Real
Time Tools inc.
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Range & Bearing Help
Upgrade to the latest version (1.2(5)) About Range & Bearing Range & Bearing is an easy to use calculator that permits you to quickly compute the distance and relative directions between any two points on the earth given their respective Latitude & Longitude. Additional features include:
While considerable effort on the part of Real Time Tools inc. (we are all pilots) has gone into insuring that the Range & Bearing Calculator is the best possible product we can produce it is a technically complex piece of software. As such, it is within the realm of reasonable possibility that, despite extensive testing, there may be some bug we missed. In the event that any deficiency related to design or programming is uncovered in the future, we will use best efforts to provide a corrective release update to all licensed users of Ranger free of charge. Real Time Tools inc. herein disavows any further responsibility and cannot be held liable for any inaccuracies or errors associated with the use of this product. Latitude & Longitude Latitude & Longitude are the two measurements which are used to specify a point on the surface of the Earth. Lines of Longitude run from pole to pole and are each separated by one Degree. There are 360 lines (degrees) of Longitude. They are numbered from 0 to 180 degrees West (clockwise when the earth is viewed straight down from the North Pole) and 0 to 180 degrees East (counter clockwise) from the line of Longitude whose value is zero. This line runs through Greenwich England and is also known as the Prime Meridian. Lines of Latitude run parallel to the Equator. They are numbered 0 to 90 degrees North and 0 to 90 degrees South with 90 degrees being the Latitude at the poles. Latitude and Longitude values are further subdivided into Minutes and Seconds. Each degree contains 60 Minutes and each Minute contains 60 Seconds. One Minute of Latitude (1/60th of a degree) subtends a distance of one Nautical Mile. This is NOT true for lines of Longitude as they converge at the poles and thus the distance between them varies with Latitude. Azimuth An Azimuth is an angle measured with respect to 0 degrees (North). The term Bearing is a more general case and represents a direction measured with respect to some other point (not necessarily North). The Range and Bearing calculator works by computing the bearings between two arbitrary points on the earth and expressing the relative directions between them as a Forward and Back Azimuth measured on the compass. A compass rose measures Azimuth counting clockwise 360 degrees from zero (North) at the top. Thus, a forward azimuth of 90 degrees is due East and the corresponding back azimuth would be 180 degrees or due West. Calculations The calculator works by applying an area of mathematics known as spherical trigonometry. Briefly, it can be understood by imagining a circle divided by two lines which intersect at the center (like cutting a piece of pie). Since the formula for the circumference of a circle is 2 * Pi * Radius, it follows that we can calculate the circumference around a circle subtended by any angle if we know it's radius. The calculator does exactly this by extending the picture into 3 dimensions (a sphere now, not a circle) and computing the angle as measured at the center of the earth between two points on the surface. From this angle we can calculate the Great Circle Distance which is the shortest distance between the two points. A significant part of the trick involves calculating accurately the Cosine of an extremely small angle. The picture is further complicated by the fact that the earth isn't exactly spherical (see Geophysical Survey). Geophysical Survey As mentioned in the section Calculations, the Earth isn't a perfect sphere. It tends to bulge a bit at the equator and flatten at the poles. In order to obtain accurate distance calculations, the calculator has to take this into account. Thus there are actually three pieces of information which are required to specify any point on the Earth; Latitude, Longitude, and a Geophysical Survey datum which quantifies this distortion. Nowadays the existence of the Global Positioning System of satellites (GPS) and the Phase Conjugate mirror left on the moon by the Apollo astronauts have made it possible to survey the planet to unprecedented levels of accuracy. Prior to this, geophysical survey teams had to physically travel to all points and use what would now be considered primitive instruments to arrive at these measurements. The Range & Bearing calculator includes several geophysical survey datum's dating back to some of these earlier ones which the user may select from (see Set Program Defaults). It is interesting to note how little impact on the results there is when switching between them. The accuracy of the older surveys is a significant tribute to the painstaking efforts made by those early survey teams. Station Database In addition to being a generalized input driven calculator, Range & Bearing allows you to accumulate a database of stations which may be quickly recalled at a later time in order to minimize data entry. (see Use the