The Automatic Packet Reporting System (APRS) combines Global Positioning (GPS), Amateur Packet Radio and computer street mapping. Most GPS receivers output serial data (a few do not have a connector to output the data, be careful what you buy) in a specific format called the NMEA Data standard. This serial data is accepted by some Amateur Radio TNC's (Terminal Node Controller), and processed for transmission by radio. The frequency used in Wisconsin for APRS transmissions is 144.390 MHz. The data is then received by another radio, processed back through another TNC and run into a computer. Several software programs are available to display the information on screen. Some software packages use commercial mapping programs that cover the entire US down to street level.
APRS packet has become very popular across the country. There are a large number of HAMS operating APRS in the SE Wisconsin and Northern Illinois area. APRS relies on fixed stations to relay data throughout the system, or Network. Many HAMS operate a "Home Relay" station, a TNC and radio on the APRS frequency (144.390Mhz) that responds to unproto packets (packets simply addressed to "RELAY"). There are also major node, or WIDE stations located on towers or high buildings that forward data over long distances, or from State to State. The network infrastructure allows a mobile station running at low power to be heard and "relayed" throughout the network to all listening stations.
So, what good is all this, what is it for?
In South East Wisconsin, we have built an APRS network for support of our ARES (Amateur Radio Emergency Service) work, and to support Bike and Run/Walk community events. A net control station can continuously know simply by looking at a computer screen, exactly where all of the moving vehicles involved with an event are located. The event sponsors can see the progress of their event live, can see the relationships of the current positions, and evaluate the redeployment of these resources.
We are also working with the local National Weather Service (NWS) office to tie them into the network. This will allow instant VISUAL reporting and tracking of severe weather SKYWARN information to the NWS. The NWS is very interested in the capabilities of HAMS and APRS.
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