Automatic Position Reporting System
Encyclopedia
Automatic Packet Reporting System (APRS) is an amateur radio
-based system for real time tactical digital communications of information of immediate value in the local area. In addition, all such data is ingested into the APRS Internet system (APRS-IS) and distributed globally for ubiquitous and immediate access. Along with messages, alerts, announcements and bulletins, the most visible aspect of APRS is its map display. Anyone may place any object or information on his or her map, and it is distributed to all maps of all users in the local RF network or monitoring the area via the Internet. Any station, radio or object that has an attached GPS is automatically tracked. Other prominent map features are weather stations, alerts and objects and other map-related amateur radio volunteer activities including Search and Rescue and signal direction finding.
APRS has been developed since the late 1980s by Bob Bruninga, callsign WB4APR, currently a senior research engineer at the United States Naval Academy
. He
still maintains the main APRS website. The acronym "APRS" was derived from his callsign.
. Rather than using connected data streams where stations connect to each other and packets are acknowledged and retransmitted if lost, APRS operates entirely in an unconnected broadcast fashion, using unnumbered AX.25
frames.
APRS packets are transmitted for all other stations to hear and use. Packet repeater
s, 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. All stations within radio range of each digipeater receive the packet. At each digipeater, the packet path is changed. The packet will only be repeated through a certain number of digipeaters -or hops- depending upon the all important "PATH" setting. 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. While it would seem that using unconnected and unnumbered packets without acknowledgment and retransmission on a shared and sometimes congested channel would result in poor reliability due to a packet being lost, this is not the case due to the fact that the packets are transmitted (broadcast) to everyone, and multiplied many times over by each digipeater. This means that all digipeaters and stations in range get a copy, and then proceed to broadcast it to all other digipeaters and stations within their range. The end result is that packets are multiplied more than they are lost. Therefore, packets can sometimes be heard some distance from the originating station. Packets can be digipeated tens of kilometers or even hundreds of kilometers depending on the height and range of the digipeaters in the area.
When a packet is transmitted, it is duplicated many times as it radiates out, taking all available paths simultaneously, until the number of "hops" allowed by the path setting is consumed.
The map display uses these fields to plot communication range of all participants and facilitate the ability to contact users during both routine and emergency situations. Each position/object packet can use any of several hundred different symbols. Position/objects can also contain weather information or can be any number of dozens of standardized weather symbols. Each symbol on an APRS map can display many attributes discriminated either by color or other technique. These attributes are:
All APRS messages are delivered live in real-time to on-line recipients. Messages are not stored and forwarded, but retried until timed out. The delivery of these messages is global, since the APRS-IS distributes all packets to all other igates in the world and those that are messages will actually go back to RF via any IGate that is near the intended recipient.
A special case message can be sent to EMAIL and these messages are pulled off the real-time APRS-IS by the WU2Z Email engine and wrapped into a standard Internet Email protocol and forwarded into regular internet email.
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.
While the map plotting is the most visible feature of APRS, the text messaging capabilities and local information distribution capabilities combined with the robust network should not be overlooked; the New Jersey Office of Emergency Management has an extensive network of APRS stations to allow text messaging between all of the county Emergency Operating Centers in the event of the failure of conventional communications.
protocol using 1200 bit/s Bell 202
AFSK on frequencies
located within the 2 meter amateur band.
Sample APRS VHF frequencies
An extensive digital repeater, or "digipeater" network provides transport for APRS packets on these frequencies. Internet
gateway stations (IGates) connect the on-air APRS network to the APRS Internet System (APRS-IS), which serves as a worldwide, high-bandwidth backbone for APRS data. Stations can tap into this stream directly, and a number of databases connected to the APRS-IS allow web-based access to the data as well as more advanced data-mining capabilities. A number of low-earth orbiting
satellites, including the International Space Station
, are capable of relaying APRS data.
Reporting stations use a method of routing called a "path" to broadcast the information through a network. In a typical packet network, a station would use a path of known stations such as "via n8xxx,n8ary." This causes the packet to be repeated through the two stations before it stops. In APRS, generic callsigns are assigned to repeater stations to allow a more automatic operation.
