currently in effect will be displayed. You will then be asked if you want to change the frequencies. If you answer "N" (without the quotes), the Defaults Change Menu will reappear. If you enter "Y", the following (top of next page) will appear. -23- You may enter 0 to 5 frequencies between 3 and 30 MHz. If you do not enter at least one frequency, signal levels will not be included in the predictions. Enter your frequencies, if any, one at a time. Press only <ENTER> or <RETURN> when finished. Frequency 1 : Press only <ENTER> or <RETURN> if you do not want signal levels to appear in the predictions; this will save time when running predictions if you are only interested in the FMUF and ECOF predictions. If you do want signal levels to appear, enter one to five frequencies, one at a time. You may enter them in any order; MINIPROP will place them in numerical order and will round them to the nearest 0.1 MHz. Duplicate frequencies will be rejected. If you want to enter less than five frequencies, press only <ENTER> or <RETURN> when asked for the next frequency. MINIPROP will display the new frequencies that are now in effect and will ask you if you want to change them. If you are not satisfied with the frequencies, enter "Y" and you will again be asked to enter your frequencies. When you are satisfied with the displayed frequencies, enter "N" and the Defaults Change Menu will reappear. You may select other default parameters that you want to change, or you may choose to return to the MINIPROP Master Menu. If you make the latter choice, and you have changed any of the defaults, you will be given the opportunity to save your changes in the MP.DEF defaults file before the MINIPROP Master Menu is reloaded. Change Antenna Minimum Radiation Angle Used in Predictions ---------------------------------------------------------- The minimum usable antenna radiation (take-off) angle depends primarily upon antenna heights and horizon obstructions. In both the propagation predictions and the DX Compass, MINIPROP assumes this minimum angle to be 1.5 degrees unless you change it. You may change the antenna minimum radiation angle to any value between 0 and 45 degrees. MINIPROP uses this value to determine the minimum number of F hops required on a given path, and then computes the actual antenna radiation angle from the resulting path geometry. If you specify too great a radiation angle, the number of hops on a given path may be excessive. In this case, a screen message will advise you that the prediction computation has been aborted. The antenna minimum radiation angle currently in effect will be displayed. You will then be asked if you want to change the angle. If you answer "N", the Defaults Change Menu will reappear. If you enter "Y", you will be asked to enter an angle between 0 and 45 degrees. MINIPROP will display the new antenna minimum radiation angle that is now in effect and will ask you if you want to change it. If you are not satisfied with the value, enter "Y" and you will again be asked to enter an angle. When you are satisfied with the displayed angle, enter "N" and the Defaults Change Menu will reappear. You may select other default parameters that you want to change, or you may choose to return to the MINIPROP Master Menu. If you make the latter choice, and you have changed any of the defaults, you will be given the opportunity to save your changes in the MP.DEF defaults file before the -24- MINIPROP Master Menu is reloaded. Suppress Output of Low Signal Levels ------------------------------------ In the discussion of the prediction example in Section 4, it was stated that signal levels below -20 dB with respect to 0.5 microvolt are normally not displayed or sent to the printer because weaker signals are generally unusable by radio amateurs. However, listeners to shortwave broadcasting stations that use high power and high-gain antennas might find it desirable to use a lower threshold which, after correction for the power and antenna gain, might result in a usable received signal strength. You may set the suppression threshold to 0, -20, -40, or -60 dB according to your needs, or you may completely eliminate suppression of the output of low signal levels. The suppression level currently in effect will be displayed. You will then be asked if you want to change the suppression threshold. If you answer "N", the Defaults Change Menu will reappear. If you enter "Y", the following will appear. A Do not show signal levels that are below 0 dB with respect to 0.5 microvolt. B Do not show signal levels that are below -20 dB with respect to 0.5 microvolt. (Default) C Do not show signal levels that are below -40 dB with respect to 0.5 microvolt. D Do not show signal levels that are below -60 dB with respect to 0.5 microvolt. E Do not suppress output of low signal levels. Your choice : To make your choice, enter a letter, A through E. MINIPROP will display the new suppression threshold that is now in effect and will ask you if you want to change it. If you are not satisfied with the threshold, enter "Y" and you will again be asked to enter your choice of A through E. When you are satisfied with the new threshold, enter "N" and the Defaults Change Menu will reappear. You may select other default parameters that you want to change, or you may choose to return to the MINIPROP Master Menu. If you make the latter choice, and you have changed any of the defaults, you will be given the