aprs
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WHAT IS THE APRS
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The APRS system was invented and introduced by Bob
Bruninga, an amateur radio operator (WB4APR). Officially,
APRS is the abbreviation Automatic Position Reporting
System.
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The APRS system was invented and introduced by Bob Bruninga, an amateur radio
operator (WB4APR).
WB4APR USA
Robert.E.Bruninga
115Old.FarmCt
Glen.Burnie.MD21060
USA.
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Bob Bruninga History (WB4APR).
1960s Playing with radio, xtal sets, Tubed CB sets and converted car radios
1963 Novice: WN4APR with ARC-5 Command sets on 40/80m
1973 Playing with VHF FM in Japan and building radios
1975 Wrote first RTTY BBS, later added phone, then RF ASCII
1978 Worked with AMRAD group developing AX.25 in USA
1982 wrote first data map program plotting navy ship positions on APPLE2 in
Japan.
1983 wrote VIC-20 VHF/HF BBS and Gateway and defined 200 Hz shift due
to development of mods to dozens of surplus VADCG bell 103 modems with
cross-county links to W0RPK, W9TD, and K7PYK on 10.149 MHz Remained
on the air 5 years through 1989 under the FCC STA for automatic packet HF
operations. Developed larger system on the Commodore C-64 for BBS's used
around the world through the 90's.
1984 Developed CETS (Connectionless Emergency Traffic System) on Vic-20
and C-64 for digital packet commas in support of 100 mile cross country
endurance run for AMRAD.
1986 or so, used CETS for amateur packet radio support of the FEMA National
Disaster Medical System exercises in DC area.
1988 or so, ported CETS over to the new IBM AT PC and began to add maps
and position plotting of stations.
1990 or so. Began hand making maps of the USA for CETWS use.
1992 Changed name of CETS to APRS and presented paper at DCC in Teaneck NJ
where I first met Sproul Brothers who later wrote Mac and WinAPRS.
1994 Developed MIM Module with N3MIM and Mic-E protocol. Proposed WIDEn-N
digipeating
1996 or so worked with TAPR to produce Mic-Encoder and Paccomm to indroduce
callsign-substitution RELAY, WIDE, TRACE digipeating
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1998 Worked with Kantronics to introduced WIDEn-N digipeating and Kenwood to
introduce the TH-D7 APRS warlike Talkie
2000 Kenwood introduced the D700 APRS mobile radio
2001 Introduced APRS touch-tone, APRS reporting of IRLP and Echolink. Developed
PCSAT-1.
2004 Began the New-N Paradigm to rid APRS of all old legacy digipeating algorithms
and focuse on user education for one standard
2005 Began initiative to include operating Frequency in all packets.
2006 Developed PCSAT-2 to fly on outside of ISS
2007 Developed ANDE, RAFT and MARScom amateur satellites for deployment
by Space Shuttle
2008 Yaesu introduced the VX-8R APRS walkie-Talkie.
2008 Introduced the Universal Ham Radio Text Messaging Initiative to tie together the
two-dozen or more existing amateur radio text messaging capabilities.
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Officially, APRS is the abbreviation for Automatic Position Reporting System.
Some feel APRS should be the abbreviation for Automatic Packet Reporting System.
Originally the system only reported positional information. However, in recent years, APRS
has become more than a standard for reporting the simple location of an object. It is now
used for
APRS Features
Station Status Station Positions Messages
Bulletins Stations Heard
Station Tracking APRS Satellites DX Clusters
Internet and Igates Frequency Coordination
Protocol Reporting weather
Digital Advance Fox Hunting E.g. It like
Internet Access
Locations of objects that have no actual APRS systems aboard, like starting locations for
races, check points for those races, etc.
Basically, an APRS system requires a location sensor (GPS, but sometimes just a person
with a map), a Packet radio transmission system on one end and a packet radio receiver and
a computer on the other end of the system.
The first system collects its current location and encodes it in a standardized format as a
string of text and transmits that information as a beacon. The transmission is NOT directed at any one station but rather beaconed out for all listening stations to hear and interpret.