The HamHUD integrates a display for viewing the position of other stations and weather reports, and a means of sending and receiving APRS messages, and an interface for a GPS receiver. It started out in 1997 as a homebrew device, but more recently, kits have been available from time to time. It connects to a TNC which is in turn connected to a radio. The Alinco DR-135T is popular as the internally mounted T2-135 can be used with it, reducing the number of items that need to be connected together. SmartBeaconing was developed for the HamHUD by Tony Arnerich and Steve Bragg. It varies the beacon rate based on speed, and adds corner pegging. SmartBeaconing has been adopted by the TinyTrak and OpenTracker series of trackers, in a software update for the Kenwood TM-D710, and in the TH-D72 from its release.
The RTrak combined an OpenTracker 1+ and a GPS receiver along with a low power transmitter in one package. The original units produced 500 mW, but the current version puts out 350 mW.
Byonics has introduced an all-in-one device combining a GPS receiver, TinyTrak controller and synthesized 2m radio called the Micro Trak AIO which requires no assembly by the user. Other products include; TinyTrack4, Microtrak line, and tinytrack3.
ArgentData now has a 5-Watt VHF Transceiver with Integrated Tracker2 in one compact package. With a non-display GPS receiver connected, the T2-301 can be used as a tracker. With compatible display-type GPS receiver, received position reports can be output as waypoints. With a Garmin Nuvi 350 GPS receiver connected, it can send and receive APRS messages as well as display other stations as waypoints. The Nuvi 350 can be used this way with a stand-alone Tracker 2 (OT2m) or connected to a T2-135 which mounts in an Alinco DR-135 radio. The T2-301 can also be used as a stand-alone digipeater. Other products include; The New USB Tracker, and OpenTracker+.
The APRS SkyTracker is an APRS Beacon at 144.800Mhz which includes a 8W RF Transmitter, programmable PIC & u-bloc GPS receiver all on one 72x56mm PCB.
The BigRedBee GPS Transmitter is the smallest 2 meter frequency agile completely integrated APRS transmitter available. Output power is 6 watts from a supply voltage of just 7.5 volts. It also features on-board data recording that can be downloaded for later and viewing via Google Earth. A low power 70 cm version is also available.
computer in 1982. 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 miles (160.9 km) endurance run. 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, now known as the Automatic Position Reporting System, continued to evolve into its current form. 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 FireNet is an Internet-based system using the APRS protocol and much of the same client software to provide fire fighting, earthquake, and weather information in much higher volume and detail than the traditional APRS system is capable of carrying.
PropNET uses the APRS protocol over AX.25 and PSK31
to study radio frequency propagation. PropNET 'probes' transmit position reports, along with information on transmitter power, elevation, and antenna gain, at various frequencies to allow monitoring stations to detect changes in propagation conditions.
Open Trac was created to provide an alternative to APRS that was cleaner and more functional than APRS.
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...
-based system for real time tactical digital communications of information of immediate value in the local area. In addition, all such data is ingested into the APRS Internet system (APRS-IS) and distributed globally for ubiquitous and immediate access. Along with messages, alerts, announcements and bulletins, the most visible aspect of APRS is its map display. Anyone may place any object or information on his or her map, and it is distributed to all maps of all users in the local RF network or monitoring the area via the Internet. Any station, radio or object that has an attached GPS is automatically tracked. Other prominent map features are weather stations, alerts and objects and other map-related amateur radio volunteer activities including Search and Rescue and signal direction finding.
APRS has been developed since the late 1980s by Bob Bruninga, callsign WB4APR, currently a senior research engineer at the United States Naval Academy
United States Naval Academy
The United States Naval Academy is a four-year coeducational federal service academy located in Annapolis, Maryland, United States...
. He
still maintains the main APRS website. The acronym "APRS" was derived from his callsign.
Network overview
APRS (Automatic Packet Reporting System) is a digital communications protocol for exchanging information between a large number of stations covering a large (local) area. As a multi-user data network, it is quite different from conventional packet radioPacket radio
Packet radio is a form of packet switching technology used to transmit digital data via radio or wireless communications links. It uses the same concepts of data transmission via Datagram that are fundamental to communications via the Internet, as opposed to the older techniques used by dedicated...
