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[aprssig] The best resolution of position from APRS

Curt, WE7U archer at eskimo.com
Wed Jan 4 17:57:32 UTC 2006


On Wed, 4 Jan 2006, Robert Bruninga wrote:

> 1) XASTIR insists on sending the depricated obsolete
> compressed object /item format

Xastir has an _option_ for enabling base-91 compression of posits
(which Kenwoods understand just fine so there's no problem there.
Bob doesn't have a problem with this either by the way.  Just making
things clear.

Xastir has an _option_ for enabling base-91 compression of
objects/items.  European Kenwoods (D700E, don't know about D7E)
appear to handle compressed objects ok.  North American Kenwoods
(D7A, D7A(G), D700A) just ignore them.  I don't think ANY Kenwoods
handle "Items", whether or not they're compressed.

My chart doesn't say whether Kenwoods handle mixed case objects.  If
they don't, will mixed-case objects be deprecated from the spec as
well?

All of the modes we're discussing, objects, items, compressed
objects, compressed items, were in the spec until July 2004, and
were being used on the air at times where the higher resolution or
the shorter packet/less airtime required it.


> 2) Yet there are 3 ways XASTIR could UPGRADE and
> transmit objects to 1 foot resolution if they wanted
> to instead of just bashing kenwoods.
>
> a) use KISS mode and send the object as a $GPGGA packet

KISS mode is irrelevant here, but I'd abhor sending any NMEA string
over the air as that is a total waste of bandwidth.  Those things
are LONG!


> b) Send the object in 3rd party format as a $GPGGA packet

Also a waste of bandwidth.


> c) IMplement the new APRS 1.1 !DAO! format.

And we will do so.  Later.  Notice that I didn't say that I would
take out the code to do the compressed objects/items, remove the
user togglebuttons to enable them, or change the default for them
(the default is to disable base-91 compression for the two
togglebuttons).  Choices are good.  People need to understand the
repercussions of their choices.  That's why we're having this
discussion (I think).


> To me, This insistnce on using the obsolete/depricated
> compressed object/item format is what is holding back
> progress, missleading the community, and bashing a
> very useful product that almost half of us depend on for
> our APRS picture.

I didn't see much Kenwood bashing going on, but saw a lot of Xastir
bashing, from you.  I've seen the discussions about Kenwoods many
times over the years, and they're always the same:  "Why can't
Kenwood fix the problems and/or implement more of the spec".
Eventually somebody will have to listen at Kenwood, else somebody
else will come along and outdo them and they'll lose their market.
The deficiencies in the Kenwoods are valid concerns Bob.  That's why
people keep bringing them up over and over again, year after year.

By the way, I think this is the first time _ever_ that anybody has
complained that Xastir is holding back progess.  I think it
hilarious.


> If these authors would instead update their software to
> the APRS 1.1 spec which does try to be responsive to
> user needs then ALL users will be able to see what is on the
> air at a come-as-you-are event.

We'll certainly try to implement more of the spec.  I think we've
done a pretty good job so far of it.  Doesn't mean we'll take out a
bunch of things we've coded up that were in earlier specs.  After
all, we want to be backwards compatible, right?

--
Curt, WE7U.   APRS Client Comparisons: http://www.eskimo.com/~archer
"Lotto:    A tax on people who are bad at math." -- unknown
"Windows:  Microsoft's tax on computer illiterates." -- WE7U
"The world DOES revolve around me:  I picked the coordinate system!"




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