North American Overlay Mapping
The APRS Interface
To use the APRS interface, select one of the maps, then click on the 'APRS' button, located to the top right of the upper toolbar. An internet connection is also required, as the APRS interface aquires its data from the FindU server on the world wide web. The interface has 5 sections: All, Plot, Line, Breadcrumb, and List. Each is detailed below:
The 'All' section displays icons for all current stations in the FindU database with positions within the borders of the current map. Extra options let you turn callsigns on and off, or change the length of time that is used to determine which callsigns will be displayed. To load the icons, click the 'Load' button once only. After a short wait, the icon overlay will display over the current map. Use the 'Hide' and 'Show' buttons to hide and show a currently loaded overlay; if no overlay has been loaded, these buttons will appear to do nothing, apart from giving their usual audio feedback when clicked. Note that the 'All' section can not be used with the two Overview maps, as the amount of data and hence icons on display would be excessive.
The 'Plot' section is very similar to the 'All' section; the difference being that you can specify callsigns to be displayed. This is useful if you wish to plot the position of a small number of icons, and will result in a less crowded map. Multiple calls are allowed, separated with commas. You can also use wildcards i.e. k4hg* if you are not sure which 'SID' suffix a call may be using, or where you want to display calls within a range i.e. cw* to show all CWOP weather stations.
The 'Line' section is very similar to the 'Plot' section; the difference being that instead of plotting just one square showing the callsign's latest position, it will draw a square for each recorded position within the time period specified, and connect the points with a line, thus showing the recent path for that station. Multiple calls are allowed, separated with commas, but not wildcards.
The 'Breadcrumb' section is very similar to the 'Line' section; it will draw a square for each recorded position within the time period specified, but does not connect the points with a line. The current position has the callsign attached. No wildcards allowed.
Below the 'Breadcrumb' section is a link that will open a new browser with a list of all stations with positions within the borders of the current map for the last 10 days. This can be useful to spot specific callsigns or idents that would otherwise be lost in a crowded display. As you may imagine, these lists can be very long, so will take a while to generate and load over a slow Internet connection - please be patient.
For more information about the FindU server, click here. A full list of FindU commands can be found here. For a general guide to APRS, try a Google search.