. Rather than using connected data streams where stations connect to each other and packets are acknowledged and retransmitted if lost, APRS operates entirely in an unconnected broadcast fashion, using unnumbered AX.25
AX.25
AX.25 is a data link layer protocol derived from the X.25 protocol suite and designed for use by amateur radio operators. It is used extensively on amateur packet radio networks....
frames.
APRS packets are transmitted for all other stations to hear and use. Packet repeater
Repeater
A repeater is an electronic device that receives asignal and retransmits it at a higher level and/or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances.-Description:...
s, 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. All stations within radio range of each digipeater receive the packet. At each digipeater, the packet path is changed. The packet will only be repeated through a certain number of digipeaters -or hops- depending upon the all important "PATH" setting. 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. While it would seem that using unconnected and unnumbered packets without acknowledgment and retransmission on a shared and sometimes congested channel would result in poor reliability due to a packet being lost, this is not the case due to the fact that the packets are transmitted (broadcast) to everyone, and multiplied many times over by each digipeater. This means that all digipeaters and stations in range get a copy, and then proceed to broadcast it to all other digipeaters and stations within their range. The end result is that packets are multiplied more than they are lost. Therefore, packets can sometimes be heard some distance from the originating station. Packets can be digipeated tens of kilometers or even hundreds of kilometers depending on the height and range of the digipeaters in the area.
When a packet is transmitted, it is duplicated many times as it radiates out, taking all available paths simultaneously, until the number of "hops" allowed by the path setting is consumed.
Positions/objects
APRS contains only four packet types: Position/objects, Status, Messages and Queries. The Position/object 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.The map display uses these fields to plot communication range of all participants and facilitate the ability to contact users during both routine and emergency situations. Each position/object packet can use any of several hundred different symbols. Position/objects can also contain weather information or can be any number of dozens of standardized weather symbols. Each symbol on an APRS map can display many attributes discriminated either by color or other technique. These attributes are:
- Moving or fixed
- Dead-ReckonedDead reckoningIn navigation, dead reckoning is the process of calculating one's current position by using a previously determined position, or fix, and advancing that position based upon known or estimated speeds over elapsed time, and course...
or old - Message capable or not
- Station or object
- Own object or other station object
- Emergency, priority, or special
Status/messages
The Status packet is free-field format that lets each station announce his current mission or application or contact information or any other information or data of immediate use to surrounding activities. The message packet can be used for point-to-point messages, bulletins, announcements or even email. Bulletins and Announcements are treated specially and displayed on a single "community Bulletin board". This community bulletin board is fixed size and all bulletins from all posters are sorted onto this display. The intent of this display is to be consistent and identical for all viewers so that all participants are seeing the same information at the same time. Since lines are sorted onto the display, then individual posters can edit, update, or delete individual lines of their bulletins at any time to keep the bulletin board up-to-date to all viewers.All APRS messages are delivered live in real-time to on-line recipients. Messages are not stored and forwarded, but retried until timed out. The delivery of these messages is global, since the APRS-IS distributes all packets to all other igates in the world and those that are messages will actually go back to RF via any IGate that is near the intended recipient.
A special case message can be sent to EMAIL and these messages are pulled off the real-time APRS-IS by the WU2Z Email engine and wrapped into a standard Internet Email protocol and forwarded into regular internet email.
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 weatherWeather
Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the troposphere, just below the stratosphere. Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate...
reports, short text messages, radio direction finding bearings, telemetry
Telemetry
Telemetry is a technology that allows measurements to be made at a distance, usually via radio wave transmission and reception of the information. The word is derived from Greek roots: tele = remote, and metron = measure...
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.
While the map plotting is the most visible feature of APRS, the text messaging capabilities and local information distribution capabilities combined with the robust network should not be overlooked; the New Jersey Office of Emergency Management has an extensive network of APRS stations to allow text messaging between all of the county Emergency Operating Centers in the event of the failure of conventional communications.
Technical information
In its most widely used form, APRS is transported over the AX.25AX.25
AX.25 is a data link layer protocol derived from the X.25 protocol suite and designed for use by amateur radio operators. It is used extensively on amateur packet radio networks....
protocol using 1200 bit/s Bell 202
Bell 202 modem
The Bell 202 modem was an early modem developed by Bell System. It specifies audio frequency-shift keying to encode and transfer data at a rate of 1200 bits per second, half-duplex and at a rate of 1800 bits per second full duplex using differential phase-shift keying modulation...
