What is APRS?

APRS is a system for transmitting messages and geographical GPS coordinates based on Packet (AX.25 Protocol) and AFSK 1200 modulation. APRS is designed to work in a small territory of one region, in the field of one digital relay (DIGI) or a group of relans connected to the network.

Another application of APRS is automatic weather stations that communicate the temperature, pressure, and wind speed through the air. They can be seen on APRS card. There are fixed and mobile beacons. Lighthouses that change their location along with the radio amateur and transmit the coordinates on the air are called "trackers" from the English word "tracking" - "отслеживание". Путь ("трек") будет нарисован на сайте, который собирает данные APRS. Либо, по координатам GPS других станций, передаваемых в эфир на частоте APRS 144.800 МГц можно в программе APRSdrOID Find other amateur radio amateurs nearby.

Using APRS, you can transmit messages on a certain territory without using the Internet. That is, all APRS stations listen and transmit on one frequency of the VHF range. Traditionally, the eastern hemisphere in the two -meter range uses the frequency of 144.800 MHz, but in America the frequency of 144.625 MHz. FM modulation, transmission method - Packet 1200 BPS. In the range of 70 centimeters, the frequency of 432.500 MHz is used.

APRS is called a global network - a package from the air passes through a gateway and is on the site https: //aprS.Fi или [https://aprs2.radiorubka.org]https://aprs2.radiorubka.org/). Таким образом, другие радиолюбители могут наблюдать активность APRS станций с помощью веб-браузера. Можно настроить программу APRSDROID или APRSIS32 или UIVIEW32 для отправки пакетов APRS по сети Интернет TCP-IP, без использования эфира. Для работы по TCP-IP понадобится получить пароль (только лицензированные радиолюбители могут использовать APRS) - для подключения к APRSdrroid по TCP-IP нужно получить passcode. Он выдаётся team AT aprsdroid.orG within a few days or a couple of weeks after providing an electronic copy of its amateur license.

What is Packet radio?

ПакThis radio is the transmission of messages and data in the form of packages, according to the AX.25 protocol. The history of Packet originates in the 70s of the last century. Then, long before the Internet, package radio was used to organize electronic ads (BBS) with access on the radio. Then, a weather station appeared, where packages can consist not only of the text, but also of the bit fields, for example, temperature values, wind speed. Package radio - not for competitions in radio sports, and not a field of weak signals. Using a package radio, radio communications (QSO) with neighbors in the region can be carried out. Previously, everything that is required for this is a computer with a TNC controller on both sides and VHF of a 2 -meter range (144 MHz), with the possibility of connecting a linear entrance and sound output to them.

What is AFSK 1200 modulation?

Modulation, along with the radio station, is the lowest, physical level for transmitting messages.
Two tones 1200hz and 2200HZ are used to transmit AFSK, which change during information transmission.

• Type of modulation - FSK
• speed 1200 BOD (BPS)
• Used 2 tones 1.2 kHz for "Mark" и 2,2 кГц для "SpaCE "
• The frequency shift between tones is 1 kHz.
• Due to rapid manipulation, it looks like a spectrum of about 1300-1400 kHz wide.
• At the beginning of the program there is a preamble of short flags serving for synchronization of modems, with a period of 6.7 ms.
• The volume level of both tones should be the same (the sound spectrum of the AFSK signal should be even).
• AFSK 1200 package modulation is widely used by amateur radio amateurs in the range of 2 meters (144-146 MHz) to transmit APRS at a frequency of 144.800 MHz in Europe and Asia and 144.390 MHz in America, 145.175 MHz in Australia.

What other types of modulations for APRS exist?

• FSK modulation at a speed of 300 BOD (used on short waves in the ranges of 30 and 20 meters).
  Two tones mark и SpaCE is separated by the interval of 200 Hz. For transmission of radio data, it works in SSB mode.
• BPSK modulation-used on amateur satellites DO-64 (Delfi-C3), AO-73 (Funcube-1). Speeds 300, 600, 1200, 2400 baud.
• G3RUH FSK is used on VHF when transmitting at a speed of 9600 BOD. Coding is used using polynoma and limiting the spectrum width. Application: Cubesat radio amateur satellites.
• 9600 BPS GMSK - used on satellite FalconSaT-3 for APRS.

