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.