AFSK on frequencies
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
located within the 2 meter amateur band.
Sample APRS VHF frequencies
- 144.390 MHz - ChileChileChile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
, IndonesiaIndonesiaIndonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
, North AmericaNorth AmericaNorth America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas... - 144.575 MHz - New ZealandNew ZealandNew Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
- 144.660 MHz - JapanJapanJapan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
- 144.800 MHz - South AfricaSouth AfricaThe Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, EuropeEuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, RussiaRussiaRussia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects... - 144.930 MHz - ArgentinaArgentinaArgentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
, UruguayUruguayUruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area... - 145.175 MHz - AustraliaAustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
- 145.570 MHz - BrazilBrazilBrazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
- 145.525 MHz - ThailandThailandThailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
An extensive digital repeater, or "digipeater" network provides transport for APRS packets on these frequencies. Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
gateway stations (IGates) connect the on-air APRS network to the APRS Internet System (APRS-IS), which serves as a worldwide, high-bandwidth backbone for APRS data. Stations can tap into this stream directly, and a number of databases connected to the APRS-IS allow web-based access to the data as well as more advanced data-mining capabilities. A number of low-earth orbiting
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...
satellites, including the International Space Station
International Space Station
The International Space Station is a habitable, artificial satellite in low Earth orbit. The ISS follows the Salyut, Almaz, Cosmos, Skylab, and Mir space stations, as the 11th space station launched, not including the Genesis I and II prototypes...
, are capable of relaying APRS data.
Equipment settings
An APRS infrastructure comprises a variety of Terminal Node Controller (TNC) equipment put in place by individual Amateur Radio operators. This includes soundcards interfacing a radio to a computer, simple TNCs, and "smart" TNCs. The "smart" TNCs are capable of determining what has already happened with the packet (unit of information) and can prevent redundant packet repeating within the network.Reporting stations use a method of routing called a "path" to broadcast the information through a network. In a typical packet network, a station would use a path of known stations such as "via n8xxx,n8ary." This causes the packet to be repeated through the two stations before it stops. In APRS, generic callsigns are assigned to repeater stations to allow a more automatic operation.
Recommended path
Throughout North America (and in many other regions) the recommended path for mobiles or portable stations is now WIDE1-1,WIDE2-1. Fixed Stations (homes, etc.) should not normally use a path routing if they don't need to be digipeated outside of their local area (and most don't). Otherwise a path of WIDE2-2 or less should be used as requirements dictate. This path actually reflects the routing of packets via the radio component of APRS, and fixed stations should carefully consider their choice of path routing(s) to avoid unnecessary RF clutter outside of their local VHF listening area.Old path
Early on, the widely accepted method of configuring stations was to enable the short-range stations to repeat packets requesting a path of "RELAY" and long-range stations were configured to repeat both "RELAY" and "WIDE" packets. This was accomplished by setting the station's MYALIAS setting to RELAY or WIDE as needed. This resulted in a path of RELAY,WIDE for reporting stations. However, there was no duplicate packet checking or alias substitution. This sometimes caused beacons to "ping pong" back and forth instead of propagating outwards from the source. This caused lots of interference. With no alias substitution, you couldn't tell which digipeaters a beacon had used.New path
With the advent of the new "smart" TNC's, the stations that used to be "WIDE" are now "WIDEn-N." This means a packet with a path of WIDE2-2 would be repeated through the first station as WIDE2-2, but the path will be modified (decremented) to WIDE2-1 for the next station to repeat. The packet stops being repeated when the "-N" portion of the path reaches "-0." This new protocol has caused the old RELAY and WIDE paths to become obsolete. Digi operators are being asked to re-configure fill-in "RELAY" stations to instead respond to WIDE1-1. This results in a new, more efficient path of WIDE1-1,WIDE2-1. While most of the world has adopted the "new WIDEn-N" settings, there is an ongoing debate in the UK about the subject.Available equipment
There are a few radios on the market which include a built-in AX.25 Terminal Node Controller and APRS software, and are capable of working with or without the need for an external GPS device. Common models are the mobile Kenwood TM-D700A, its replacement, the Kenwood TM-D710A and the handheld Kenwood TH-D7A(G)and its replacement, the Kenwood TH-D72, which also has a built-in GPS receiver. Yaesu has recently entered the APRS market with their VX-8R(G) handheld and FTM-350R mobile radio.The HamHUD integrates a display for viewing the position of other stations and weather reports, and a means of sending and receiving APRS messages, and an interface for a GPS receiver. It started out in 1997 as a homebrew device, but more recently, kits have been available from time to time. It connects to a TNC which is in turn connected to a radio. The Alinco DR-135T is popular as the internally mounted T2-135 can be used with it, reducing the number of items that need to be connected together. SmartBeaconing was developed for the HamHUD by Tony Arnerich and Steve Bragg. It varies the beacon rate based on speed, and adds corner pegging. SmartBeaconing has been adopted by the TinyTrak and OpenTracker series of trackers, in a software update for the Kenwood TM-D710, and in the TH-D72 from its release.