What is AX.25

AX.25 - one of the transmission protocols (such as Inet TCP -IP V4, IPV6, IPX, AppleTalk). The difference between AX.25 and others is used mainly by radio amateurs, on nodes working in Packet mode. Also, through AX.25, they can exchange application information both on one personal computer and on different ones. The AX.25 protocol operates at the logical and software level (above physical). The transfer of information between programs with AX.25 support is organized using sockets (file flows). Access "one to many." Inside the sockets, low -level ("raw") data packages are transmitted consisting of 0 and 1. Frames are used to check the integrity of data packages in AX.25, which are organized according to the HDLC standard. There are two types of stations - the end stations Node and the intermediate nodes (relay) that communicate with each other - one transmitter and one or many receivers. There is an opportunity for traffic routing - with intermediate nodes (relayers) and limiting the number of intermediate components for each message. The end nodes are called terminal - TNC TErminal node controller. Промежуточные узлы бывают репитерами (digipeater или, сокращённо, digi) или же шлюзами в Интернет - "гейтами" (от слова gaTE - gateway). Through gateways, traffic traffic is entered into the APRS network (from the air to the computer network) or goes out (broadcasts on air). Through AX.25 you can transmit any data, even TCP-IP packages. Due to the low speed of the radio interfaces (1200 BOD), AX.25 radio amateurs use short messages 7 bits (only the letters of the Latin alphabet and numbers) or bit fields (telemetry, weather). All end nodes transmit data through one channel (at the same frequency). All APRS stations have the same rights to use the transmission channel. In order to avoid gear linings from different stations ("Collisies"), APRS implemented the employment of the radio channel with the TNC rye before the transmission starts.

What is HDLC

HDLC Protocol of control of the integrity of the frames AX.25 and synchronization of the receiver and transmitter. Zero (0) is encoded by a change in the state of modulation from negative to positive, and when transferring unit (1), the state of modulation does not change. The beginning and end of the frame is marked with synchro-sequence of 01111110 (or 0x7E). Long gears 1 are prohibited (before each unit walking, symbol 0 is inserted by units). At the end of the message, a 16 -bit control amount is added. A feature of the protocol is its insensitivity to a change in the polarity of the signal. That is, inverting the amplitude of the modulating signal C + on - and vice versa does not cause transmission problems.

What is kiss

KISS is a special protocol for the interaction of a computer and TNC. Since there is a sequential port between the computer and TNC, the data from the computer are packaged in HDLC frames and are transmitted between two points - the computer and TNC.
Both of these devices should understand this protocol. Programs for digital radio amateur species FLDIGI or MIXW can act as KISS controllers. However, for KISS, either hardware TNC controllers or TNC controllers program emulators are used. According to the KISS protocol, it is transmitted as data so commands for managing TNC. The KISS protocol was invented that various programs and controllers can communicate "in the same language."

TNC models

For example, popular and hardware controllers kantrOnics for amateur radio, MFJ -1270B or KISS software controller, which emulates a hardware controller in PC memory - serves to connect programs to it.

List of TNC controllers, which are implemented in the hardware:

• AEA PK-88 TErminal Node Controller
• KantrOnics KPC-3
• KantrOnics KPC-3 Plus
• KantrOnics KPC-9612
• KantrOnics Kam-98
• KantrOntics Kam-Plus
• KantrOnics Kam-XL
• MFJ-1270CX (model is discontinued)
• MFJ-1270CTX (Model is discontinued)
• MFJ-1270B
• MFJ-1270X
• MFJ-1275
• Bux communications Corp (BUX CommCo ™) RASCAL™ ("Radio And Sound Card Adapter Link" ™)
• Rigblaster StandarD.
• Rigblaster Plus (фирмы West Mountain Radio)
• Rigblaster AdvantaGE
• Rigblaster Plug and Play
• TIGErtronics SignaLink USB
• TIGErtronics SignaLink SL-1 Plus
• Timewave HamLink USB
• TimewaVE PK-96
• Timewave PK-232/DSP
• Built-in TNC controller of the Kenwood TS-2000 Transiver.
• Kenwood Transivers TM-D710, TM-D710A, TM-D710E, TM-D710GA models.
• Controllers built-in in the radio station D-STar.
• Byonics - TinyTrak4
• Kiss TNC based on Arduino (here)
• Homemade TNC Controller IZ1DNJ

List of TNC software controllers and sound program modems Packet/AFSK:

• Uz7ho soundmodem - see site Uz7ho packet raDio (Windows)
• AGWPE SOUNDmodem - AGW Packet Engine (Windows)
• Thomas Sailer, HB9JNX/AE4WA "soundmodem" (Linux: Ubuntu и DebiaN, Mint, etc.)
• WB2OSZ DireWolf (Linux и Raspberry pi)
• Mixw http: // goryham.qrz.ru/digi/mixw/packet.htm
• Fldigi https://github.com/la5nta/fldigiattaCh

What is Mic-E?