opportunity to save your changes in the MP.DEF defaults file before the MINIPROP Master Menu is reloaded. Suppress Output of Signal Levels at Frequencies Higher than Predicted FMUF -------------------------------------------------------------------------- Signal level predictions are normally suppressed for frequencies greater than 150 percent of the predicted FMUF, but you may cancel this suppression. This is a toggle; the suppression is either on or off. -25- The current setting of the toggle will be displayed. You will then be asked if you want to change the setting to the other state. If you answer "N", the Defaults Change Menu will reappear. If you enter "Y", the setting will be reversed. MINIPROP will display the new toggle setting that is now in effect and will ask you if you want to change it. If you are not satisfied with the setting, enter "Y" and the setting will again be reversed. When you are satisfied with the toggle setting, enter "N" and the Defaults Change Menu will reappear. You may select other default parameters that you want to change, or you may choose to return to the MINIPROP Master Menu. If you make the latter choice, and you have changed any of the defaults, you will be given the opportunity to save your changes in the MP.DEF defaults file before the MINIPROP Master Menu is reloaded. Change Path (Short or Long) to be Computed First ------------------------------------------------ Short-path predictions are normally computed first, long-path second. You may reverse this order. This is a time saver if you need only the long-path prediction. This a toggle. The current setting of the toggle will be displayed. You will then be asked if you want to reverse the setting. If you answer "N", the Defaults Change Menu will reappear. If you enter "Y", the setting will be reversed. MINIPROP will display the new toggle setting that is now in effect and will ask you if you want to change it. If you are not satisfied with the setting, enter "Y" and the setting will again be reversed. When you are satisfied with the toggle setting, enter "N" and the Defaults Change Menu will reappear. You may select other default parameters that you want to change, or you may choose to return to the MINIPROP Master Menu. If you make the latter choice, and you have changed any of the defaults, you will be given the opportunity to save your changes in the MP.DEF defaults file before the MINIPROP Master Menu is reloaded. Restore Original Set of MINIPROP Defaults ----------------------------------------- The original set of defaults built into MINIPROP are: Prediction frequencies of 3.6, 7.1, 14.1, 21.2, and 28.3 MHz Antenna minimum elevation angle of 1.5 degrees Suppression threshold for low signal levels at -20 dB Output of signal levels suppressed for frequencies higher than 150% of FMUF Short-path predictions computed before long-path predictions You will be asked if you want to restore this set of defaults. If you answer "N", the Defaults Change Menu will reappear. You may select other default parameters that you want to change, or you may choose to return to the -26- MINIPROP Master Menu. If you enter "Y", the original settings will be restored for the current MINIPROP session, and you will be asked to press any key before returning to the Defaults Change Menu. You may then select other default parameters that you want to change, or you may choose to return to the MINIPROP Master Menu at which time you will be given the opportunity to save your changes in the MP.DEF defaults file before the MINIPROP Master Menu is reloaded. -27- 7. MINIPROP Utilities (Master Menu Choice 4) -------------------------------------------- When you select Master Menu choice 4, the following MINIPROP Utilities menu will appear. MINIPROP (TM) UTILITIES 0. Exit from MINIPROP (Quit) 1. Return to MASTER MENU 2. Create or modify Terminal A default 3. Display entries in MINIPROP atlas 4. Add, modify, or delete entry in MINIPROP atlas 5. Display MINIPROP documentation on screen 6. Send MINIPROP documentation to printer 7. Print table of great-circle bearings 8. Convert version 1 MINIPROP.ATL to version 2 MP.ATL Your choice : Use choice 0 to quit MINIPROP without first returning to the Master Menu. To return to the MINIPROP Master Menu, use choice 1. Choices 2 through 8 are discussed in the following sections. 8. Create or Modify Terminal A Default (MINIPROP Utilities Choice 2) -------------------------------------------------------------------- There is probably a location you will use most often as one of the terminals when running a MINIPROP prediction. This utility allows you to save the latitude, longitude, and name of this location as the Terminal A default. Then when you want to use this location in a MINIPROP prediction or in the DX Compass, it will only be necessary to press <ENTER> or <RETURN> when you are prompted for the latitude of Terminal A; you will not have to enter the latitude, longitude, and name each time. The Terminal A Default is saved on your disk in the MP.DEF file (the same file that holds the default values of several of the prediction parameters). When you select choice 2 on the MINIPROP Utilities menu, the latitude, longitude, and name of any existing Terminal A default location will be displayed. Then you will be directed to enter your desired Terminal A default. Enter the latitude, longitude and name the same as you would enter them manually when running a MINIPROP