Automatic
Position Reporting System
APRS is an amateur
radio based digital communications system for local, tactical,
real-time exchange of information among all members of a net,
including map based displays for situational awareness. It was
developed by Bob Bruninga,
WB4APR∞,
who currently works at the United States Naval Academy.
Capabilities
APRS is used to
transmit real-time information such as messages, bulletins,
announcements and the locations of any stations or objects via
amateur packet radio protocols. Real-time reporting of station
position for mobiles is facilitated using the Global Positioning
System. APRS is capable of transmitting a wide variety of data
including weather reports, short text messages, radio direction
finding bearings, telemetry data, and storm forecasts. These
reports can be combined with a computer and mapping software to
show the transmitted data superimposed on a variety of map
displays.
Technical Information
In its most widely used form APRS is transported over the air
using the AX.25 protocol at 1200 baud Bell 202 audio
frequency-shift keying on frequencies located in the amateur
2-meter band . An extensive digital repeater, or digipeater
network provides transport for APRS packets on these
frequencies. Internet gateway stations (i-Gates) 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. 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 and the International Space Station are
capable of relaying APRS data.
History
Bob Bruninga implemented the earliest ancestor of APRS on an
Apple II 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-mile
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 FEMA
exercises using CETS, the system was ported to the IBM PC.
During the early 1990s, CETS, now known as the Automatic Packet
Reporting System, continued to evolve into its current form. As
GPS technology became more widely available, 'Packet' was
replaced with 'Position' to better describe the most common use
of the system. |
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APRS Frequencies
Primary VHF Networks
North America: 144.39 MHz (Voice Alert 100.0 Hz CTCSS, mobiles
only please!)
Europe: 144.80 MHz
Australia: 145.175 MHz (Voice Alert 123.0 Hz CTCSS)
New Zealand: 144.575 MHz
Argentina: 144.930 MHz
Japan: 144.640 MHz
Alternative Input VHF Networks
For low-powered trackers only:
Many areas: 144.99 MHz
Western Washington State: 144.35 MHz
UHF Networks
Australia (VK): 439.100 MHz 1200 baud (in selected areas)
Puget Sound, WA: 440.875 MHz 1200/9600 baud
Kansas / Missouri: 446.175 MHz 1200 baud (primary, with
infrastructure)
Kansas / Missouri: 441.175 MHz 1200 baud (secondary / special
event, no infrastructure)
HF Frequencies
Dial frequencies based on default tones used in popular packet
devices.
30 meters, 300 baud packet, Worldwide
|
USB Dial Frequency |
Mark Frequency |
LSB Dial Frequency |
| KAM, MFJ, TinyTrak |
10.147.600 MHz |
10.149.200 MHz |
10.151.000 MHz |
| AEA |
10.147.100 MHz |
10.149.200 MHz |
10.151.500 MHz |
Satellites
| Satellite |
Uplink
Frequency |
Downlink
Frequency |
Alias |
Mode |
Status |
| ISS |
145.990 MHz |
145.800 MHz |
ARISS |
1200 baud AFSK
packet |
Active |
| PCSAT-2 |
145.825 MHz |
435.275 MHz |
ARISS or
WIDE2-2 |
1200 baud AFSK
packet |
Active |
| PCSAT-1
(NO-44) |
145.825 MHz |
145.825 MHz |
ARISS |
1200 baud AFSK
packet |
Daylight Ops
Only! |
| AO-51 (Echo) |
145.860 MHz |
435.150 MHz |
PACB-1 |
9600 baud FSK
packet |
Active (see
schedule) |
Satellites are subject to doppler shift and you should adjust
your uplink/downlink accordingly. Doppler will make the
frequency on a LEO shift as follows:
2 meters - +/- 3kHz
(FM capture effect negates the need to adjust on this band)
70 cm - +/- 10kHz
Here is the location of the WR4RC-3 Digipeater. Click
here for a map of all local stations near WR4RC-3.
Click here to find the Mobile APRS station
 N4ZZQ-12.
This is Al Keen's Jeep with an onboard tracker.
Check out Google APRS. Its Live internet APRS
data streamed to a Google map. Click and Zoom anywhere.
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