{"id":18761886,"url":"https://github.com/wb2osz/aprsspec","last_synced_at":"2026-02-06T13:40:23.001Z","repository":{"id":248151905,"uuid":"824786918","full_name":"wb2osz/aprsspec","owner":"wb2osz","description":"The APRS Documentation Project: APRS Protocol Specification 1.2, Understanding APRS Packets, How to Get Started in APRS, The Best APRS Presentations, etc.","archived":false,"fork":false,"pushed_at":"2025-07-11T18:48:48.000Z","size":16989,"stargazers_count":47,"open_issues_count":3,"forks_count":6,"subscribers_count":9,"default_branch":"main","last_synced_at":"2025-07-16T08:37:01.969Z","etag":null,"topics":["aprs","digipeater","igate"],"latest_commit_sha":null,"homepage":"","language":null,"has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":null,"status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/wb2osz.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":null,"code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null,"governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null,"zenodo":null}},"created_at":"2024-07-06T00:27:22.000Z","updated_at":"2025-07-16T01:13:31.000Z","dependencies_parsed_at":"2024-09-06T23:28:25.668Z","dependency_job_id":"2beac854-4fd3-4987-afd8-9d7e3c4536fd","html_url":"https://github.com/wb2osz/aprsspec","commit_stats":null,"previous_names":["wb2osz/aprsspec"],"tags_count":0,"template":false,"template_full_name":null,"purl":"pkg:github/wb2osz/aprsspec","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/wb2osz%2Faprsspec","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/wb2osz%2Faprsspec/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/wb2osz%2Faprsspec/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/wb2osz%2Faprsspec/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/wb2osz","download_url":"https://codeload.github.com/wb2osz/aprsspec/tar.gz/refs/heads/main","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/wb2osz%2Faprsspec/sbom","host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":266631545,"owners_count":23959419,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2022-07-04T15:15:14.044Z","status":"online","status_checked_at":"2025-07-23T02:00:09.312Z","response_time":66,"last_error":null,"robots_txt_status":null,"robots_txt_updated_at":null,"robots_txt_url":"https://github.com/robots.txt","online":true,"can_crawl_api":true,"host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["aprs","digipeater","igate"],"created_at":"2024-11-07T18:18:07.861Z","updated_at":"2026-02-06T13:40:22.983Z","avatar_url":"https://github.com/wb2osz.png","language":null,"funding_links":[],"categories":["Others"],"sub_categories":[],"readme":"# The APRS Documentation Project\r\n\r\nIt's hard to find good information on APRS.  A web search produces mostly outdated misinformation and little of value.  This is the beginning of a collection of the essential documentation.\r\n\r\n## What is APRS?\r\n\r\nIn the words of its creator:\r\n\r\n\u003e “**APRS is not a vehicle tracking system**. It is a two-way tactical real-time digital communications system between all assets in a network sharing information about everything going on in the local area. On ham radio, this means if something is happening now, or there is information that could be valuable to you, then it should show up on your APRS radio in your mobile.” \r\n\r\n -WB4APR (SK)\r\n\r\nRead more:  [What-is-APRS.pdf](https://github.com/wb2osz/aprsspec/raw/main/What-is-APRS.pdf)\r\n\r\n## The Best APRS Presentations\r\n\r\nClub meetings and ham conventions are always looking for speakers.  There was nothing about APRS during the 2024 Dayton forums.\r\n\r\nSuppose you wanted to give an APRS presentation at a club meeting or ham convention.  But...\r\nIt's a big job. You are not sure where to start and would like to use / adapt something already done rather than starting from nothing.\r\n\r\nWhere can you find suitable presentations?  I’ve tried searching and could not find much that was worthwhile.