1. Introduction
gridloc is a ncurses-based console application that accepts as input
the Longitude and Latitude of a 'home' position on earth and calculates
its Maidenhead Grid Locator, or given the Grid Locator of a position,
calculates the Longitude and Latitude. It can also accept the position
or grid locator of a second remote point on earth and calculate the
bearing and distance from the home location.
If invoked from an X terminal and if
xplanet is installed, it
can also display the position of home/remote locations and the great
circle path graphically, overlayed on the earth's map.
gridloc is a software package released under the GNU General Public License and in the form of source-code files in the C programming language, developed on a UP1000 Alpha computer with SuSE Linux 7.0 installed.
Customization
gridloc is a simple application and it is customized by editing a few
entries in the gridloc.h header file. The main requirement is to enter
a default HOME position string with the longitude and latitude of the
'home' position. Please see the gridloc.h file for more details.
Compilation
To compile just type make in the gridloc source directory. To test run,
type ./gridloc in the gridloc directory to run the binary. Type make
install to copy the gridloc binary to /usr/local/bin and this gridloc.html
manual to /usr/local/lib. Type make uninstall to remove these two files.
Type make clean to remove object files from the source directory and make
distclean to remove all but the files included in the source package.
3. Operation
Start gridloc and enter a position as longitude/latitude in degrees,
minutes and seconds of arc, then type 'g' to calculate the grid
locator. You may type 'd' to enter the default HOME position from
the gridlock.h header file. Please note that blank position fields
are read as a zero value by default. The 'return' key toggles the
East/West and North/South flags ahead of longitude and latitude
entries.
Enter a Maidenhead grid locator (all six characters) and type 'p' to calculate the longitude/latitude of the position. Please note that blank or lower case characters in the locator field will produce erroneous results.
To calculate bearing and distance to a second 'remote' point, enter the longitude/latitude or the grid locator and type 'b'. Both short path and long path bearings (in degrees) and distances (in km) are calculated along a great circle path.
Quit gridloc by typing 'q' or ESC.
4. Keystroke Commands
<d> Enter the default 'Home' position parametrs as specified in the
gridloc.h file into the top row.
<g> Calculate the Maidenhead Grid Locator of a position, given longitude and latitude.
<p> Calculate a position's longitude and latitude given a Maidenhead Grid Locator.
<b> Calculate the bearing and distance to a remote position given its longitude/latitude or grid locator.
<x> Enable the display of home/remote positions and a Great Circle arc using xplanet. This works if gridloc is started from an X terminal.
<q> or ESC Quit gridloc.
Please note that only lower case characters are accepted, to avoid mis- operation when entering grid locator characters in uppercase.
5. Known bugs and annoyances
I have fixed all bugs I have found. However the validation of input
data is not reliable, because of the way ncurses checks entries, for
example integer ranges and regular expressions are checked at exit from
a field. It is then possible to enter invalid data in a field and do
a calculation with erroneous input and output. To be safer, type return
after entering data to activate the ncurses validation functions.
6. Files
gridloc is built from three C source files, a header file and a simple
Makefile. Each file is written, as far as I could, so as to be reusable
and limited to functions of similar or related functionality. All New
Curses display functions are in ncscreen.c. All position/locator
calculations are in calculate.c. The main() function and some flag
and signal handling functions are in main.c. Some customizable values
and color definitions are in gridloc.h.
7. Version History
Version 0.1_beta is the first public beta release of gridloc after
bug-fixing and testing locally.
Version 0.2_beta incorporates a fix for a silly bug that should have been obvious but got away - keystroke command characters typed in the Grid Locator fields would launch the commands, stopping data entry.
Version 0.3 has targets in the Makefile to support make install, uninstall, clean and distclean and it also has this HTML format manual.
Version 0.4 incorporates a fix for a bug that caused incorrect bearing and distance calculations for certain grid locator pairs.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details: