[Xastir] Directed Station Query for Position?

[Tom Russo]

On Tue, May 10, 2005 at 03:39:53PM -0400, we recorded a bogon-computron collision of the <mckeehan at mckeehan.homeip.net> flavor, containing:
> It is my understanding that the General Stations Query asks all stations to
> respond by sending their position and status.
> 
> I'm looking to get a station to respond to me with his position using the same
> path to get back to me that I took to get to him; his normal path will not get
> back to me.

Try sending "?APRSP" as a message to the station.  Be prepared to cancel 
pending messages, though.  Xastir does not implement general queries other 
than the ones you can get to from the menus or the station info dialog (i.e.
the "general stations" "Igates" and "wx stations" queries for all stations,
and the "direct stations" "trace" and "unacked message" queries you can get to
from Station Info) --- using the message dialog to send queries works, but 
xastir treats them as regular messages: if you attempt to send "?APRSP" xastir 
will keep sending until it gets an ack, and no ack will ever come.

I just tried this --- I sent an "?APRSP" to the D700 in my truck from my 
APRS-IS-only office machine, and it responded with a posit immediately.  Watch 
for the incoming posit, kill the outgoing message when it comes in so you don't 
flood your local net with the query.  AFAICT, though, the returned posit used
the packet path my D700 normally uses, not a reverse path through the igate
and to me via APRS-IS as you hope it would be.

Ideally there would be a way to send specific types of queries outside of the
message dialog --- queries are not supposed to have message-IDs and are 
not supposed to be retransmitted the way messages will be if unacked.
I once thought it might be simple to hack on the message dialog handling
so that if the message was one of the queries in the APRS spec then it would
send it with no message ID and not queue it for retransmission.  Another
option might be to have a query dialog that sends any of the queries in the
spec with a click of a button to any specified station.

> On Tue, May 10, 2005 3:18 pm, Jason Winningham said:
> >
> > On May 10, 2005, at 2:15 PM, William McKeehan wrote:
> >
> >> I know there is a station on RF not too far from me. His packets do
> >> not make
> >> it to an IGate, and they are not being digied by any of the digi's
> >> that I can
> >> hear.
> >>
> >> Is there a way in Xastir to send a query packet to that station and
> >> have it
> >> return it's location to me via RF?
> >
> > Is that what message -> general stations query is about?  I think it
> > is...

I think "general stations query" is a broadcast "is there anybody out there?"
query, and is intended to cause all stations that hear it respond with a posit. 
AFAICT, few  clients actually implement this --- or at least none
in my area do, and Xastir doesn't respond to it (though it will send one).  
That's probably a good thing, as this is an easy way to flood an area with
tons of extra packets.

-- 
Tom Russo    KM5VY     SAR502  DM64ux         http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236 AHTB#1 
 "The only thing you can do easily is be wrong, and that's hardly
  worth the effort." -- Norton Juster