APRS dan eQSO

APRS


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 instant access. In addition to messages, alerts, announcements and bulletins, the most visible aspect of APRS is it’s map display. Anyone may place any object or information on their 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 was developed since the late 80’s by Bob Bruninga, callsign WB4APR, currently a senior research engineer at the United States Naval Academy. The acronym “APRS” was derived from his callsign. In the 1990’s as GPS excitement dominated many new applications, the “P” was often referred to as “Position” instead of the original “Packet”. But this so skewed the public perception of APRS as only a GPS and Weather Position tracking system, that recently, the emphasis has returned to the broader “Packet” applications.

  • Positions/Objects

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. APRS contains only four packet types, Position/objects, Status, Messages and Queries. The Position/object packets contain not only the latitude/longitude, course and speed, but also fields for power, antenna height and gain and voice operating frequency. The map display uses these fields to plot communication range and connectivity of all participants ane facilitate the ability to contact users during both routine and emergency situations. Position/objects can also contain Weather information or can be any number of dozens of standardized weathere symbols. Each position/object packet can use any of several hundred different symbols.

Each symbol on an APRS map can display many attributes disriminated either by color or other technique. These attributes are:

Moving or Fixed
Dead-Reckoned or Old
Message Capable or not
Station or object
Own object or other station object
Emergency, Priority, orspecial

  • 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, bulletings, 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 weather 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.

  • Technical Information

In its most widely used form, APRS is transported over the AX.25 protocol using 1200 baud Bell 202 audio frequency-shift keying(AFSK) on frequencies located within the amateur 2-meter band:

* North America: 144.390 MHz with 144.990 occasionally used as an alternate input frequency for local low power stations
* Australia: 145.175 MHz with 144.390 MHz available for as a secondary frequency, primarily for satellite and DX work.
* New Zealand: 144.575 MHz (National APRS) and 144.650 (digipeaters) — check with locals for details
* Argentina: 144.930 MHz
* Brazil: 145.570 MHz
* Europe: 144.80 MHz

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, 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 and the International Space Station 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 TNC’s, and “smart” TNC’s. The “smart” TNC’s are capable of determining what has already happened with the packet (unit of information) and can prevent redundant packet repeating within the network.

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. Three common models are the mobile Kenwood TM-D700A, its replacement, the Kenwood TM-D710A and the handheld Kenwood TH-D7A(G).

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,n8yyy.” 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 unncessary 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 RELAY, WIDE path to become obsolete. Users are being asked to configure “RELAY” stations as WIDE1-1. This results in a new, more efficient path of WIDE1-1,WIDE2-1.

  • Online Data

Much of the data transmitted over APRS can also be seen on the Internet. For a sample of what’s available, click on and enter the callsign of NJ2EM to see APRS activity in New Jersey. You can also zoom out to see activity and stations in other areas.

  • 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 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 most common use of the system.

  • 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 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.

eQSO

eQSO is a client / server software program designed by Amateur Radio enthusiasts for linking Amateur Radio RF gateways and repeaters via the Internet by using a Voice over IP protocol. This principle is also called Radio over IP. The software may be used by licensed Amateur Radio operators and Short Wave Listeners provided the rules are followed.

  • eQSO Indonesia

Sejarah

Luasnya wilayah Indonesia serta tidak terhubungnya repeater-repeater amatir radio membuat YB0KLI dan rekan amatir radio di maillist orari-news@yahoogroups.com menggagas ide VoIP untuk me-link repeater di seluruh Indonesia. Diskusi pertama muncul pada tanggal 25 Juli 2002. Pada tanggal 12 Agustus 2002 hal yang diidamkan akhirnya menjadi kenyataan; rekan-rekan di maillist ORARI News merasakan betapa nikmatnya berQSO dengan rekan amatir radio lainnya menggunakan sarana Internet. Saat itu server yang dipakai adalah server backup eQSO di alamat repeater.dns2go.com room Indonesia. Sistemnya disebut “Repeater Phone Internasional“.

Tanggal 29 Oktober 2002, ujicoba dilanjutkan secara on-air dengan menghubungkannya ke repeater YB0ZZ di Jakarta pada frekuensi 438.080 MHz dan juga beberapa gateway pribadi di beberapa propinsi. Hasilnya luar biasa… Komunikasi berjalan mulus, tak terasa lawan bicara ribuan kilometer jauhnya… Beberapa kontak bahkan terjadi secara lintas negara. Memang ada delay yang cukup mengganggu karena lokasi server yang jauh di belahan dunia lain. Beberapa waktu kemudian, server pindah ke alamat server.eqso.net room Indonesia. eQSO RF Gateway disediakan oleh YB0EO dan backup tersedia di QTH YB0HD. Tanggal 2 Juni 2003, server kena petir namun masih bisa dipugar dalam beberapa hari, namun 10 Pebruari 2004 layanan ini benar-benar padam karena PSU server jebol kena petir dan kendala sumberdaya lainnya termasuk mahalnya link Internet yang harus disubsidi selama 1,5 tahun, proyek ini akhirnya mati suri.

