Automatic Packet Reporting System
The Automatic Packet Reporting System ( APRS ) is a special form of packet radio in the amateur radio service . The system was developed in the 1980s by the American radio amateur Bob Bruninga ( callsign WB4APR).
description
APRS enables the automated distribution of data (e.g. GPS position, weather data , short text messages) over any distance in the packet radio network. This data is transmitted on uniform simplex frequencies in the 2-meter band at a bit rate of 1200 bit / s and in some cases also 70-centimeter band (there also with a bit rate of 9600 bit / s) and in the 11-meter band ( CB) transferred.
In order to load the packet radio network as little as possible, but to be able to distribute the data as globally as possible, the individual data packets are only routed wirelessly by the packet radio digipeaters until they are sent to a special APRS digipeater (sometimes also "IGATE" - as short for "Internet Gateway " - called). This is a packet radio digipeater that is connected to the Internet. The data fed into the Internet can be accessed via a web browser , with APRS software that supports IGATE, or via packet radio. In addition to terrestrial digipeaters, amateur radio satellites are also available as APRS digipeaters.
APRS is now very popular among radio amateurs and is also becoming more and more established in the 11-meter band in order to be able to communicate one's own position to one another in mobile operation. APRS has also proven to be helpful in the case of car theft, as these systems are usually permanently installed in the vehicles. APRS weather stations are z. B. very helpful during storms to follow the weather via packet radio and the Internet.
A symbol can be assigned to each call sign, and there is also the option of sending a short status text. The system also supports short messages.
Emergency calls can be sent in connection with the current (GPS) position. There is a special "Emergency" symbol and a corresponding status text for this purpose. Such a packet triggers an alarm at the receiving stations: The APRS-capable handheld radios from Kenwood trigger an acoustic alarm and expect manual confirmation; Computers with a map display also zoom in on the location. Since the APRS packets are forwarded via digipeaters and through the Internet, a simple alarm can draw attention to thousands of stations around the world.
During emergency radio exercises via amateur radio satellites "Satellite Simulated Emergency Test - SSET" a. APRS is used to send e-mails via satellite and to confirm receipt.
For APRS operation you need (in addition to a license to participate in the amateur radio service ):
- a data source (usually a GPS receiver; e.g. serial GPS mouse)
- an APRS module
- an amateur radio transceiver for the 2 meter band or Internet connection
- optionally an amateur radio transceiver and a Terminal Node Controller (TNC) for access to packet radio.
For CB -APRS operation you only need:
- a data source (usually a GPS receiver; e.g. serial GPS mouse)
- an APRS module
- a CB radio transceiver for the 11 meter band or Internet connection
- optionally a CB transceiver and a TNC for access to packet radio.
There is also APRS operation on shortwave . Two standards have established themselves here: On the one hand, 300 baud AX.25 and, on the other hand, the proprietary Robust Packet Radio (RPR).
The APRS operation via space stations and amateur radio satellites with digipeaters is also carried out. The international space station , the amateur radio satellite OSCAR 44 and various CubeSats with an amateur radio payload are currently available for this purpose .
Voice alert
This concept provides that stations indicate readiness for voice connections by sending out a CTCSS sub-tone - 123 Hz in Germany , 136.5 Hz according to other sources in Europe. When the tone squelch is activated, you can only hear beacons from stations that send out this sub-tone and you can address them briefly - meaningfully by using the signal word "Voice Alert" so that the called station can clearly assign the call. After changing the frequency you can have a normal radio conversation.
Unmanned automatic stations are not allowed to send out this sub-tone, as otherwise the principle of Voice Alert (quasi automatic CQ calling) would no longer work.
In Kenwood radios with integrated APRS-TNC such as the TH-D72 or the TM-D710 , only the sound output is interrupted when the voice alert function is activated, but not the data evaluation. In dual operation, the sound output in the APRS band can be largely or (almost) completely prevented by activating the receiving-side voice alert function and the other band can be prevented from being disturbed (possibly with small reception interruptions during APRS transmission) use in Phonie.
