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[aprssig] POI engine on APRS-IS (no engine required!))

Andre aprs at pe1rdw.demon.nl
Tue Feb 21 15:57:54 UTC 2012


Op 21-2-2012 16:42, Bob Bruninga schreef:
> NO POI/ITEM/OBJ engine needed!
>
> The existing ITEM-in-MSG format (with the wildcard sender's position option)
> can do everything we need here.  We do not even need a special server..
>
> 1) As originally intended, the ITEM-in-MSG format allowed for sending an
> OBJECT to a mobile RADIO via the global APRS-IS system.  Thus, every client
> that has implemented the ITEM-in-MSG format will already see this new
> object.  The original intent of this was for the AVRS engine to be able to
> send a FREQ object to a called party so he could see where to call.
>
> 2) This new use of ITEM-in-MSG for the mobile or handheld radio to initiate
> an object can use the same protocol!  But to make it handy, we simply need
> to add the wildcard character * to indicate that the sender's own posit be
> used.
>
> Beyond that one change, there is no special engine required, no timing
> algorithms, no acks, no nothing.  If the sender wants so send an OBJEC To
> another person, the protocol does that well and the message will be acked.
> If the sender wants to send it so that it is seen on the APRS-IS or other
> local clients, then he can send it to ITEM, POI, OBJECT, DF or any other
> made-up address he wants and it will be transmitted 5 times and stop.  This
> is exactly what we want.
>
> Now, to give the sender some condifence, it would be OK for APRS-IS clients
> to offer an ACK service such as if an ITEM is sent to "APRS.FI" as the
> message address, then APRS.FI for example could send back an ACK to give the
> sender the knowledge that it has been captured.  Hopefully APRS.FI already
> does process the ITEM-in-MSG format though it will need to be updated to
> recognize the LAT and LONG wildcard.
>
> Done?
>
> Bob, Wb4APR
>
>
But what LAT/LONG should be used for the wildcard? if you use the 
current position then you can only create objects that follows the 
sender, might as wel use the beacon comment and status for that, same if 
you use the last known position at the time the message is send, the 
object changes position each time the message is retransmitted as you 
never know if it is the first message or last.
The only way to create a fixed object is to ack it, that way the creater 
can stay put untill the item in message is acked and then move on 
knowing it is recieved at the place it is needed, if send to an POI 
server the server can adopt it and handle retransmitting, maybe even 
according to a setting that can be changed with commands, if send to a 
person they can adopt it if needed and restransmit as they see fit.

73 Andre PE1RDW



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