APRS�Automatic Packet Reporting System

A Primer

Presented by Dan, W4DOD

APRS History

• APRS was developed in the 1980’s by Bob Bruninga, WA4APR, a senior research engineer at the USNA.
• This early version was used to map high frequency Navy position reports. In 1984, Bruninga developed a more advanced version on a Commodore VIC-20 for reporting the position and status of horses in a 100-mile (160 km) endurance run.

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APRS History

• During the next two years, Bruninga continued to develop the system, which he now called the Connectionless Emergency Traffic System (CETS). Following a series of Federal Emergency Management Agency (FEMA) exercises using CETS, the system was ported to the IBM PC. During the early 1990s, CETS (then known as the Automatic Position Reporting System) continued to evolve into its current form.

APRS History

• As GPS technology became more widely available, 'Position' was replaced with 'Packet' to better describe the more generic capabilities of the system and to emphasize its uses beyond mere position reporting.

APRS Network

• APRS packets are transmitted for all other stations to hear and use. Packet repeaters, called digipeaters, form the backbone of the APRS system, and use store and forward technology to retransmit packets. All stations operate on the same radio channel, and packets move through the network from digipeater to digipeater, propagating outward from their point of origin

Digipeters & IGates

• Digipeaters keep track of the packets they forward for a period of time, thus preventing duplicate packets from being retransmitted. This keeps packets from circulating in endless loops inside the ad-hoc network. Eventually most packets are heard by an APRS Internet Gateway, called an IGate, and the packets are routed on to the Internet APRS backbone (where duplicate packets heard by other IGates are discarded) for display or analysis by other users connected to an APRS-IS server, or on a website designed for the purpose.

Positions/objects/items

• APRS contains a number of packet types including position/object/item, status, messages, queries, weather reports and telemetry. The position/object/item packets contain the latitude and longitude, and a symbol to be displayed on the map, and have many optional fields for altitude, course, speed, radiated power, antenna height above average terrain, antenna gain, and voice operating frequency. Positions of fixed stations are configured in the APRS software. Moving stations (portable or mobile) automatically derive their position information from a GPS receiver connected to the APRS equipment

APRS Beacon Transmitter with GPS Receiver

APRS around the world

Automatic Packet Reporting System

As GPS technology became more widely available, 'Position' was replaced with 'Packet' to better describe the more generic capabilities of the system and to emphasize its uses beyond mere position reporting.

APRS Capabilities

In its simplest implementation, APRS is used to transmit real-time data, information and reports of the exact location of a person or object via a data signal sent over amateur radio frequencies. In addition to real-time position reporting capabilities using attached Global Positioning System receivers, APRS is also capable of transmitting a wide variety of data, including weather reports, short text messages, radio direction finding bearings, telemetry data, short e-mail messages (send only) and storm forecasts. Once transmitted, these reports can be combined with a computer and mapping software to show the transmitted data superimposed with great precision upon a map display

• APRS GLOBAL INTERNET SYSTEM: Although APRS is a local, tactical real-time two-way communications system, all local information is injected into the APRS-IS Internet system so it can be monitored anywhere

APRS on the web

• APRS is world wide linked by K4HG's global FINDU.COM
• APRS.FI is popular,
• as well as OpenAPRS.NET.
• In the U.S., there are approximately 20,000 users on the air at any instant.

APRS Symbols

Some APRS Applications

• Amateur operators use APRS to beacon LIVE weather data to National Weather Service offices nationwide and has been adopted as an "official" technology for the NWS SKYWARN Severe Weather Spotter program.

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APRS used for weather reports

 Using APRS for Hamfest Support�

FOX HUNTING OR DIRECTION FINDING�

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• APRS is an excellent tool for plotting the location of a hidden transmitter, balloon, or interfering signal. APRS will display the intersection of bearing lines from a number of reporting stations and also overlapping signal strength contours if only signal strengths are reported. Finally, APRS includes the Fade-Circle Search and Rescue technique which can be used by a mobile with only an OMNI antenna to locate a hidden transmitter.

FREQUENCY COORDINATION�

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• As more and more digital devices on amateur radio include APRS position information in their routine BEACONS, APRS makes an excellent tool for displaying the topology of radio networks as an aid to frequency coordination.

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STATION TRACKING�

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• Although APRS automatically tracks mobile stations interfaced to GPS, it also easily tracks manual reports. Any station can place an object on their map including them self and within seconds that object appears on all other station di splays.
• In the example of a parade, as each checkpoint comes on line, its position is instantly displayed to all in the net. Whenever a station moves, just updates your position on his map and that movement is transmitted to all other stations.
• To track other event assets, any operator can simply maintain the positions and movements of all assets on their screen, all other displays running APRS software display the same displays. There is also a Tracking command on the display that will cause APRS to keep the map display always centered on a selected object.

Tracking

One of the greatest real-time needs at any special event or emergency is the tracking of key assets. Where is the Event Leader? Where are the emergency vehicles? What’s the weather at various points in the County? Where are the power lines down? Where is the head of the parade? Where are the VIP's? Where is the mobile TV camera? Where is the hurricane?

Position Beacons

• Smart phone apps: IOS & Android
• Byonics TinyTrack4

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Micro Trak (AIO)

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The Micro-Trak AIO (All In One) is a complete, self-contained, rugger, water resistant, portable, 10-watt APRS tracker, including a frequency agile 2-meter transmitter, a TinyTrak3 controller chip, a Byonics GPS2OEM GPS receiver, and an SMA antenna

Kenwood TM-D710GA

Raspberry Pi & APRS�

FIN