[OZAPRS] IS Gating etc

Owen Duffy owen at owenduffy.net
Sun Sep 28 15:32:28 EST 2014

Hi Liz,

On 27/09/2014 6:37, Liz wrote:
> ...
> I gate some packets from APRSIS to RF. Using aprx, those packets are
> sent such they are not digipeated.
> I'm not sure which software Kim VK2ASY is using, (he was testing
> aprsis32 in March), nor if that software offers the choice to mark the
> packets from APRSIS not to be digipeated.
I did write to him on Monday last, and though he did not respond, it
appears that he has ceased gating his buddies back to RF with a path
length of 3 hops as the traffic here has HALVED since then (ie from just
over 1000 packets / hour during drive time to around 500 packets per hour).

Gating IS to RF is always a high risk activity, it must be carefully
filtered and then the outcome by observing logs (not always easy when
you give the packets a life of three hops as in this case.)

There will be competing views of the 'real purpose' of APRS radio
channels. The original purpose of position reporting (with priority to
moving stations) has given way to a more generalised messaging system
carrying all manner of traffic with dubious claims about the wider
community value.

The APRS channel carries its traffic as UI packets, packets are know
acknowledged or repeats requested if broken, they are just lost though
of course they did use channel time.

Because of this, the channel must run at low utilisation to preserve a
reasonable prospect that transmitted packet packets are received, they
there is not a collision with a packet from another transmitter which
might not be heard by the originating station and vice versa.

The notion of keeping channel utilisation low (by not filling it with
lower value traffic) is clearly an anathema to some.

A question that can be debated is whether posits for fixed and moving
stations are each higher value traffic. Many people would reasonably
question the value of 2 minute posits from a station that hasn't moved
in days, whoever it is.


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