prediction (Section 4 above). When you have finished making these entries, they will be repeated back on the screen, and you will be asked if they are correct. If you want to make any corrections, answer "N". In this case, you will again be asked to enter the latitude, longitude, and name. When the displayed entries are correct, answer "Y". You will then be asked to confirm that you want the entries saved in the MP.DEF defaults file. If you do want them saved, answer "Y"; but if you want to abort the creation or change of the Terminal A default location, answer "N". You will be directed to press any key to continue, and the MINIPROP Utilities menu will reappear. -28- 9. Display Entries in MINIPROP Atlas (MINIPROP Utilities Choice 3) ------------------------------------------------------------------ This choice allows you to view all of the entries in the MINIPROP atlas. The entries will appear in alphabetical order of the prefix. (ASCII alphabetization is used. Numerals precede letters. The numeral 0 precedes the numeral 1.) The prefix, latitude, longitude, and name will be displayed for each entry. The scrolling of the display will stop after every 20 entries; to continue, press any key. The total number of atlas entries will be displayed after the last atlas entry. If you want to terminate the atlas display before the last entry is reached, press Control-X (Hold down the CONTROL key; then type "X".). 10. Add, Modify or Delete Entry in MINIPROP Atlas (MINIPROP Utilities Choice 4) ------------------------------------------------------------------------------- You may add, modify, or delete entries in the MINIPROP atlas. The only limit on the number of atlas entries is the capacity of your disk. When you select this utility from the MINIPROP Utilities menu, the following message and list of edit choices will appear on your screen. You will be given a chance to abort before any change is made in the atlas. <A>dd an entry <M>odify an entry <D>elete an entry <R>eturn to utilities menu Your choice : Enter "A", "M", or "D" to add, modify, or delete an atlas entry. The list of available edit choices will reappear after each addition, modification, or deletion. Enter "R" to return to the MINIPROP Utilities menu. Adding an Atlas Entry --------------------- You will first be asked for the prefix to be added to the atlas. Prefixes may contain from one to six characters. Leading, trailing, and embedded spaces are not allowed, and you will not be allowed to enter an all-numeric prefix. Country prefixes, call area prefixes, station call signs, or any other unique identifier may be used. Letters may be entered in either upper or lower case; MINIPROP will convert all letters of a prefix to upper case before the entry is made in the atlas. MINIPROP will check to make sure the new prefix is not already in the atlas; if it is not, you will be asked to enter the latitude, longitude, and name for the new entry. Enter these in the same manner as they are manually entered when you run a MINIPROP prediction (Section 4 above). The latitude and longitude may be entered as a decimal or in deg min sec format. North latitudes and west longitudes are positive (with no plus sign); south and east are negative (with a minus sign). Latitudes greater than 90 degrees in magnitude, and longitudes greater than 360 degrees in magnitude, will not be accepted. Names may not exceed 17 characters in length, and may contain any -29- combination of characters. You might want to look at some examples in the atlas; use choice 4 in the MINIPROP Utilities menu. After you have entered the name, your new atlas entry will be repeated back on the screen, and you will be asked if it is correct. If you want to make any corrections, answer "N". In this case, you will again be asked to enter the prefix, latitude, longitude, and name. When the displayed entry is correct, answer "Y". You will then be asked to confirm that you want the entry put in the MINIPROP atlas file. If you do want the entry put in the atlas file, answer "Y"; but if you want to abort the addition to the atlas, answer "N". You will then be given the choice of adding, modifying, or deleting another atlas entry or returning to the MINIPROP Utilities menu. Modifying an Atlas Entry ------------------------ You will be asked for the prefix of the atlas entry that you want to modify. MINIPROP will then display the current contents of that entry, and you will be asked to enter your changes. If you do not want to change an item (prefix, latitude, longitude, or name) within an entry, just press <ENTER> or <RETURN> and the current contents for that item will appear on the screen. When you do want to change an item, enter your desired contents for that item. After the name is entered, the modified atlas entry will be repeated back on the screen, and you will be asked if it is correct. If you answer "N", the modification will be aborted. If the displayed entry is correct, answer "Y". You will then be asked to confirm that you want the modified entry put in the MINIPROP atlas file. If you do want the modified entry put in the atlas file, answer "Y"; but if you want to abort the modification, answer "N". You will then be given the choice of adding, modifying, or deleting another atlas entry or returning to the MINIPROP Utilities menu. Deleting an Atlas Entry ----------------------- You will be asked for the prefix of the atlas entry that you want to delete. MINIPROP