This page is always current with any changes to the APRS Spec: Although the APRS spec was nailed down in 2004, this page captures any details that were not in the original spec document. This page must be considered part of the spec. For Example, the SYMBOLS and TOCALLS are constantly being updated (almost montly) as applications and usage grows.
Updated 3 Nov 2011 to add the overlooked requierment for AutoAnswer messages to begin with AA: and to auto-cancel when the operator returns.
This copy of the APRS SPEC Addendum 1.1 was approved by the APRS-WG .
(Vote was called 30 July 2004).
This APRS1.1 page is always maintianed current such as the SYMBOLS and TOCALLS links below.
All new updates and additions to APRS since 2004 are found on the APRS 1.2 proposed draft addendum.
For a comparison of what has been implemented in what clients, please see the Capabilities Chart
APRS SPEC FINALIZED as of July 2004: This APRS Specification version 1.1 represents additions, corrections, and deletions since the original APRS1.0 spec of 21 June 2000. This edition represents the state of the APRS protocol and its usage through July 2004. As of this date, the state of the APRS users showed almost 27,000 stations worldwide of which:
APRS Mobiles: Of these mobiles, it is interesting to note that almost 60% are transmitting APRS using the Kenwood D7 or D700 APRS radios but more significantly nearly 85% of all mobile APRS users, who view APRS data in their vehicles, use these radios as their only source of APRS data while mobile. Thus, to the extent that APRS is intended for tactical-real-time local display of data to end users, compatibility with these mobile users is a significant driver in the consideration of changes to the APRS Specification. Another interesting observation is that about 55% of all APRS stations are firmware devices (digis, TNC's and trackers and WX stations) that are not easily upgraded. This is a testiment to the stability of the APRS protocol and our desire to maintain compatibility with existing users where possible.
APRS is NOT Ham Radio's MOBILE COMPUTING: The 1200 baud national APRS user channel cannot and was never intended to be Ham Radio's solution to Mobile Computing . The thousand-fold greater bandwidths required for typical Mobile Computing applications are enormous and there is no attempt to clutter the APRS channel with all possible data that might be of use to a user with a laptop in his car. APRS is for brief, short data types of immediate Ham Radio interest to all tactical users on the local RF channel.
APRS1.1: With the above as background, the following items represent the uncontested changes, additions, deletions or amplifying information included in APRS Specification Addendum 1.1. There is no intent to re-publish the spec. The original document will remain as is, and these APRS 1.1 revisions will refer back to appropriate pages where noted:
OBJECT (and NAME) CLARIFICATIONS:
UPDATED TABLES and INFO:
WEATHER RELATED ISSUES:
APRS-IS (Internet System):
APRS 1.1 SPEC Operating Conventions for the Good of the APRS Network:
The above is the complete APRS 1.1 Spec Addendum. It was a compilation of all the accumulated feedback from users and authors about errata, errors, typos and any omissions in the spec that had been accumulated from the time of the original spec to June 2004. This APRS erratta page had been running continuously for years and was updated whenever these items were discovered and each of these items were widely published and discussed on the APRSSIG and the APRSSPEC working group for public discussion. But it was decided best to finally Freeze the accumulation in June 2004 as APRS1.1 and then after public posting approve it.
Then to begin working on any new issues as APRS1.2.
See the proposals for APRS1.2
Bob Bruninga, Technical Chariman, APRS Working Group
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