\r\n\r\nI’m throwing this out as a challenge to the APRS community.  Please help to make a list of the best presentations that others could use.  \r\n\r\n[The-Best-APRS-Presentations.pdf](https://github.com/wb2osz/aprsspec/raw/main/The-Best-APRS-Presentations.pdf)\r\n\r\n## How to Get Started in APRS\r\n\r\nHow can a newcomer get started in APRS?  \r\n\r\nA web search produces mostly:\r\n\r\n- Very specialized such as the configuration of a specific radio.\r\n- Outdated information.  (e.g.  you must buy a legacy 1980s style TNC or references to software apps abandoned decades ago)\r\n- Only talks about trackers and aprs.fi.\r\n- Leads you to believe that buying a very expensive radio is only way to get started. \r\n- Overly technical information such as the protocol specification. \r\n- Very brief description with a link to [aprs.org](http://www.aprs.org/) which would scare a beginner away.\r\n\r\nIf you search YouTube, the top of the list is “APRS The Most Worthless Mode in Ham Radio”   with APRS = a pile of poo in the picture.  That’s not a good first impression.\r\n\r\nThere is some very good material out there, but how can the newcomer find it among all the clutter?\r\n\r\n[How-to-Get-Started-in-APRS.pdf](https://github.com/wb2osz/aprsspec/raw/main/How-to-Get-Started-in-APRS.pdf)\r\n\r\nThis is a crowd-sourced list of the best resources for a beginner.  I need YOUR help to find the best resources.\r\n\r\n## *** Recommended Reading for all APRS Users ***\r\n\r\nWhat does this mean?\r\n\r\n    N83MZ\u003eT2TQ5U,WA1PLE-4*:`c.l+@\u0026'/'\"G:} KJ6TMS|!:\u00260'p|!w#f!|3\r\n\r\nWhat is wrong with this packet?\r\n\r\n    WA2GUG-15\u003eTQ0V4V,TCPIP,WA2GUG-15,K1EQX-7,N3LLO-3,WIDE2*,RFONLY,NOGATE:}KB1CRN-14\u003eTQ0V4V,WIDE1-1,WIDE2-1,WB2ZII-13,TCPIP,WA2GUG-15*:`e4Tp,Pu/`\"4/}Keep on truckin`_1\u003c0x20\u003e\r\n\r\nYou could try to digest the APRS Protocol Spec but that would probably give you an upset stomach.  And a headache.  A more gentle introduction can be found at:  [Understanding-APRS-Packets.pdf](https://github.com/wb2osz/aprsspec/raw/main/Understanding-APRS-Packets.pdf)\r\n\r\nBe sure to read the part about the mistakes that people make.  Read this carefully if you don't want to end up as an example of what not to do.\r\n\r\n## APRS Symbols\r\n\r\nReference table with Icons and on air encoding,  \r\n[APRS-Symbols.pdf](https://github.com/wb2osz/aprsspec/raw/main/APRS-Symbols.pdf)\r\n\r\n\r\n## APRS Thursday\r\n\r\nAPRS Thursday is a net managed by Michael KC8OWL, held every Thursday with the aim of growing message activity on APRS across the world.  Many manufacturers are now including APRS functionality as a standard feature, making APRS more accessible, and hopefully more popular than ever.\r\n\r\nThe APRS Thursday net is held each week on Thursday between the hours of 00:00:00UTC to 23:59:59UTC.\r\nBased on your browers locale, you can check into the net each week anytime between and in your local timezone. \r\n\r\nFor more information see:  [https://aprsph.net/aprsthursday/](https://aprsph.net/aprsthursday/)   or    [https://aprs.to/events/aprs_thursday/about/](https://aprs.to/events/aprs_thursday/about/) \r\n\r\n## Contact the International Space Station (ISS) with APRS\r\n\r\nDid you know that the International Space Station (ISS) and some amateur satellites carry APRS digipeaters?  You don’t need fancy equipment to use the ISS digipeater.  I saw a video where someone was successful with an HT and a quarter wave whip antenna.  Of course a better antenna will increase your chances of success.\r\n\r\nDetails:  [APRS-Digpeaters-in-Space.pdf](https://github.com/wb2osz/aprsspec/raw/main/APRS-Digpeaters-in-Space.pdf)\r\n\r\n## APRS Protocol Specification 1.2\r\n\r\nThe APRS Protocol Reference 1.0.1 was developed by the APRS Working Group and published in 2000.   A**PRS101.PDF is obsolete** and should not be used for implementation.