will then display the contents of that entry, and you will be asked to confirm that you want the entry deleted. If you do want the entry deleted from the atlas file, answer "Y"; but if you want to abort the deletion, answer "N". You will then be given the choice of adding, modifying, or deleting another atlas entry or returning to the MINIPROP Utilities menu. 11. Display MINIPROP Documentation on Screen (MINIPROP Utilities Choice 5) -------------------------------------------------------------------------- Use this choice in the MINIPROP Utilities menu if you want to read this documentation on the screen. The page number at the bottom of each page will not appear on the screen, and where the documentation contains multiple adjacent blank lines, only one blank line will appear on the screen. The last line of documentation on each screen will be repeated at the top of the next screen. The scrolling of the display will stop after every 22 lines; to continue, press any key. This documentation is lengthy, so it will take a while to read it all. If you want to terminate before the end of the documentation is reached, press Control-X (Hold down the CONTROL key; then type "X".). -30- 12. Send MINIPROP Documentation to Printer (MINIPROP Utilities Choice 6) ------------------------------------------------------------------------ When you make this choice in the MINIPROP Utilities menu, the following instructions will appear on the screen. Please turn on your printer and set it for 80 characters per line and 66 lines per page. Adjust the paper so printing can start within 10 lines from the top of the page. There will be as many as 57 printed lines on each page. Press any key when printer is ready. Just follow these instructions. The documentation is lengthy, so be sure there is plenty of paper in your printer. (The total number of pages will appear at the bottom of the first page.) Printing will begin when you press any key. You may interrupt printing (and return to the MINIPROP Utilities menu) by pressing Control-X. 13. Print Table of Great-Circle Bearings (MINIPROP Utilities Choice 7) ---------------------------------------------------------------------- This choice in the MINIPROP Utilities menu allows you to print a customized table of great-circle bearings (beam headings) from any location (Terminal A) to all of the locations in the MINIPROP atlas. If you have saved a Terminal A default location in the MP.DEF defaults file, you will be asked if you want the bearings to be from the default location. If you answer "N", or if their is no default location in the defaults file, you will be asked to enter the latitude, longitude, and name of Terminal A. Enter these as described in Section 4. You will now be asked for information needed by MINIPROP to optimize the printing of the table by your printer. You will be asked first for the number of lines per page (form length) for your printer with the paper you will be using. (66 lines per page is standard in the U.S.) You will be asked next for the maximum number of characters that your printer will print on one line. Then you will be given the opportunity to send any control codes that may be required to configure your printer. But first turn on your printer and adjust the paper so printing can start 4 to 6 lines from the top of the page. Press any key when ready. Now enter the number of lines per page (form length) for your printer with the paper you will be using. This value must be an integer between 48 and 126. The U.S. standard of 66 lines per page will allow 52 bearings to be printed in each column. The heading and first few entries of a column in the printed table might look like this: PREFIX LOCATION DEG 1A0 S.M.O. of Malta 34 1S Spratly Is. 302 3A Monaco 36 -31- The number of pages required to hold the table of great-circle bearings depends upon the number of characters that your printer can print on one line. A larger number of characters per line will allow a larger number of columns on a page, and fewer pages will be needed to hold the complete table. A table will appear on the screen showing how the maximum number of characters per line affects the number of columns of great-circle bearings that will be printed on each page and the number of pages that will be required. If your printer prints 80 characters on a line, only two columns will fit on a page. If your printer has more than one character width, you will probably want to specify the number of characters corresponding to the narrowest character width. For example, an OKIDATA ML92 printer can print 80 characters per line at 10 characters per inch (cpi), 96 at 12 cpi, and 136 at 17.1 cpi. The best choice is 136; this allows four columns to be printed on each page. Be sure to specify an exact, instead of approximate, number of characters per line so MINIPROP can center the columns correctly on the page. You will next be asked if you want to send control codes to your printer. Control codes are special non-printable codes -- usually numbered 1 through 31 (decimal) -- that tell your printer to change the way it prints. For example, control code 29 must be sent to the ML92 printer in the above example to cause it to switch to 136 characters per line. Control code 27 is often combined with other codes into what are called "escape sequences". Your printer user's manual will tell you what control codes or escape sequences, if any, are needed to set up your printer