EOSS Grid Calculator Version 3

Nick Hanks, N�LP, has updated his grid calculator to provide several new features. However the latest incarnation of that program is only available directly from Nick. Contact him and he will make arrangements for you to obtain a copy.

Here is an older version of Grid Calc:

The calculator provides EOSS grid coordinates quickly when a position�s lat/long is entered, or the user can reverse this operation determining their latitude and longitude from a grid position.

A new feature allows the calculator to receive GPS data continuously and automatically update the user�s grid position.

The calculator may prove helpful if you run off the edge of the map, or if you�re in a location that lacks any recognizable geographic features that relate back to the map.


Operation is pretty intuitive. The coordinates of the reference grid point (its lat/long and grid coordinates) are entered, and then the lat/long of a position (which could be yours in the field) are entered. The program can then calculate the gird coordinates of that position. Figure 1 shows the calculator loaded with actual data.

Figure 1  EOSS Grid Calculator showing a reference grid centered on Last Chance, CO and the grid position for the Flagler, CO exit on I-70

The calculation of a point�s lat/long given its grid position function is activated by the radio button in the "Calculation" frame. In addition, the format of the calculated lat/long data can be set with the radio buttons in the Position Format frame. The reference grid data can be stored in a file and then recalled quickly with the Load Previous button or the from the Open selection under the File menu..

Automatic Update Feature

The new automatic GPS update capability is activated by selecting the radio button labeled �Auto Grid Position.� The GPS must be set to send NMEA data strings at 4800 bits per second (Most GPS�s that have an external output jack send at 4800 bps.) The GPS is then connected to the computer with a serial cable. The Comm Port menu item selects the comm port (i.e., the serial port) on the computer that you wish to use. Once reference grid data is loaded, the Grid Position windows will update about once every 2-3 seconds. A dot beside Auto Grid Position will change from red to green and back as data is received from the GPS. The Calculate button disappears in this mode and is replaced by a window indicating the current magnetic declination for the current location.

A truncated view of the data from the GPS can be seen by selecting the NMEA Data choice under the Windows menu item. The calculator uses the $GPRMC NMEA sentence for its updates. In addition, your computer's clock can be updated using received GPS data by clicking on the SetSysTime menu item or the clock face icon.

Another new feature is the ability to choose a grid reference point from a list and have the lat/long of the point load automatically. This feature is accessed through the File menu and the Open Location List item. The Read-me file distributed with the calculator explains how to modify the list. That file also includes other useful information on the calculator's operation.

There also two other choices under the Windows menu, grid name and range/bearing, which may prove useful.

Downloading the grid calculator

Due to the need to load the comm port software controls (which are from Microsoft) only a full installation is available.

In the full installation, the setup wizard will create a directory containing the .exe file, a readme file, some of the .ocx and .dll files, the first Ref_Gird.txt file, and the Locations.txt file. To install, unzip the GridCalc32.zip file and click on setup.exe. Be sure to take a look at the read.me file.

Download  GridCalc33.zip ~ 2.4 Mbytes.
This full installation file uses a setup wizard which adds item to Start/Programs list. The ReadMe file is included.

Visual Basic Run Time Files

If you don't have the Visual Basic V 6.0 runtime files then download a copy of Vbrun60sp5.exe