A second system receives the information using APRS software and then decodes the packet and, typically, places an icon on a map showing the transmitting station's location.
This page is only meant to provide this snapshot overview of APRS. Visit the links below to
get more detailed information on this technology.
APRS is a real-time tactical 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 radio.
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APRS is different from regular packet in four ways. First by the integration of maps and other data displays to organize and display data, second, by using a one-to-many protocol to update everyone in real time, third, by using generic digipeating so that prior knowledge of the network is not required, AND FORTH, since 1997, a worldwide transparent internet backbone, linking everyone worldwide. APRS turns packet radio into a real-time tactical communications and display system for emergencies and public service applications (and global communications). Normal packet radio has only shown usefulness in passing bulk message traffic (Email) from point to point. It has been difficult to apply conventional packet to real time events where information has a very short life time and needs to get to everyone
Although the recent interfaces to the Internet make APRS a global communications system for live real-time traffic, this is not the primary objective. But like all of our other radios, how we use APRS in an emergency of special event is what drives the design of the APRS protocol. Although APRS is used 99% of the time over great distances, and benign conditions, the protocol is designed to be optimized for short distance real-time crisis operations.
APRS is a full featured automatic vehicle location and status reporting system too. It can be used over any 2-way radio system including HAM, CB, Marine Band, and Cellular Phone. Sat. Aeronautical
APRS Tracking Example
What's a Tracker?
A tracker is the means by which a mobile station can be tracked. It may consist of a radio,
antenna, TNC and GPS but since most of the time the mobile just transmits unconnected UI frames, the
receiver part of the TNC is redundant. Therefore more and more stations are using small-dedicated
tracker units instead of full-featured TNCs. These trackers can have various operating abilities. The
simplest will just transmit a UI packet indicating their position every few minutes, others have more
functions
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Digipeaters
NMEA Data APRS recognizes raw ASCII data strings conforming to the NMEA 0183
Version 2.0 specification, originating from navigation equipment such as
GPS and LORAN receivers. It is recommended that APRS stations interpret
at least the following NMEA Received Sentence types:
GGA Global Positioning System Fix Data
GLL Geographic Position, Latitude/Longitude Data
RMC Recommended Minimum Specific GPS/Transit Data
VTG Velocity and Track Data
WPT Way Point Location
Packet Timing
Since APRS packets are error-free, but are not guaranteed delivery, APRS
transmits information redundantly. To assure rapid delivery of new or
changing data, and to preserve channel capacity by reducing interference
from old data, APRS should transmit new information more frequently than
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old information.
There are several algorithms in use to achieve this: •
Decay Algorithm
Transmit a new packet once and n seconds later.
Double the value of n for each new transmission. When n reaches the net
cycle time, continue at that rate. Other factors besides “doubling” may be
appropriate, such as for new message lines.
• Fixed Rate
Transmit a new packet once and n seconds later. Transmit
it x times and stop.
• Message-on-Heard Transmit a new packet according to either
algorithm above. If the packet is still valid, and has not been
acknowledged, and the net cycle time has been reached, then the
recipient is probably not available. However, if a packet is then
subsequently heard from the recipient, try once again to transmit the
packet.
• Time-Out
This term is used to describe a time period beyond which it
is reasonable to assume that a station no longer exists or is off the air if
no packets have been heard from it. A period of 2 hours is suggested as
the nominal default timeout. This time-out is not used in any transmitting
algorithms, but is useful in some programs to decide when to cease
displaying stations as “active”. Note that on HF, signals come and go, so
decisions about activity may need to be more flexible
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Technical information
In its most widely used form, APRS is transported over the AX.25 protocol using 1200 bit/s Bell
202 AFSK on frequencies located within the 2 meter amateur band.
Sample APRS VHF frequencies
144.390 MHz – Chile, Indonesia, North America
144.575 MHz – New Zealand [3]
[4]
144.660 MHz – Japan
144.800 MHz – South Africa, Europe, Russia
144.930 MHz – Argentina, Uruguay
145.175 MHz – Australia
145.570 MHz – Brazil
145.525 MHz – Thailand