APRS Introduction The DOS version of APRS
(Automatic Position Reporting System) was created by
Bob Bruninga. Later on, versions
for other operating systems came along written by
Mark Sproul, Keith Sproul,
Brent Hildebrand, and
Steve Dimse to facilitate:
- Tracking of weather events
- Tracking Automobiles, Airplanes, Balloons, and Satellites
- Relaying of real time data such as races, emergency service, public
events
- RDF Locating of Problematic Transmitters
- Observing HF Band Conditions
This page favors the Windows APRS version and is meant to serve as a
semi-technical overview of WinAPRS
Until now, most packet applications have been text based. These
applications have been accessed by typing, and displayed information in
a textual manner. They also required the user to have knowledge of the
local network, and actually connect to a server or bbs to get
information.
APRS is different. With this system, users can
operate entirely hands off, and the information is presented in an easy to
understand format, overlayed onto maps of local areas. Maps on APRS do not
have to represent geographic areas. Maps can be created that define charts
and tables - even chessboards. Any user in the network can take control of
an object and update it's position. Imagine a chart listing people in a
shelter, supplies, or resources. Any of these resources can be moved
graphically to any other location by any station in the net. The local EOC
supply truck doesn't have a GPS? No problem, just create one on the map, and
manually move it as you talk to him on the radio. His position will be shown
on every APRS screen in the area in a matter of seconds.
APRS has all the symbols for weather conditions, and each weather
condition can be placed on the map for all to see. Information is
transmitted instantly to all other APRS stations. In the event that a
station does not hear this information, it will be transmitted 3 times in
the first 60 seconds, 3 times in the next 10 minutes, and 3 more times the
next hour. New stations coming online can query other stations for known
information, such as the locations of shelters, and hospitals.
Another way that differentiates APRS from other packet programs is it's
ability to pick information off the air passively. A very few stations can
get information out to several hundred stations with only one or two
transmissions. Other packet messaging systems require that each station
receive it's own unique copy of any given message. This could lead to 100's
of transmissions to distribute the same information aprs could accomplish in
one single transmission!
The APRS network infrastructure is generic by nature... all stations are
on the same frequency, all relay points are named identically. This
universal generic network allows operators unfamiliar with the "lay of the
land" to hit the ground running. The maps available vary in detail from the
entire world right down to the tables at a hamfest.
In the past several years, specialized hardware has been created just for
APRS. There are special APRS microphones which transmit your position at the
end of each transmission like a "roger beep", specialized TNCs just for
transmitting weather, and most importantly, APRS is so popular that it has
reduced the cost of hardware for the average user. Whereas a "one size fits
all" TNC used to cost $120 to $150, you can now buy a transmit only TNC for
$25!
