If you have started using APRS, you may have wondered how to sort out all the information available on your display. This month we'll go over some examples of different screen displays.
To review, there are several single-key commands to give you various text displays:
P shows the POSITION screen. This is a list of all stations' position
L shows the LIST of status (non-position) packets.
D shows the DIGIPEATER list, the paths of all stations heard.
B shows any current BULLETINS that stations may have sent.
H shows the HEARD page, a list of hourly statistics from each station.
F1 gives HELP! Press F1 then H for a quick summary of one-letter commands.
Pressing the SPACE bar redraws the current map.
Pressing the HOME key redraws the current map centered on the cursor location.
Pressing PAGE UP or PAGE DOWN zooms in or out centered on the cursor location.
Q is for QUIT.
Now let's see how to view different map screens. The following screens are part of the Wisconsin "maplist" which is not available on the generic download of APRS from the TAPR web site. (See the April 1999 BSSS or visit the WJ9H web site to see how to get Wisconsin files.) Once you've launched APRS, you will need to load the Wisconsin map list by pressing M (Maps), C (Config), C (Change map list), and entering "WI" then <Enter>. Move the cursor over Wisconsin and press <Page Down> to zoom in. Here's a typical view of southeast Wisconsin as received in Madison.
Notice that some stations overlap each other, making it difficult to see them all. If we cursored over to Waukesha County and continued zooming in, we would see this:
At this range, it is easier to view the stations. Note that digipeaters are represented by green stars, weather stations are blue circles, and mobiles show up as vehicle icons. Also visible in this view is N9UUR's internet gateway, shown by a "G." Now let's zoom out and pick up some of the activity in northern Illinois and eastern Iowa.
Now stations in metropolitan areas really overlap each other. However, to single out one station, simply cursor over its icon and press <Enter>. At the bottom of the screen you will see its position and status, plus a small histogram showing how many times you've received packets from that station each hour. If the map is centered on your station, the box in the upper left corner of the screen shows the distance and direction to the "hooked" station. Press <Enter> again to "unhook" the station.
If you'd like to display just a certain type of station and ignore the others, reach for the J (Just) key. Press J (Just), M (Mobiles) to see only mobile stations.
You're seeing only stations with GPS trackers. Some show up as cars, some as jeeps or vans. If the mobile is programmed to use a particular GPS sentence showing course and speed, APRS will plot a vector over the icon showing that information. If you have the "dead-reckoning" option enabled in APRS, the program will estimate the vehicle's future position in absence of any updated GPS positions.
Here is what a weather-only display looks like. Press J (Just), W (Weather).
There are several different ways to display the weather information
transmitted from each station. The default is the station's callsign. In
figure 5, I've chosen the Temperature/Rainfall option. Other options are:
To change the weather displays, press W (Weather), C (Calls) and follow the sub-menus. You can display ALL the weather information from each station by pressing the N (Next) key, which cycles through each weather-reporting station and displays its information at the top and bottom of the screen.
One weather station, KB9TJQ, has an extra circle around its icon. That signifies a National Weather Service station; in this case, the NWS/Sullivan office has an amateur station. It runs the Windows version of APRS and can monitor the area weather-reporting stations, both automated and those entering data manually.
You can use the J (Just) command to display just digipeaters, or any other single type of station. To see all the stations again, press J (Just), A (All).
Next month we'll tackle the basics of setting up an automated APRS weather station and a GPS tracker. In the meantime, here are a few web pages to check out for more information on APRS. Keep those TNCs on 144.39 MHz!
WJ9H's web site: www.qsl.net/wj9h
N9UUR's web site: www.execpc.com/~N9UUR
Latest APRSdos version (Tucson Amateur Packet Radio): www.tapr.org