file: propprgm.txt updated January 4, 1995 Reprinted from the 1995 ARRL Handbook for Radio Amateurs, pages 2.18 and 2.19 Copyright 1994 American Radio Relay League, Inc. All rights reserved MUF Prediction on the Home Computer Like predicting the weather, predicting propagation -- even with the best computer software available -- is not an exact science. The processes occurring as a signal is propagated from one point on the Earth to another are enormously complicated, and subject to an incredible number of variables. Experience and a knowledge of propagation conditions (as related to solar activity) are needed when you actually get on the air to check out the bands. Keep in mind, too, that ordinary computer programs are written mainly to calculate propagation for great-circle paths via the F layer. Scatter, skew-path, auroral and other such propagation modes may provide contacts when computer predictions indicate no contacts are possible. Brief information about prediction programs for the IBM PC and compatible computers follows. The programs can be divided roughly into two categories. The first includes programs best suited for quick, on-the-fly predictions. Programs such as MINIMUF, IONSOUND or MINIPROP are excellent tools for assessing what bands are likely to be open in the near future, usually using recent propagation indices broadcast on WWV as data input -- to see, for example, whether 21 MHz is likely to be open tomorrow morning on the path from Kansas City to Berlin, given a solar flux averaging 95 over the last several days. The second category includes programs designed for long-term analysis and station planning. These programs require more investment in computer hardware, and will often take a considerable period of time to do their complex calculations. Most long-term planning programs benefit greatly from the use of a math coprocessor, although most of them will run, even if slowly, without a math processor in the system. ASAPS and IONCAP and CAPMAN typify this category of heavy-duty propagation programs. Table 21-7 summarizes the features and attributes of these programs. Each program is copyrighted unless otherwise indicated. ASAPS V2.2 ASAPS, for Advanced Stand-Alone Prediction System, was developed in Australia. It rivals IONCAP (see below) in its analysis capability but performs calculations in significantly less time. It is also interactive with the user; transmit power levels, antennas and other parameters may be changed and the new results viewed almost instantly without further menu entries. Available from: IPS Radio and Space Services, PO Box 1548, Chatswood NSW 1057, Australia; or through Jacques d'Avignon, VE3VIA, 965 Lincoln Dr, Kingston, ON K7M 4Z3, Canada. IONCAP, Version PC.27 IONCAP, short for IONospheric Communications Analysis and Prediction, was written by an agency of the US government. This program is considered by many amateurs and professionals alike as the most comprehensive and best HF prediction program available. The program has been under development for almost 30 years, and was ported to PCs from a mainframe environment. It offers no menu; rather, an ASCII input file containing instructions and data must be prepared for program execution. This is public-domain software. (CAUTION: Under federal law, this software cannot be given to non-US citizens without export approval.) Available from: National Technical Information Service, 5285 Port Royal Rd, Springfield, VA 22161. IONSOUND HDX, IONSOUND, IONSOUND PRO There are now three versions of IONSOUND, at price levels from $15 to $75. The low- end IONSOUND HDX program is tailored specifically for the locations shown in the "How's DX" column in QST. It provides calculated data that one would not expect from a program of its price class. Its bigger brothers of course provide more features * IONSOUND PRO is the top of the line model. Graphs present mode chirp plots (frequency versus delay time versus intensity), much as an ionsonde oblique-incidence sounder might produce. For each path calculation, the user must first answer several screens of questions, such as noise environment at the terminal points, receiver bandwidth, required S/N ratio, order of layer modes and so on. Available from Skywave Technologies, 17 Pine Knoll Rd, Lexington, MA 02173. MINIMUF, Version 3.5 Written in BASIC, this was the first prediction program to become available for use on home computers. The program was published in Dec 1982 QST (R. B. Rose, "MINIMUF, A Simplified MUF-Prediction Program for Microcomputers," pp 36-38). This is public- domain software that has been customized by many subsequent software writers. The core algorithm's accuracy suffers outside the range from 250 to 6000 miles. MINIMUF calculations do not consider the E region, further limiting its accuracy. MINIPROP PLUS, Version 2.0 MINIPROP has undergone several revisions since it first appeared. It was written primarily for the amateur community, and has an excellent user interface, with great graphics. In addition to the customary propagation data, it provides sunrise-sunset and gray-line information, along with a world map showing either long- or short-path propagation graphically. MINIPROP PLUS also produces a unique "DX Compass" showing the MUF in 12 azimuth directions for a given time of day. Available from Sheldon C. Shallon, W6EL, 11058 Queensland St, Los Angeles, CA 90034-3029. Application Tips Because of the lag in F-layer response to a rapid increase in solar activity, it is best to use either a 5-, 15- or 90-day running average of the 2800-MHz (10.7-cm) solar flux for prediction calculations. The type of application determines which is beset. The 5-day mean is a short-term dynamic input; the 90-day mean is appropriate for long-term planning. The ultimate test, of course, of a prediction program is to get on the air and listen to the signals arriving from the part of the world you just modeled! The members and HQ staff would like to thank the following people for their contributions to this information file: N6BV Send any additional information or changes to mtracy@arrl.org. 73 from ARRL HQ.