Database). The database allows you to organize your data by category and to associate names and notes with each station you define. For Owners of NavCalc If you own the Aviator's Navigation Calculator - NavCalc, also by Real Time Tools, you can use your Range & Bearing calculator to drive data into this calculator and further simplify the process of flight planning. With the touch of a single button, Range & Bearing will export the current data to NavCalc (see Export Data to NavCalc). When used together, these two calculators provide you with all of the computing power you need to perform the navigational calculations required of any flight plan. Enter a Station Entry of station data is accomplished directly in the top two frames of the calculator's main screen. Simply enter the Degrees, Minutes, and Seconds of both Latitude and Longitude for a station into the three edit boxes provided and indicate via the two sets of radio buttons whether the Latitude is North or South and whether the Longitude is East or West. Note that the default direction for Latitude and Longitude can be preset (see Set Program Defaults). The calculator will respond immediately to each key/pen stroke and update the results in the Range & Bearing frame in the bottom half of the display. Select Distance Units The units of distance displayed in the calculator may be selected via the three radio buttons in the lower half of the display. Note that changing them is immediately reflected in the results displayed. The currently selected distance units are also displayed above the Distance field (NM = Nautical Miles, SM = Statute Miles, KM = Kilometers). Note that the default distance units can also be preset (see Set Program Defaults). Set Program Defaults Program defaults for the calculator can be preset from the Options dialog. Select Edit>Options from the menu or press the  button on the toolbar.
The Options dialog allows you to select:
Use the Database The station database is accessed by pressing one of the  buttons on the calculator's
main screen. Upon entry, any Latitude and Longitude entered from the main screen will be copied into the
Latitude and Longitude fields in order to reduce data entry if you are creating a new entry.
If you are creating a new entry, enter an appropriate name into the Location combo box, select or enter a value in the Category combo box, enter any additional comments you would like to save with the station in the Comment field and press the  button. If you forget to save and just press the
 button, you will be prompted to save the station in the database if it doesn't already
exist.
If you wish to retrieve a station previously saved in the database, simply open the Location combo box and make the desired selection. The remaining fields of the dialog will be automatically loaded with your selection. You can filter which stations appear in the Location combo box's list by first making a selection in the Category combo box. When you are done, pressing will close the dialog and load the data into
the calculator.
You can change the category (or any other field value) assigned to a station by selecting it from the Location combo box, entering or selecting a new value, and pressing again.
To remove a station from the database, select it in the Location combo box and press 
Export Data to NavCalc Range & Bearing has been designed to work with the Aviator's Navigation Calculator - NavCalc, also from Real Time Tools. When NavCalc is installed, the  button on the tool bar will be enabled each time
you change any of the data in the Range & Bearing display. To export the results of any calculation, simply press
this button on the tool bar or select Edit>Export to NavCalc from the menu. The button (and the menu item)
will then disable to indicate the data was successfully exported until the next time you update the display.
Obtain a Valid License Range & Bearing is made available as shareware. This means that you have a limited use (30 day) license during which time the product is fully functional in order that you may evaluate it. After the trial period is over Range & Bearing will cease to operate unless you obtain a valid end user license. You can purchase a license at any time at Handango, or by visiting Real Time Tools inc. Please note that you will need to provide your Product Code number which is available from the Licensing dialog. This dialog is available to unlicensed users when the calculator first starts up. The latest version (1.2(6)) corrects an error that prevented station descriptions from wrapping properly. It is not necessary to uninstall earlier versions of Range and Bearing when upgrading to a new release. During the installation process warnings will pop up advising that certain files will be overwritten. These may be safely overwritten without loss of data. Range & Bearing allows you to uninstall and reinstall to your Pocket-PC without having to re-license. Note, however that an uninstall will remove all files including the station database. If you wish to save this file for a later reinstallation you must backup the file Ranger.ddb from the Pocket-PC's Range & Bearing installation directory.
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