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Re: ISS Unproto Destination Address

On Tue, 25 Sep 2001, Stan Vandiver wrote about my suggestion that users
wanting their packets to be seen by everyone should use "CQ" as a tocall:

> If you want to rewrite the code, I would suggest removing the header
> filter instead.  APRS brought on this "problem"... by design.  You can
> make it better for the future, in my opinion at least, by making it
> "freestyle friendly" in future revisions.

The TOCALL in APRS is just like any other destination address in any other
comunication system.  If you want everyone to see your transmissions, then
use an ALL-CALL address of which there are many (CQ, QST, ALL, etc...)...
If you only want it seen by one person or a subset, then use another
callsign, or group callsign..

The TOCALL filter that you suggest be abandoned is fundamental to the
flexibility of APRS operations using the tremendous single frequency APRS
infrastructure worldwide.

Everyone can use the same digipeaters, the same Igates, and the same
satellites and a single worldwide internet distribution channel for their
own purposes because of the front-end TOCALL filters.  WIthout the filters
they would have to contend with thousands of packets per hour, instead of
the few they might be actually interested in.

If they want their packets to ONLY go to everyone working their
Marathon and not be bothered by any of the hundreds of other users on
channel, then they should set their TOCALL to RACE or some other
mutually agreed SUBNET.  If you only want your packets to go to AMSAT,
then address them to AMSAT.  But then you must tell others to open their
filter to AMSAT, or otherwise, it wont go to them.

With hundreds of users in any area all using the same frequency for APRS,
the presence of the front-end TOCALL filter is fundamental to APRS
operation to serve a variety of users, applications, and subnets while
ignoring everyone else on channel.

Thus the TOCALL of a packet should address who the packet is TO.  If it is
to ALL, then the ham radio typical calls of ALL, CQ and QST were built
into APRS for that purpose.  If you send a packet to BARRY, then in
accordance with the definiition of the AX.25 TOCALL, one would probably
conclude that the packet was intended for only one station named BARRY
or all stations with the group callsign of BARRY...

> If you want to rewrite the code, I would suggest removing the header
> filter instead.  APRS brought on this "problem"... by design.

Yes, it was by design.  And I hope you can now see that there is value in
using the TOCALL of a packet as an address and why this is not really a

Hope that helps


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