Grid Loc -- A Palm Program for Computing Grid Squares, Bearing, and Distance
by John P. Toscano, WØJT (ex-KBØZEV)

The program Grid Loc runs on the Palm Pilot and compatible PDA's.  It allows you to convert back and forth between Latitude and Longitude (in various formats) and Maidenhead Grid Squares.  You can enter Latitude and Longitude in either decimal degrees; degrees and minutes; or degrees, minutes, and seconds.  You can enter Maidenhead Grid Squares in either 4-digit form (for example, EN34) or 6-digit form (for example, EN34js).

It also computes the beam heading (direction to point your antennas), and distance, from your Amateur Radio Station to another station at a known location.

The bearing angle is shown in degrees.  The distance between stations is shown in either miles or kilometers.  The distance and bearing are according to the Great Circle path between the two stations, which is the shortest path between them.  You may be surprised to know that two stations located at exactly the same latitude would not necessarily point their antennas due East and due West for the most direct path between them!  This program gives the true bearing between stations.

The program automatically remembers the last pair of locations ("My Location" and "To Location") that were entered, and the distance units (miles or kilometers) that were last selected.

This is the main screen of the application.  The first time it is run, it defaults to a source location at the QTH of KBØZEV (now WØJT) in Apple Valley, MN, and a destination location at the QTH of KMØT in Sioux Center, IA.  Mike and I have had a number of QSO's on the lower 6 VHF/UHF bands (50 - 1300 MHz) from these locations, with "armchair copy quality".  Don't worry, however, if those locations are of no interest to you.  As soon as you enter different locations into either the source or destination sections of the screen, those new locations will become the new defaults the next time you start the program.

If you prefer your distances in kilometers, simply tap on the menu button or title bar, and on the Settings menu, select "Show Kilometers".  The distance will be recalculated and the display will be updated automatically.  Until or unless you change it, all future distance readings will be in the new units.

The only other menu choice at the present time is the "Help About" screen.  I may be adding new features in the future, and they may be accessed from the menu structure. Note that the email address shown on the help screen is no longer valid. I really do need to put out an updated version!

To use a new location, you simply change the location's coordinates or grid square, and everything else is calculated for you.  The screen shots to the left show a new grid square has been entered in the "To Location" area of the screen, but no new calculations have been done because editing has not been finished.  To finish editing and update the entire display, you can either tap on a different field that you intend to edit, or tap on the Calc button.  (I just worked a station in this grid on 08/27/2001 on 2 meters and 70 cm, thanks to a band opening!)

To download the program, there are up to three files needed.

The first file is GridLocator.prc, which is the Palm application program itself.  You always need to download this file.

The second file is mathlib.prc, which is a widely used mathematics library.  If you have any other mathematically oriented program on your Palm, there is a good chance you already have this library file installed.  If not, then download this copy and install it along with the main program listed above.

The third file is NSBRuntime.prc, which is the "run-time library" for the NS Basic language that was used to develop this program.  You only need one copy of this runtime library for any NS Basic programs that you install on your Palm.  But there is a fair chance that this will be the first such program you install.  (I'm working to change that, but writing new software takes some time!)  So if you don't have a copy, you will need this one also.

Questions or comments should be directed to me at my email address as shown on
Good hunting on the bands!