[Xastir] CAD object transmissions?

[Jason Winningham]

On May 16, 2007, at 6:03 PM, Craig Anderson wrote:
>
> That APRS channel
> could be co-resident with a TCP/IP over AX.25 KISS
> channel that I suppose could really be carrying the
> CAD objects.

TCP/IP is a connected mode point to point protocol, not really  
suitable for one-to-many communications.


> Functionally, I would like to have everyone be able
> to see the same picture and, in effect, treat the Xastir
> map as a shared blackboard.

this is pretty much what APRS is already....

> A CAD object with a
> small text string attached, even if that text string is only
> accessible by bringing up the "Station Info" on the object.

this is called the status text, an optional part of every position  
report.

There is also a messaging system with unicast, multicast and  
broadcast capability.

> We plan on running most of our frequencies other
> than 144.39 to reduce the clutter of all the other
> stations and avoid the overwhelming congestion
> of way too many digipeaters in some areas.

There's something to be said for maximizing bandwidth for your  
application, but there's also something to be said for taking  
advantage of the existing infrastructure.

Of course, you can do both - I have operated APRS on three different  
frequencies feeding a single instance of xastir; it's an easy way to  
increase available bandwidth.

> The ability to send out a "cancel" packet to remove
> a CAD object would be good.

it's already there - right click on the object in xastir to access  
the capability.

> I, myself, am not concerned about interoperability
> with other programs

well, APRS is _supposed_ to be a standard so that everyone can shoot  
at the same target.

> I'm imagining a HAZMAT incident in a town and the
> EOC starts marking off road closures, command posts,
> decon areas, shelters, and down-wind evacuation areas.
> Everyone can see the whole picture, just like a status
> board.  And others can add new problems to the board.

That's the basic idea behind APRS.

-Jason
kg4wsv