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

Robert Bruninga bruninga at usna.edu
Mon Mar 14 20:35:40 EDT 2016

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

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] *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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