Re: Igates and their use of digi paths

Lynn Deffenbaugh

Reply and questions interspersed below...

On 6/16/2020 3:05 PM, Justin Cherington wrote:

I’m trying to wrap my head around two way igates and if they generally use digi paths to increase their IS to RF ranges. In the SW we generally have igates in the cities/towns and wide area digi’s in the mountains.

This is true 'nuff.

As a two way igate, if a station 80 miles away (easily just one hop) transmits a message and I gate it, how do I get the response back to that station when the recipient replies?

IS to RF gated packets use the same path that you have configured for the IGate's beacons.  So, whatever you have in Configure / Beacon / Path... is the path that will be used on the 3rd party packet gated from IS to RF.  The theory is that the path will be set to something reasonable for your RF environment and that same environment is where you're injecting the gated packets.

In APRSIS32, I set the filter to let’s say 20 miles because that’s my direct range.  But that seems to be a disservice to the stations 80 miles away using digi’s, and I’m the closest igate to them.

What "filter" are you setting to 20 miles?  There is no distance filter that affects IS to RF gating.  It is strictly based on "recently" heard "local" where recent defaults to heard in the past 30 minutes and local means no more than 2 used hops in the "closest" received path from a station.  And these are hard-coded and not (yet) user-settable.

That said, you can affect the definition of "used" hops by setting appropriate aliases in Configure / Aliases / Known.  If SSn-N aliases are in use in your area, or any other aliases for that matter, you should have them listed in there so they are not counted as "used", but only the true digipeaters inserting used in the path are counted. 

Am I missing something? I don’t want to increase qrm needlessly, but the hikers, hunters, and off roaders need love too. Thanks!

Set an appropriate path for your IGate based on your local RF environment and you shouldn't be generating QRM.  Unless, of course, you're messing around with the Control-G / Control-I filtered gating of all matching APRS-IS packets to the local RF.  Someone was doing that in New Jersey and I got called out for "pushing" my lightning packets from firenet to their RF!

Note that you do not need any special filter to gate messages from APRS-IS to RF for recently heard local stations.  That is automatically an IGate function in APRSIS32 with the default Port settings for any instance with an RF and -IS port active.

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

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