The RTrak combined an OpenTracker 1+ and a GPS receiver along with a low power transmitter in one package. The original units produced 500 mW, but the current version puts out 350 mW.
Byonics has introduced an all-in-one device combining a GPS receiver, TinyTrak controller and synthesized 2m radio called the Micro Trak AIO which requires no assembly by the user. Other products include; TinyTrack4, Microtrak line, and tinytrack3.
ArgentData now has a 5-Watt VHF Transceiver with Integrated Tracker2 in one compact package. With a non-display GPS receiver connected, the T2-301 can be used as a tracker. With compatible display-type GPS receiver, received position reports can be output as waypoints. With a Garmin Nuvi 350 GPS receiver connected, it can send and receive APRS messages as well as display other stations as waypoints. The Nuvi 350 can be used this way with a stand-alone Tracker 2 (OT2m) or connected to a T2-135 which mounts in an Alinco DR-135 radio. The T2-301 can also be used as a stand-alone digipeater. Other products include; The New USB Tracker, and OpenTracker+.
The APRS SkyTracker is an APRS Beacon at 144.800Mhz which includes a 8W RF Transmitter, programmable PIC & u-bloc GPS receiver all on one 72x56mm PCB.
The BigRedBee GPS Transmitter is the smallest 2 meter frequency agile completely integrated APRS transmitter available. Output power is 6 watts from a supply voltage of just 7.5 volts. It also features on-board data recording that can be downloaded for later and viewing via Google Earth. A low power 70 cm version is also available.
History
Bob Bruninga implemented the earliest ancestor of APRS on an Apple IIApple II
The Apple II is an 8-bit home computer, one of the first highly successful mass-produced microcomputer products, designed primarily by Steve Wozniak, manufactured by Apple Computer and introduced in 1977...
computer in 1982. This early version was used to map high frequency
High frequency
High frequency radio frequencies are between 3 and 30 MHz. Also known as the decameter band or decameter wave as the wavelengths range from one to ten decameters . Frequencies immediately below HF are denoted Medium-frequency , and the next higher frequencies are known as Very high frequency...
Navy position reports. In 1984, Bruninga developed a more advanced version on a Commodore VIC-20
Commodore VIC-20
The VIC-20 is an 8-bit home computer which was sold by Commodore Business Machines. The VIC-20 was announced in 1980, roughly three years after Commodore's first personal computer, the PET...
for reporting the position and status of horses in a 100 miles (160.9 km) endurance run. 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
Federal Emergency Management Agency
The Federal Emergency Management Agency is an agency of the United States Department of Homeland Security, initially created by Presidential Reorganization Plan No. 1 of 1978 and implemented by two Executive Orders...
(FEMA) exercises using CETS, the system was ported to the IBM PC
IBM PC
The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981...
. During the early 1990s, CETS, now known as the Automatic Position Reporting System, continued to evolve into its current form. 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.
Related systems
The APRS protocol has been adapted and extended to support projects not directly related to its original purpose. The most notable of these are the FireNet and PropNET projects.APRS FireNet is an Internet-based system using the APRS protocol and much of the same client software to provide fire fighting, earthquake, and weather information in much higher volume and detail than the traditional APRS system is capable of carrying.
