[aprssig] APRS SPEC Addendum 1.2 Proposals (compressed items & objects)

Bob Burns W9BU w9bu_lists at rlburns.net
Tue Mar 15 06:12:01 EDT 2016

Bob, this seems to be a “cart before the horse” problem.


The APRS specification should drive the equipment used in APRS, not the other way around. Granted, an installed base of 10,000 APRS devices is a concern. But, there has to be a better reason to deprecate part of the spec than just lack of support by one type of APRS client.


Also, the TM-D700 has been out of production about 9 years, I believe. While many of them may still be in use, they will gradually disappear from active use in APRS.





From: aprssig [mailto:aprssig-bounces at tapr.org] On Behalf Of Robert Bruninga via aprssig
Sent: Monday, March 14, 2016 8:36 PM
To: TAPR APRS Mailing List <aprssig at tapr.org>
Subject: Re: [aprssig] APRS SPEC Addendum 1.2 Proposals (compressed items & objects)


The reason the compressed objects were depricated is because there were about ten thousand APRS radios (D700’s) out there that could not decode them.  (Problem is, I lost my notes on what does and does not work… argh!)


But, if the idea is to have consistent performance and end-to-end communication in a tactical real-time network, it did not seem to be a good idea to have a built-in, known failure mode in a standard.


Also, the compressed format has no more precision than a regular object.  Its still to the nearest 60 feet.  Only the !DAO! protocol has increased precision.


If anyone has the exact list of what the D700’s or any other radio for that matter, do or do not decode, then maybe it is time to re-look at this.






From: aprssig [mailto:aprssig-bounces at tapr.org <mailto:aprssig-bounces at tapr.org> ] On Behalf Of Curt Mills via aprssig
Subject: [aprssig] APRS SPEC Addendum 1.2 Proposals


Regarding this web page:   http://www.aprs.org/aprs12.html
"Formats no longer recommended: Compressed-Objects, ITEM Format, Raw Weather Formats,"

I'd like to put in my thumbs-up for both Compressed Objects, and both Compressed and Non-compressed Items.

We've implemented these in Xastir and I find them of use in SAR. Compressed format gives much better precision in placing and/or recovering objects, precision you cannot get with non-compressed APRS formats. Items are useful for placing positions when you have no timestamp, as well as providing a shorter packet than APRS Object format.

In short, I see no advantage to removing formats that are currently used to good effect and already implemented in APRS programs.


Curt, WE7U

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