for the number of characters per line you have specified, to choose a type style, or for another purpose. If you answer "N" (you do not want to send control codes), printing will begin. If you answer "Y" (you want to send control codes), you will be directed to enter the first control code followed by <ENTER> or <RETURN>. Enter the integer decimal value of the first code you want sent. MINIPROP will send the code to your printer and will ask you for another control code. Enter as many codes as are required by your printer. Press only <ENTER> or <RETURN> to tell MINIPROP you are finished. Printing will begin. You may interrupt printing (and return to the MINIPROP Utilities menu) by pressing Control-X. The entries in the printed table will appear in alphabetical order of the prefix. (ASCII alphabetization is used. Numerals precede letters. The numeral 0 precedes the numeral 1.) The bearings are measured in degrees east of north, and are in the range 0 through 359 degrees. However, if Terminal A is at either the north or south pole, the west longitudes (0 through 359 degrees) of the atlas entries are printed in the DEG column. Three asterisks (***) are printed in the DEG column when Terminal A and an atlas entry are co- located or when Terminal A and the atlas entry are antipodes. 14. Convert Version 1 MINIPROP.ATL to Version 2 MP.ATL ------------------------------------------------------ (MINIPROP Utilities Choice 8) ----------------------------- An atlas file containing latitudes and longitudes for all DXCC countries and several additional geographic locations is supplied with this version of MINIPROP. If you already have such an atlas, named MINIPROP.ATL, that you used with MINIPROP version 1, you can use it with version 2 but its internal format must be changed before it can be read by the new version of MINIPROP. This utility will do the conversion for you. -32- MINIPROP will look for your MINIPROP.ATL file on the logged disk drive and in the current directory that should also contain the MINIPROP version 2 files. The new atlas file will be created in the same directory and will be named MP.ATL. The new MP.ATL will occupy somewhat more disk space than does your MINIPROP.ATL file; be sure there is enough space for it on your disk. Any existing file named MP.ATL will be renamed to MPBACKUP.ATL, and any existing file named MPBACKUP.ATL will be erased. Your MINIPROP.ATL file will remain intact. The conversion will abort if your atlas contains more than 800 entries or an invalid latitude or longitude, or if a prefix contains leading, trailing, or embedded spaces, is longer than six characters, or is all-numeric. When you select this utility, you will be asked if you want to proceed with the conversion. Answer "N" if you want to abort the conversion. The atlas will be converted if you answer "Y". The conversion may take a while if you have a large atlas or a slow disk drive. 15. References -------------- 1. National Bureau of Standards, "Ionospheric Radio Propagation", Circular 462, 1948. 2. Davies, K., "Ionospheric Radio Propagation", National Bureau of Standards Monograph 80, 1965. 3. Lucas, D.L., and Haydon, G.W., "Predicting Statistical Performance Indexes for High Frequency Ionospheric Telecommunication Systems", Technical Report ITSA-1, Institute for Telecommunication Sciences and Aeronomy, Environmental Science Services Administration, 1966. 4. Barghausen, A.F., Finney, J.W., Proctor, L.L., and Schultz, L.D., "Predicting Long-Term Operational Parameters of High-Frequency Sky-Wave Telecommunication Systems", Technical Report ERL 110-ITS 78, Institute for Telecommunication Sciences, Environmental Science Services Administration, 1969. 5. National Bureau of Standards, "Handbook for CRPL Ionospheric Predictions Based on Numerical Methods of Mapping", Handbook 90, 1962. 6. Leftin, M., "The Estimation of Maximum Usable Frequencies from World Maps of MUF(ZERO)F2, MUF(4000)F2 and MUF(2000)E", Telecommunications Research and Engineering Report 13, Institute for Telecommunication Sciences, Office of Telecommunications, 1971. 7. Rose, R.B., Martin, J.N., and Levine, P.H., "MINIMUF-3: A Simplified HF MUF Prediction Algorithm", Technical Report 186, Naval Ocean Systems Center, 1978. 8. Rose, R.B., and Martin, J.N., "MINIMUF-3.5: Improved Version of MINIMUF-3, A Simplified HF MUF Prediction Algorithm", Technical Document 201, Naval Ocean Systems Center, 1978. 9. Rose, R.B., "MINIMUF: A Simplified MUF-Predicting Program for Microcomputers", pp. 36-38, QST, December, 1982. -33- 10. Shallon, S.C., "MINIMUF for Polar Paths", p. 48 (Technical Correspondence), QST, October, 1983. 11. Rose, R.B., "MINIMUF Revisited", p. 46 (Technical Correspondence), QST, March, 1984. 12. Fricker, R., "A Microcomputer Program for the Critical Frequency and Height of the F Layer of the Ionosphere", pp. 546-550, Fourth International Conference on Antennas and Propagation, Institution of Electrical Engineers (UK), 1985. 13. Fricker, R., "A Microcomputer Method for Predicting the Field Strengths of HF Broadcast Transmissions", to be published. 14. International Radio Consultative Committee, "CCIR Atlas of ionospheric characteristics", Report 340, International Telecommunication Union, Geneva, 1983. 15. Jacobs, G. and Cohen, T.J., "The Shortwave Propagation Handbook", 2nd ed., CQ Publishing Inc., 1982. 16. "The 1987 ARRL Handbook for the Radio Amateur", 64th ed., American Radio Relay League, 1986. -34-