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[aprssig] APRS 3rd party question

Lynn W. Deffenbaugh (Mr) ldeffenb at homeside.to
Fri Feb 19 12:37:39 UTC 2010


Rob,

rfinesmith at aol.com wrote:
> I need some help understand tunneling and 3rd party packet types.  I 
> would like to create and send a tunneled packet to APRS-IS and have 
> it transmitted over RF by a specific igate.  The packet will contain 
> an APRS object (not a message type of packet) to be sent direct, or 
> via one hop after the igate.
>  
> Is this possible, and can someone provide an example of the source 
> path header I would need to accomplish this?

My understanding is that the APRS-IS doesn't transport 3rd party 
packets.  They exist only on the RF side when an IGate takes "stuff" off 
of -IS and sends in on RF.  "Stuff" is whatever the IGate owner has 
configure to gate from IS to RF.  This is typically messages, sometimes 
special objects, sometimes specific callsigns.  As far as I know, there 
is no way for a 3rd party to get stuff to gate from IS to RF via a 
remote IGate without the IGate owner configuring it to do so.

That being said, there's a spec for "Item-In-Message" 
(http://www.aprs.org/aprs12/item-in-msg.txt) that allows an APRS 
item/object to be sent to a specific station embedded inside an APRS 
message.  Since most transmitting IGates DO gate messages from IS to RF 
for stations that have been "recently" heard "locally", this could do 
the job.  The problem with this is that it depends on support in the 
receiving client to support this new spec.

My APRSISCE for Windows Mobile and Win32 supports this spec.  I don't 
know of any others at this point but I'd love to learn via this list.  
Here's a few message texts I've sent to my client to have objects appear 
on the maps (this is the body of the message text):

)GC1TX0D!2800.38N/08039.03W.Turtle House D1.5T2.0
)GC1RDVK!2805.13N/08036.32W.Hero Cache D1.5 T2.0
)GC1EK82!2805.02N/08037.10W.Parking Fee D1.5 T1.0
)GC1R0N6!2804.98N/08037.34W.STP #43 D1.5 T1.5
)EL400494!2808.58N/08041.78Wr146.460 T136.5 W9PQ-L EchoLink/IRLP Node
)TRACK!5442.77N/00313.63WbDirt Racetrack?
)TREE!2758.44N/08033.86W.Tree


Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

PS.  To try out this newly developing client, join the APRSISCE Yahoo 
Group at http://groups.yahoo.com/group/APRSISCE/


>  
> Many thanks,
> Rob, AA3NJ
> ------------------------------------------------------------------------
>
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