[Xastir-dev] xastir as pvd

[Wendell Turner]

Curt Mills wrote:
> On Wed, 14 Apr 2004, Owen DeLong wrote:
> > Ah... I misunderstood your desire.  I thought you were trying to use XASTIR
> > as a MFD within the flight simulator.

Well, that would be nice also.

> > A couple of questions come to mind... This sounds like a perfect
> > fit with the internet APRS formats,

But we're back to the symbology thing.  Those little icons in
the APRS table just don't seem accurate enough for headings,
even if rotated.

> > except for your insistance on UDP.
> > Is there a reason you can't do TCP?

Well, I only wrote IP and UDP for our radios, not TCP.  I
realize that
that is no reason to alter xastir, but it sure would make my
application
much easier.  There would be no connection setup or keep-alive
tcp baggage,
xastir would just listen to a UDP port and display anything
received on it.

> > If you can do TCP, then, you could spit out APRS format messages (basically
> > NMEA with an AX25 wrapper), and you'd have callsign, altitude, course,
> > speed,
> > and just about any data you wanted.

Well, I could certainly write a gpsd-like thing to convert UDP
to TCP
if that is the only way to get data into xastir.

> > I think you can do it with minimal additional code in XASTIR.

I hope so!

> > I think if you can do TCP and pretend to be an internet APRS feed, you
> > then only need to add functionality we already want in XASTIR, but haven't
> > had time to implement:
> >
> >       Symbol Rotation
> >       Alternate Symbol Library
> >       Over-the-air Symbol definition

Have I just volunteered for those???

> That's how I see it as well.  Perhaps if the remote end only does
> UDP then you could create a shim program that provides a TCP
> listening socket for Xastir to connect to.  That way no changes to
> Xastir's main processing loops or interfaces would be required.

Yes, as above.

> You said the format wasn't all that critical, so perhaps the type of
> connection isn't either?

UDP is a whole lot easier if you have to write it yourself.  I
just don't
have TCP in the radio, and have all sorts of problems with tcp. 
Udp just
seems easier to work with.

> Do you need high accuracy, or is DD MM.MM format enough?

High accuracy.  I would want to show the difference in having
WAAS and not having it.

> The symbol rotation should be able to be tweaked internally without
> messing with different packets.  We usually have the direction
> within one or two degrees,

That would be fine.

> The alternate symbol library is the biggie.  This would benefit
> everybody if we did it correctly.  If it's done quickly, without
> much thought, it might not benefit anybody.

Well, given that, I suppose we should do it correctly(!).

> Do you absolutely need additional symbols at this point, or are the
> small/large aircraft and the helo symbols that we currently have
> adequate, if they can be rotated in finer increments?

I would really desire finer symbols, if that fit into the xastir
framework nicely.  Having a dynamic symbol may allow for items
such
as projected heading/speed barb in front of the symbol.

Wendell

(Will be offline tomorrow; out flying!)