[aprssig] The best resolution of position from APRS

Robert Bruninga bruninga at usna.edu
Wed Jan 4 19:12:05 EST 2006

I think there is a big missunderstanding of what the 
APRS spec is.   THe purpose of the APRS Spec is
to provide a  Standard to assure ON air compatibility 
across all software and platforms and all users.  

It does NOT  hold anyone back except those who lack 
the creativity or willingness to use the ample free-fields 
provided for future expansion in just about every format.

That is why the !DAO! 1 foot precision was easy to
add to APRS1.2 to allow 1 foot precision while remaining
100% compatible with everything on the air.  And to 
assure 100% on-air compatibiilty to all users, is why
the compressed/object/item format was depricated
since at the time it was not implemented in most code
and was broken in others.

The purpose of the APRS spec is to provide a collection
of the protocol as implemented to assure cross platform
compatibility to all users.  I work hard to keep it that
way, while providing for any new and needed features
that will not obsolete the existing user base.

de WB4APR, Bob

>>> joe at lightningflash.net 01/04/06 12:07 PM >>>
Robert Bruninga wrote:
> 1) XASTIR insists on sending the depricated obsolete
> compressed object /item format that has been known
> to not work on the thousands of Kenwoods for many 
> years which  reprsents 85% of our mobile APRS community 
> that sees objects in their mobiles.  This undermines the
> communications on-air integrity of APRS when mobiles
> cannot see these objects.

No, Xastir insists on letting the users decide whether to do this or not. It 
is a user preference to send object/items in compressed format, and I 
believe the default is to avoid it. So a user has to explicitly turn this on.

> 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

What does KISS mode have to do with raw NMEA? You can change the MYCALL, 
send a raw packet, and change MYCALL back without any need for KISS mode.

Speaking of KISS mode, is the gold standard client aprsDOS going to start 
speaking it any time soon?

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

I thought !DAO! was APRS 1.2 spec?

> 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.

Sure is funny that declaring that something that was in the APRS spec for a 
very long time, but was recently taken out is "holding back progress". I 
guess when we look to APRS in the future, we should expect dumps of NMEA 
sentences on the air.

Ham radio is about experimentation and advancement of the art of radio 
communication. It's also about cooperation between all Hams in the ways they 
use the radio frequencies.

If someone is going to use some aspect of APRS that is not supported by some 
users' equipment, then that someone should know and understand the 
ramifications of use of that feature. But to say that there is no room for 
advancement of the principle of radio communication in APRS is kind of silly.

The key is education. Be aware of what you do. If you need to reach the 
widest audience possible, which includes Kenwood D700 and D7 users, then you 
should know what to avoid. If you are trying to communicate with a group 
that you know does not include such limited users, then there is no good 
reason to prohibit efficient, accurate communication among those users who 
are trying to communicate efficiently and accurately.

To assume that all APRS users are children who know nothing about anything 
and will "click every button" just for the sake of it is kind of insulting. 
Yes, there are users who choose not to educate themselves in the minutiae of 
APRS, but do not make us all cater only to that kind of user!

J. Lance Cotton, KJ5O
joe at lightningflash.net 
Three Step Plan: 1. Take over the world. 2. Get a lot of cookies. 3. Eat the 

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