Setelah mati suri dan tidak puas dengan delay yang terlalu lama, akhirnya tanggal 1 Maret 2005 rekan-rekan kembali dapat menikmati eQSO. Ini kali kita membangun infrastruktur yang lebih “Indonesiawi” dengan server yang diletakkan di QTH YB0EO dan diakses melalui IP 202.155.147.155. Tanggal 3 Maret 2005, sistem ini dapat pula diakses dari jaringan WiFi ORARI dengan SSID “WiFi ORARI” atas bantuan dari YB0HD yang diletakkan di gedung BNI46, Jakarta. Tidak hanya itu, tanggal 7 Maret 2005, YD9ANL menyediakan backup server di IP 202.152.53.26 dan 202.162.208.213. Semua entry alamat IP digilir DNS menggunakan teknik round-robin yang memungkinkan sistem diakses dengan alamat tunggal server.aeroCity.net — bila satu server mati akan digantikan oleh server berikutnya. eQSO RF Gateway yang turut berpartisipasi adalah YD1SRP, YD0NPZ, YB0HD, YC1ZAC, YC5PDT, YB3CC dan YC3RCJ. Sistem ini tidak bertahan lama, domain aeroCity.net yang sedianya adalah nama layanan packet radio besutan YB0KLI harus kalah ditelan tingginya biaya maintenance; sistem ini hanya bertahan sampai 13 Pebruari 2006…

World LogoProyek eQSO Indonesia 2007 kembali mencoba mewujudkan mimpi lama untuk menyediakan jalur komunikasi alternatif bagi Amatir Radio di Indonesia dan menyatukan repeater-repeater agar kita semua dapat berkomunikasi lebih mudah. Soft launching dimulai pada tanggal 1 Januari 2007 dan launching ke masyarakat amatir radio Indonesia tanggal 3 Januari 2007. Kami berharap agar proyek ini dapat bertahan hidup lama serta berkembang sesuai perkembangan teknologi.

Tanggapan Organisasi

Saat ini, ORARI membuka diri terhadap eQSO. Gebrakan dimulai oleh amatir radio di Makassar dengan berdirinya Club Station yang khusus mengembangkan dunia digital di amatir radio. Callsign YB8ZD akhirnya terbit, dimotori oleh YB8EW dan kawan-kawan [baca situs webnya]. YB8ZD lahir tanggal 17 April 2007 dengan IAR yang diterbitkan oleh Dinas Perhubungan Sulawesi Selatan. Rakerda ORDA Sulawesi Selatan tanggal 12 Agustus 2007 telah menyiratkan pentingnya amatir radio mengikuti perkembangan teknologi.

YC1LZ melalui lobi yang intensif dengan pengurus ORDA Jawa Barat akhirnya menanyakan hal ini secara resmi ke ORPUS mengenai kegiatan eQSO. Melalui surat nomor B-171/OP/KU/2007 tanggal 10 September 2007 –tepat 1 hari sebelum diselenggarakannya eQSO Ramadhan net 2007– ORPUS menilai bahwa:

1. eQSO adalah pengembangan komunikasi digital yang digeluti amatir radio seluruh dunia termasuk Indonesia
2. Perlu adanya pemahaman yang jelas tentang pemaduan jaringan Internet dengan jaringan amatir radio sehingga tidak melanggar KM-49 Tahun 2002 tentang kegiatan amatir radio
3. Dengan akan diterbitkannya PP-38 Tahun 2007, ORARI dan Ditjen Postel sedang membahas hal-hal yang berkaitan dengan eQSO
4. eQSO dianggap sebagai kegiatan eksperimen amatir radio yang perlu mendapat pengawasan dan dikendalikan oleh ORARI Daerah.

Kondisi Terkini

Layanan dan situs eQSO Indonesia 2007 pada alamat eqso.orari.net di-hosting di salah satu server YB0EO. Dengan memori 2 GB, harddisk 200 GB serta koneksi gigabit Ethernet langsung ke port Indonesia Internet Exchange (IIX) berbandwidth 10 Mbps, layanan eQSO Indonesia 2007 dapat diakses oleh ribuan pemakai di Indonesia tanpa hambatan. Administrasi server dikelola oleh YB0KLI dan administrasi eQSO RF Gateway dikelola bersama oleh YD1SRP, YC1LZ dan YB8EW.

Pada tanggal 1 Nopember 2007, domain orari.net kadaluarsa dan proses pembaruannya menemui kesulitan teknis; ini menyebabkan layanan eQSO Indonesia 2007 terganggu karena pengguna tidak dapat menggunakan subdomain tersebut, harus menggunakan alamat IP langsung. Onno W. Purbo, YC0MLC, Litbang ORPUS membantu menyiapkan subdomain eqso.orari.or.id dan akhirnya subdomain ini hidup tanggal 9 Nopember 2007.


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