PropNET uses the APRS protocol over AX.25 and PSK31
PSK31
PSK31 or "Phase Shift Keying, 31 Baud" is a digital radio modulation mode, used primarily in the amateur radio field to conduct real-time keyboard-to-keyboard informal text chat between amateur radio operators.- History :...
to study radio frequency propagation. PropNET 'probes' transmit position reports, along with information on transmitter power, elevation, and antenna gain, at various frequencies to allow monitoring stations to detect changes in propagation conditions.
Open Trac was created to provide an alternative to APRS that was cleaner and more functional than APRS.
See also
- List of APRS nodes
- Automatic Identification SystemAutomatic Identification SystemThe Automatic Identification System is an automatic tracking system used on ships and by Vessel traffic services for identifying and locating vessels by electronically exchanging data with other nearby ships and AIS Base stations...
- Position reporting system used for marine traffic - TCAS
- Spartan Packet Radio ExperimentSpartan Packet Radio ExperimentThe Spartan Packet Radio Experiment was an Amateur Radio communications experiment that flew on the Space Shuttle Endeavor's STS-72 mission as part of NASA's Spartan/OAST-Flyer spacecraft in January 1996...
- An experiment intended to test the tracking of satellites via amateur packet radio, flown on Space ShuttleSpace ShuttleThe Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
mission STS-72STS-72STS-72 was a Space Shuttle Endeavour mission to capture and return to Earth a Japanese microgravity research spacecraft known as Space Flyer Unit...
.
External links
- HF-APRS. Net14 The World Wide APRS Net on HF-bands.
- Live APRS. See APRS in action with a live video stream from a UK trucker.
- APRS website. The original APRS page with all addendums and updates.
- APRS Florida West Central Florida info and the APRSfl.net Tier2 APRS-IS Server
- Queensland, Australia APRS Information
- APRS Wiki Site More specific APRS setup information
- APRSISCE/32 for Windows Mobile and Win32 Full-Featured APRS (RF and -IS) client
- APRS for Windows Mobile Using OpenStreetMaps with PocketPC PDAs
- APRS on PocketPC PDA options Using APRS with PocketPC PDAs
- www.findu.com Web-based access to worldwide APRS real-time data
- aprs.fi Automatically updating real-time APRS view using Google Earth and Google Maps, available in 14 languages
- OpenAPRS Web-based APRS real-time data using Google Earth Maps
- oAPRS Web-based APRS Packet Search Engine for station, weather, telemetry and position lookup and debugging.
- DB0ANF Web-based Access to APRS Station and Network Data
- HamHUD A message capable APRS "heads up display" with LCD. SmartBeaconing was first developed for the HamHUD.
- APRS Server List Publicly available servers hosting the APRS-IS
- APRS World Open Source web-based APRS database
- APRS Specification Official APRS specification document
- KCAPRS Organization Getting started in APRS
- PropNET Homepage If the band is open and no one is active, does anybody hear it?
- Northwest APRS Homepage Pacific Northwest APRS alternate Wiki
- APRS in Australia Australian (VK) APRS National Information Site
- APRS Argentina Group Argentinian APRS Group (Spanish)
- APRS in Brazil Brazilian APRS Network since 1998 (Portuguese)
- Peet Bros. Company, Inc. Homepage Weather Station Hardware with direct support for APRS / TNC Interface
- Official UI-View Site Roger Barker G4IDE SK was the author of UI-View
- UI-View M0CYP UI-View Web Resource, including registration
- Radioactive Networks GPS projects
- Xastir A popular Open Source APRS client for Linux, Windows, Mac OS X and more.
- APRS ON4SAX A free online visual tracker for APRS
- USAPhotoMaps A free Windows program
- aprs.qrz.ru APRS in Russia
- APRS.cz APRS in Czech
- JAPRSX APRS Information in Japanese
- http://zl2tze.ath.cx/aprs APRS Network Analysis New Zealand
- http://zl2tze.ath.cx/ui-view Ui-View Webserver New Zealand
- http://zl2tze.ath.cx/aprs2/index.htm General APRS information
- http://zlhams.wikidot.com ZLhams Wiki