[aprssig] Internet to RF gating of positions

Pete Loveall AE5PL Lists hamlists at ametx.com
Wed Sep 3 09:28:32 CDT 2008

The original "design" of APRS-IS was to allow for display of amateur radio APRS information on APRS clients connected to the Internet.  Internetwork messaging was added to allow hams to be able to communicate regardless of location (RF and/or Internet).  To help facilitate messaging, passing of the sending station's posit was also included when gating to RF.  Originally, this was the "last heard" posit but because of the high activity on APRS-IS (+32,000 stations) and server-side filtering, this was migrated to "next heard" (also to prevent stale data from creating loops and inaccurate tracks).  This gating to RF was restricted to messages and associated posits to reduce loading on the RF network where the gating is occurring.

Most IGate software allows for various "forced" gating to RF.  These can be objects, all packets from a particular station, etc.  This "forced" gating is how packets like area NWS objects and messages get gated to RF.  This is at the discretion of the individual IGate operators so they can account for local conditions such as RF activity and gating only information that is of interest to the local amateur community.

At one point, there was experimentation with sending a significant amount of non-amateur information (METAR, fire, buoy, etc.) to APRS-IS.  It was generally agreed at that time that this type of voluminous information (non-ham readily available elsewhere) was better served on a different subnet where people could access the information if they wanted and still participate in APRS-IS.  That subnet is FireNet and that subnet is still supporting that extra information.  It was expressed by the majority of posters at the time that a server-side range filter should be showing amateur activity, not a lot of non-ham activity.

Hope this clarifies how gating to RF works and how APRS-IS is configured today.  More information on APRS-IS and its operation can be found at www.aprs-is.net


Pete Loveall AE5PL
pete at ae5pl dot net

> -----Original Message-----
> From: Chris Kantarjiev
> Sent: Wednesday, September 03, 2008 9:02 AM
> To: aprssig at lists.tapr.org
> Subject: Re: [aprssig] Internet to RF gating of positions
> >  As the system was
> > designed, only MESSAGES can go to RF automatically (without
> > sysop intervention).
> I ran into this problem about 18 months ago when I tried to build
> a system that would look for traffic problems (via the publicly
> available loop sensor data) and post it to RF. I could never
> figure out a way to reliably get the data into the ether - and
> also couldn't be sure that I could force those objects to be
> deleted once the traffic cleared.
> This is a real problem. Not only do we need a design, we need
> to figure out how to get it widely implemented...

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