If you use this concept with other transceivers, you have to ensure that the APRS received data can be evaluated in spite of the activated sub-tone squelch, since otherwise, for example, the carrier detection will no longer work and beacons will be transmitted despite the frequency being used. In the simplest case, when the tone squelch is activated, only the sound output on the loudspeaker is interrupted and the received audio is still output on the packet radio connection of the transceiver used for APRS. Otherwise, with some duoband receivers, there is still the option of setting PR reception to one of the two receiving parts, setting its volume to zero and the second receiving part with activated tone squelch only for listening to voice alert stations or also to use for sending with sub-tone.
APRSLink
The global WinLink 2000 network for asynchronous communication via amateur bands can also be used via APRS using APRSLink. This means that it is possible to send and receive e-mails via an APRS message. These are transmitted to a Central Message Server ( CMS ) via an IGATE .
Frequencies
| 30 meter tape | Operating mode | region |
|---|---|---|
| 10.1476 MHz | 300 baud USB | Worldwide |
| 20 meter tape | Operating mode | region |
| 14.103 MHz | LSB with 300 baud | Worldwide |
| 11 meter tape | Operating mode | region |
| 27.235 MHz | FM with 1200 baud AFSK | Worldwide |
| 10 meter tape | Operating mode | region |
| 29.250 MHz | FM with 1200 baud AFSK | Worldwide |
| 2 meter tape | Operating mode | region |
| 144.390 MHz | FM with 1200 baud AFSK | United States |
| 144.640 MHz | FM with 1200 baud AFSK | Japan |
| 144.800 MHz | FM with 1200 baud AFSK | standard frequency common in Europe |
| 145.175 MHz | FM with 1200 baud AFSK | Australia |
| 145.525 MHz | FM with 1200 baud AFSK | Thailand |
| 145.825 MHz | FM with 1200 baud AFSK | International space station uplink / downlink |
| 145.825 MHz | FM with 1200 baud AFSK | OSCAR 44 downlink |
| 145.828 MHz | FM with 1200 baud AFSK | OSCAR 44 uplink |
| 70 centimeter tape | Operating mode | region |
| 432.500 MHz | FM with 1200 baud AFSK | Germany , Luxembourg , Lorraine , tests in Vienna |
| 433.800 MHz | FM with 1200 baud AFSK | Test operation since September 2012 in the Innviertel |
| 430.5125 MHz | FM with 1200 baud AFSK | Test run in Holland |
| 433.775 MHz | LoRa at 128 kbps | Test operation in OE and DL |
Web links
- APRS main page
- CBAPRS main page
- APRS Frankfurt - APRS in the Rhine-Main area with many tips from practice for practice
- aprs.fi: Fast live map display of APRS data
- Comprehensive introduction to APRS (possibilities, technology, software, ...)
- DIY APRS tracker from DH3WR
- Information on APRS in Austria ÖVSV Wiki
- Stations digipeated via the International Space Station
- 44 digipeated stations via OSCAR
Individual evidence
- ↑ APRS via SAT / ISS. Retrieved December 21, 2012 .
- ↑ AMSAT Live OSCAR Satellite Status Page. Accessed February 12, 2017 .
- ↑ APRS detailed knowledge - Voice Alert: . APRS in Germany. Retrieved February 13, 2011.
- ↑ APRS Voice Alert: . ARPS page by Bob Bruninga, WB4APR. Retrieved February 13, 2011.
- ↑ Voice Alert: . APRSWiki Community Portal. Retrieved February 13, 2011.
- ↑ Voice Alert (PDF; 250 kB). Adam Chorościan SQ3XZ. Retrieved February 12, 2017.
- ↑ APRSLink. Retrieved December 21, 2012 .
- ↑ APRS on 70cm . Wiki of the Austrian Association of Experimental Broadcasters (ÖVSV)