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.