Mic -E is a regime uniting voice and digital communication (E - from the word Echolink) - transmitting APRS packages through voice repiteters. The APRS package is transmitted every time after each press and when the tangent button is released or the timer. This mode implemented in some radio stations. For a more reliable transmission, the length of the package is reduced to 0.3 seconds, only data are transmitted in digital compressed form: position, type of vehicle, speed, course (direction of movement). Mic-e message is short, only 30 bytes, while the usual APRS message consists of 90 bytes.

In order for MIC-E to work, the retransplant must recognize Mic-E Messages, it must be able to process such packages. So that other users do not hear the noise, there is protection against short tangent on the relayers, and the bags are shorter than 0.3 seconds and do not pass through the retransplant, do not cause opening the nozzle. However, messages at the frequency of Mic-E Retranstaller go to the APRS network. With the appropriate tuning of the repiter. ;-)

Mic-E support Kenwood, Anytone and Yaesu radio stations. A full list of radio support for Mic-E:

• Yaesu ftm-350
• Yaesu vx-8g
• Kenwood D72
• Kenwood Th-D7A, D7E
• Yaesu ftm-400dr
• Yaesu ft1d
• Kenwood Th-D74
• Anytone D878uv
• Anytone D578UV
• Yaesu ft-1d (r)
• Yaesu ft-2d (r)
• Yaesu ft-3d (r)

The first version of Mic-E was implemented in the form of a separate “box” (produced by TAPR/PACCOMM) which was connected to the microphone and dynamics of the radio station with wires.

The call sign to the APRS

The call sign for the sender and the recipient consists of a maximum of 6 signs. Example: RS0iss, UB3ZZZZ - coincides with the radio amateur call sign.

The call sign of the recipient in APRS

It can be a real radio amateur call sign (6 signs) or a standard recipient provided for in the APRS system:

Air, ALL, AP, Beaconcq, GPS, DF, DGPS, Drill, DX, ID, Java, Mail, Mice, Qst, Qth, RTCM, Sky, Space, Spc, Sym, Tel, Test, TLM, WX, ZIP.

For example, the GPS recipient is used by trackers who send the station coordinates to the Internet, Tel and TLM for telemetry.

What is SSID

The digital value in the field of the source address (i.e., the sender) standing after the suffix of the call sign through the hyphen is called the SSID field.
Example: UA1AA-7, -7 This is SSID. The SSID field determines the type of station and the icon on the map (if another is not indicated in the icon field).
SSID is used to separate several APRS stations belonging to one call sign. For example, RV1VV House, RV1VV-2 DACHA, RV1VV-5 smartphone, RV1VV-13 meteorway.

Examples of standard SSID:

Basic APRS symbols

What is the path of Unproto and WIDE value?

The Unproto path contains instructions on repetition of packages and acts only on digital retranstas.

According to the old standard, to transfer packages through the node, the TNC final device should have indicated the word Relay in the Path field. The word Relay means that such a package should be relayed by a digi-refiter on the air. Since there are more reptitors, Digi relayers also began to unite in chains and stars to increase the coating. In this regard, Widen-N paths began to be used. This is done to prevent endless relaying of packages and restricting the coating with one package of the territory - with each retransation, the number indicated in the SSID (for example, -7) N decreases by 1 and in the end the package will cease to be processed by relans.

ЗнаClassing the Unproto path for one relay: Wide1-1.

Although you can introduce a call sign with an asterisk at the end (like Ra1aaa *) in the Unproto, but practice shows, this does not make sense, because The path in APRSDROID report is hidden, Ecoan is displayed all packages from any stations in direct visibility, and not just “directed” using the Unproto path.

See article on APRS.Fi "HOW APRS Paths work"

Using the empty path of Unproto in APRS

A package that does not indicate the WIDE path will not be relayed by any repeater, but it can still be listened directly. It can intercept the igate and transfer it to APRS-Sis via the Internet.
The package without a path is similar to an unpertured, general challenge (without indicating the call sign). For example, RX1xx transmission:

2) to unsubscribe

Example:

Related publications

APRS via satellites and KV (theory and practice)

Autonomous Trackers and Digi for the APRS system

APRS Cables for Baofeng UV-5R: Two options

`Using Direwolf with Xastir instead of SoundModem'

Experience in using APRSDroid с радиостанцией BaOFENG