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Ham Radio Version 3.2 (Chestnut CD-ROMs)(1993).ISO
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1990-02-27
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236 lines
The DXer
By WA6JOO
19279 Santa Ana Ave
Bloomington, CA 92316
(c)1990
1. Introduction
The DXer concentrates several functions of interest to the
serious DXer into one (hopefully) easy-to-use program.
A: Bearing and Distance from Transmitter to Receiver.
B: Sunrise, Noon, Sunset times for any location
C: Maximum Useable Frequency and Frequency of Optimum
Traffic between any two locations.
D: A listing of all locations sharing a common terminator
line (Gray Line).
E: Prints custom bearing/distance charts for any location.
F: A grid locator function using the Maidenhead coordinate
system.
E: A complete data base of all ARRL countries as well as
other locations around the world. The data base shows
latitude, longitude, continent and CQ zone of each
location. Entries may be easily added, deleted or edited.
2. SYSTEM REQUIREMENTS
IBM PC, XT, AT or close clone with 384k memory. A math
coprocessor is highly recommended although not required. If
you have no coprocessor, be prepared to wait a while for
some calculations, especially for the Gray Line.
Monochrome, CGA, EGA, VGA monitor. You may have some
readability difficulties if you use a composite b/w monitor
with a color board, since there is no way to disable color
with this combination.
One 360K floppy drive. All data is kept in memory so,
except when loading or modifing the data base, there is no
real advantage to a hard disk. If you have one, by all
means use it.
This program was developed on an 8MHz IBM AT and a 10MHz
clone and runs correctly on both machines. There is no
machine specific code in the program so it should run on any
100% BIOS compatible.
A Printer is not required but, if available, many of the
data tables may be printed.
3. GENERAL
The program is written in MicroSoft QuickBasic 4.0/4.5 and
contains approximately 3000 lines of code. The algorithms used in
some of the calculations were extracted from many sources and I make
no claim of originality for them except for the implementation in
QuickBasic.
The program was written for my own use and to become proficient
in the QuickBasic language and represents literally hundreds of hours
of programming time. I am releasing the program into the public
domain for individual use and enjoyment only! Permission for any
commercial use is expressly denied. If you find this program to be
useful, a small (10$ or so) donation would be appreciated, however, if
you choose not to make a donation, I doubt if I'll lose any sleep
over it.
4. PROGRAM DESCRIPTION
The program is completely menu driven and is generally self
explanatory. A couple of items to remember:
a: When entering latitudes and longitudes, use decimal degrees,
not dd,mm,ss format. Preceed latitudes south of the equator with
a minus(-) sign. Preceed longitudes east of Greenwich with a
minus(-) sign.
b: When running the program for the first time, you will be
prompted to create a Configuration file. This file contains your
home latitude and longitude and the formfeed code for your
printer. Once the file has been created, it may be changed at any
time from the FILE UTILITIES menu.
If no printer is available, the BEARING TABLE function will not
show on the main menu and the print function will not show on the
PROPAGATION FORECAST and SUNRISE-SUNSET selections.
c: Two copies of the database file and the configuration file
are maintained by the program. If the main file is damaged,
simply go into DOS and rename the main file to some other name
then rename the backup file to the primary name. The program
will create a new backup file.
d: When running the program, the active keys are shown at the
bottom of the screen.
e: A moderate amount of error checking is done on any user input
although some types of errors are impossible to trap. If you
make a mistake on entry, use the backspace key to edit.
f: From any menu, use the up and down cursor keys to move the
highlite bar. Press the Enter key to select.
g: The Escape key will always back up to the previous logical
page.
h. The program reads the system clock for local time and
converts to UTC as required for calculations. If you don't have
a real-time clock be sure to set your system clock using the DOS
Time and Date functions before running the DXer. The Program
recognizes Daylight Savings Time and European Summer Time. DST
begins on the first Sunday in April and Ends on the last Sunday
in October. EST begins on the last Sunday in March and ends on
the last Sunday in September. If your location does not observe
one of these time changes, enter "N" at the appropiate prompt
when creating your Config. file. If some other time schedule is
observed at your QTH, you will have to make your own correction
by reseting your system clock.
5. MENU DESCRIPTIONS
A: BEARING-DISTANCE
Shows both short and long path bearings and distances from a
transmitter location (most often your home QTH) and a receiver
location. The receiver location may be specified by prefix,
latitude/longitude, grid square, or chosen from the data base.
When selecting by prefix, all locations with a common prefix
will be shown.
B: PROPAGATION FORECAST
Transmitter and receiver locations are selected as above.
MUF calculations are by the MiniMUF '85 algorithm with an initial
hop length of 4000km. Actual hop length and number of hops are
changed by the program so that the path between transmitter and
receiver is an even number of hops. Since a 4000km hop length is
very difficult to achieve due to the extremely low radiation
angle required, the program will not extend the hop length beyond
4000km for calculations.
The FOT calculations are based on the calculated MUF with
corrections based on absolute sunspot number, UTC time, and
season. FOT will generally be somewhere between 80 and 90% of
MUF.
The calculated values from the program have been checked
against the output from several other programs avaliable in the
public domain as well as the propagation curves published monthly
in QST. The plotted curves are in general agreement although I
have not observed point by point agreement between any two
programs. The output from The DXer seems to agree reasonably
well with observed propagation conditions on the bands.
Since the ionosphere has a long time constant, a 5 to 10 day
smoothed (average) solar flux number will generally give more
believable numbers. No allowance is made for disturbed
conditions since I have yet to see an algorithm to do this. If I
ever find one, I will certainly add it to the program.
The radial MUF calculations are from a transmitter location
to receiver locations at a given distance from the transmitter on
bearings from 0 to 350 degrees from the transmitter. Maximum
number of hops is 5 (20000km).
C: SUNRISE-SUNSET TABLE
Calculates sunrise, noon, and sunset times for the selected
location over a one month period. The first calculation is
always for the current month.
The noon calculation is handy for determining true north
from any QTH since a shadow will point to true north at true noon
at any location in the northern hemisphere.
D: GRAY LINE
Calculates sunrise and sunset for all locations in the data
base and displays those locations whose sunrise or sunset is
within plus or minus one-half hour of the transmitter location
sunrise or sunset.
E: BEARING TABLE
If you have a printer this routine will print a custom
bearing-distance table from any location to all locations in the
data base. The printout will be in Prefix order and includes all
countries on the ARRL DXCC countries list as well as any other
location that you include in the data base.
F: GRID LOCATOR
This function is mainly useful by you VHF types out there.
Grid coordinates use the Maidenhead system as described in the
RSGB VHF handbook. You may identify a grid square by entering
the latitude and longitude or may enter the grad square and
calculate latitude and longitude. If the entered coordinates
should fall on the dividing line between two or more squares, the
identification will default to the square to the north and/or
west of the entered location.
G: FILE UTILITIES
Allows you to maintain the data base. You may add new
records, delete records, or edit existing records. If you change
the data base in any way, the unchanged version is saved as the
backup file on disk. The data base is maintained in order sorted
by prefix.
This function also allows creation of the configuration
file. The config file contains your home latitude and longitude
and your printer formfeed code.
Well, that's about it. I've pretty well debugged the code but there
is no such thing as a bug free program if it contains more than a few
lines of code. If you find any significant bugs, drop me a note on
the back of a QSL and I'll fix it.