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[aprssig] questions about the Bulletin Screen "billboard" concept

Andrew P. andrewemt at hotmail.com
Wed Nov 9 00:38:01 UTC 2011

Greetings, all.

I have some questions for WB4APR, about his concept of the Mountain-Top Billboard display mode that the specs say an APRS client should support (but apparently few do).

How exactly should this information be presented to the human users? The spec talks about multi-line bulletins, but I can't figure out how the multiple lines are uniquely identified and ordered (other than when in NTS format, pg. 75 of the APRS 1.01 spec). The rest of it more or less makes sense, but please check my understanding (before I waste a lot of time writing software that behaves incorrectly):

1. Amateur radio bulletins and announcements are identified by the combination of the sending station callsign, the fourth character of the addressee field (which bulletin or announcement), and the 5-character group ID (which may be 5 spaces for non-grouped distribution). Because of the fourth character limitations, any one sending station is restricted to a maximum of 10 active bulletins (0 to 9) and 26 active announcements (A to Z).

2. National Weather Service bulletins use a totally different addressee format, which "sort of" can map into the above bulletin identifying logic, but not very well (by item #1 analysis, they would appear as only one bulletin '-' per group ["WARN", "WATCH", etc.], updated frequently with new content). Do they support multi-line?

3. Are there any other special categories that should be treated differently than just directly addressed messages? Should messages directly addressed to the receiving station be posted on the bulletin screen?

4. The status display for bulletins should display each bulletin's 1-line messages consolidated together in order, with some higher-order sorting of whole bulletins and announcements. What is the recommended default sort order for whole bulletins, in order of precedence? Time of last update? Callsign? Bulletin/announcement ID?

5. The bulletin board display should alert users when it is updated with newer information. Does this include "no-op" changes (receiving identical message text from a periodic re-broadcast)?

6. Presumably, directed station queries (APRS1.01 pg. 79) should _never_ appear on the Bulletin Screen.

7. Bulletins and announcements only stop showing up when the originator stops sending them.

Also, for directly addressed messages with sequence numbers, should the software immediately acknowledge receipt autonomously, or should it wait for a human being to explicitly tell it to acknowledge receipt?

Are there any updates in the APRS 1.1 or 1.2 specs that override any of the above?

Looking forward to some good advice.

Andrew Pavlin KA2DDO
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