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[aprssig] Fill-in Digis, routes in California

Cap Pennell cap at cruzio.com
Mon Mar 27 08:50:55 UTC 2006


Congrats on the new ticket, Allan KI6CRM!  Some more reply below.

> -----Original Message-----
> From: aprssig-bounces at lists.tapr.org
> [mailto:aprssig-bounces at lists.tapr.org]On Behalf Of apratt at bestbits.org
> Sent: Friday, March 24, 2006 17:06 PM
> To: aprssig at lists.tapr.org
> Subject: RE: [aprssig] Fill-in Digis, routes in California
> 
> 
> Cap! Good to hear from you. We met at the ham show in Monterey earlier
> this year. I asked you what route to use in northern CA and I got my
> license by passing the test that day.

Yes, we had fun demonstrating VHF and HF winlink operation (slow email via ham radio) there www.radiofest.org at the old Fort Ord in Seaside on Feb.25 and the APRS demo was on the table next to us.  I remember speaking with you then, just before you went in for your exam session.  Fine business!

> Are you saying that there is no place in CA that is three hops from an
> IGate? That is, you're either 1-2 hops away or out of luck completely?
> Not in the cities - I'm talking remote areas: Trinity National Forest,
> the North Coast, Lassen County, the Eastern Sierras, and the Desert
> Southeast, from Ridgecrest and Death Valley to Borrego Springs.

As Stephen WA8LMF already replied, basically yes, if a modern two hop VHF digipath doesn't get you into the APRS-IS (Internet Stream) from California, a three hop digipath probably won't either.  Most of our "n-N" digis are still at high elevation, and are heard by an IGate station.  Many commuters find a one hop path is sufficient for their purposes.
 
> My goal is to be tracked on findu as I travel in those remote areas.
> The way I look at it, a great tragedy is to finally peek through the
> terrain and hit a distant digi, only to have my packet die of hop
> count death before it reaches an IGate. That's why I contemplate
> running a 3-hop path on those trips.

If you suspect that is happening (perhaps due to a phone call with your intended internet "audience" back home? hi hi) there's no problem with trying WIDE1-1,WIDE2-2 for as long as you're paying attention on a back-country trip, as long as you don't leave it that way when no longer paying attention (commuting).  Every user can use as much as they need of the VHF network's limited available airtime, as long as the other users share nicely by not using more than they need.

> Bob's New n-N paradigm page at
> http://eng.usna.navy.mil/~bruninga/aprs/fix14439.html has a California
> map (http://eng.usna.navy.mil/~bruninga/aprs/ca-hops.jpg) which is ten
> years old. It shows three-hop areas between 101 and Highway 1 out to
> Bodega Bay, and also in Yreka and even along I5 south of Redding.
> There are vast empty areas too. No idea what the true situation is
> now, ten years later.

Yes, that's a nice map (Thanks, James!) and I'd like to see a newer version too.  But it only shows where stations were heard, not where no stations were heard.  Yes, there still are some empty areas _without any_ VHF digi coverage and always will be, especially narrow steep largely unpopulated canyons.  But if you're traveling you're not likely to be in them for too long.

> On the other hand, it sounds like you're saying that a three-hop path
> will be trapped in urban areas where one hop is enough. Does the TRAP
> logic mean it won't be digipeated at all? Or does it mean it'll repeat
> once, and therefore hit an IGate?

Yes, the latter, it will be transmitted (but showing no more available hops).  The local IGate will still see it coming from the "trapping" digi (appearing to have a "used up" path). 

> If your trapping causes my rude 3-hop packet to be repeated just once
> in urban areas, that sounds perfect to me: it means I'm not being all
> that rude after all. I could run 3 hops all day knowing I'd really get
> 3 hops where I needed it, but I would get 1 hop in the cities where
> one is enough.

Yes, but not enough of our digis are limited to two hops (WIDE2-2) that way yet.  Only those showing "W2" in their position comment work that way.  If the "S overlay on map symbol" modern WIDEn-N digi indicates "Wn" instead of "W2" in it's position comment then it doesn't trap WIDE3-3 that way.

> Is that how California works? Would be sweet if true, for my intended
> application. Thanks.

The North American "New n-N Paradigm" is already helping our stations (a lot) to conserve our limited available airtime on VHF in California, but unfortunately it's still not universally implemented yet.  Some digis (and users) still need settings updates for courtesy.  Particularly those still having a "N overlay" on their digi map symbol.  Their big dis-courtesy is not that those old-settings digis fail to include their callsign in the "digipath history" (the old system) so nobody knows they digipeated anything, instead it's that with their old settings they don't allow the distant _second_ hop of the modern WIDE1-1,WIDE2-1 mobile digipath AT ALL.  Instead, with their obsolete "UIFlood WIDE,30,NOID" setting they then "anonymously" _trap_ everything after the initial WIDE1-1.
73, Cap KE6AFE

Allan, if you haven't already, I hope you will consider subscribing to the California APRS Users mailing list (and invite all your APRS friends).  News and discussion about APRS in California (and nearby portions of adjacent states) will continue there.  The NEW and future:
http://groups.yahoo.com/group/ca_aprs/
Subscribe: ca_aprs-subscribe at yahoogroups.com
Post message: ca_aprs at yahoogroups.com


> -- Allan Pratt, apratt at bestbits.org






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