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

Curt Mills curt.we7u at gmail.com
Tue Mar 15 10:32:48 EDT 2016

On Mon, Mar 14, 2016 at 5:35 PM, Robert Bruninga via aprssig <
aprssig at tapr.org> wrote:

> 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.

You may wish to re-examine the spec on that one. We implemented a nice
little red bounding box in Xastir that bounds where the station is based on
the type of sentence sent. For non-compressed it's about 40' x 60' where I
live, compressed is 2' x 3'. The bounding box also indicates which
directions from the plotted symbol the station may be located in.

> 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.

D700's/D710's are fine for those who have them. I don't believe there are
any in our SAR organization so it's not a controlling factor. Even if we
did, the controlling factor would be the type of rig/software installed in
the command truck. We don't spend much time driving anyway: We're mostly on
foot or at command.

Curt, WE7U
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