\r\n\r\nIn 2004, the Working Group approved a list of corrections, clarifications, and new features summarized here:  [http://www.aprs.org/aprs11.html](http://www.aprs.org/aprs11.html). Unfortunately they were never merged back into the original document.\r\n\r\nSince that time all we have is a bunch of \"proposals\" from Bob WB4APR (SK) found at [http://www.aprs.org/aprs12.html](http://www.aprs.org/aprs12.html).   Some of the features have been widely implemented, others are just ideas for discussion that never went anywhere.  There is no dividing line.  Some of the links point to places that no longer exist.\r\n\r\nAPRS is still alive and well a quarter of a century later, with many new products, computer applications, and creative uses.  Implementation is more difficult and error prone with the information scattered around and incomplete.  Some people, trying to implement APRS, might not even know there were any updates since the original.  \r\n\r\nThis is an independent compilation of the original specification and all of the relevant updates since 2000.  This is not endorsed by the APRS Working Group.  The position of the APRS Working group is that the “official” version is still the original document and Bob’s version of the errata on his site. \r\n\r\nFeedback is welcome.\r\n\r\nNaming convention:\r\n\r\n[APRS12b.pdf](https://github.com/wb2osz/aprsspec/raw/main/APRS12b.pdf) is DRAFT b of version 1.2.\r\n\r\n[APRS12c.pdf](https://github.com/wb2osz/aprsspec/raw/main/APRS12c.pdf) is DRAFT c of version 1.2.  etc.\r\n\r\nA release version will drop the letter at the end.  \r\n\r\n## AX.25 Protocol Specification 2.2, fourth edition\r\n\r\nAPRS is generally transmitted as AX.25 Unnumbered Information (UI) frames. \r\n\r\n[https://www.ax25.net/AX25.2.2-Jul%2098-2.pdf](https://www.ax25.net/AX25.2.2-Jul%2098-2.pdf)\r\n\r\nLoRa APRS uses plain text with the TNC-2 monitoring format.\r\n\r\n\r\n## Minimizing APRS Collisions\r\n\r\nThe document \"Minimizing APRS Collisions\" focuses on strategies to reduce collisions in Automatic Packet Reporting System (APRS) networks.  By implementing these strategies, APRS networks can achieve better throughput and minimize collisions. \r\n\r\n## APRS Digipeater Algorithm\r\n\r\nThe APRS Working Group never produced an APRS digipeater specification.  Probably because existing 1980s style packet radio TNCs were being re-purposed at the time.    Someone wanting to implement a digipeater  had to piece together clues from various places and imitate poorly documented legacy 20th Century TNCs developed long before the advent of the [WIDEn-N paradigm](http://www.aprs.org/fix14439.html).  As a result, we see inconsistent, and sometimes very wrong implementations.\r\n\r\nHere is my attempt to clear up the confusion.  [APRS-Digipeater-Algorithm.pdf](https://github.com/wb2osz/aprsspec/raw/main/APRS-Digipeater-Algorithm.pdf)\r\n\r\n## APRS IGate Description\r\n\r\nInformation about developing an APRS Internet Gateway (\"IGate\") exists but it is a little sparse.  For now, see [Successful-APRS-IGate-Operation.pdf](https://github.com/wb2osz/direwolf-doc/raw/main/Successful-APRS-IGate-Operation.pdf)  for supplemental information.  Just ignore the parts mentioning direwolf.  Eventually, I should have a more generic version not revolving around one implementation.\r\n\r\n## Feedback\r\n\r\nThe UNOFFICIAL Protocol Specification compilation is a DRAFT version with known issues.  Your feedback is welcome.  Errors and suggestions for improvement should be reported here: [https://github.com/wb2osz/aprsspec/issues](https://github.com/wb2osz/aprsspec/issues)   for tracking.\r\n\r\nGeneral discussions about the APRS Protocol should go to the discussion forum  [https://groups.io/g/APRS](https://groups.io/g/APRS)\r\n\r\n73, John WB2OSZ","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fwb2osz%2Faprsspec","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fwb2osz%2Faprsspec","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fwb2osz%2Faprsspec/lists"}