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Mobile paths

 
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ka9vnv  
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Joined: 08 Jun 2004
Posts: 152
Location: Woodstock, IL

PostPosted: Thu Jul 29, 2004 9:39 pm    Post subject: Mobile paths Reply with quote

Answering a question in a thread from the Get Togethers section in the proper forum

Path selection is a rather localized thing, hence the confusing answers you've been getting.

In general, for mobile operations, you are most like going to be within range of a RELAY station, if anything. So, your first hop should be RELAY.

After that, you want to get to a WIDE - most RELAYs can be heard by a WIDE (or more capable) digipeater, so the next hop should be WIDE.

This path (RELAY,WIDE) works in most of the country, but there are some areas where it is considered bad karma. Illinois and most of the midwest do not fit that exception, so RELAY,WIDE is your starting point for around here.

Note that using RELAY,WIDE is also the only "mostly reliable" way to make the APRS/DOS feature of "Vicinity tracking(tm)" to work. It still requires a lot of things to happen just right, but this is more likely than not to work.

Beyond the first two hops depends upon your network. We have mostly WIDEn-n digis in the NIAN area for the wide-coverage ones. So, I use WIDE2-2 to finish my path. While driving around the area, RELAY,WIDE,WIDE2-2 is pretty reliable in getting to an IGATE, so that people can track me on internet, without getting ridiculous about the path.

Signed
Jeff Brenton KA9VNV

---
"It is not at all simple to understand the simple." - Eric Hoffer
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wb9woz  



Joined: 04 May 2005
Posts: 12

PostPosted: Tue May 17, 2005 7:41 pm    Post subject: mobile digi paths Reply with quote

Here is a perfect example of how RELAY1-1,WIDE3-3 would work for mobiles. This mobile was 121 miles from my qth. It also answers the question on ID call substitution from the tnc. So, maybe Bob does have a good idea here.

There is NOT a need for long paths for very good mobile coverage.

Would this generic path of RELAY,WIDE3-3 have made it to my qth prior to the local digi programming changes, or would it have gotten lost in all the RELAY,WIDE collisions. Who know, but the channel activity seems to have gone down a bit after the changes.

Bruce


N9IGS>APU25N,KC9DGP-10,WIDE1,N9IJ-10,WB9WOZ-15,WIDE3*:@172323z4352.34N/09112.58Wv180/037/A=000640 146,52, OR TEXT ME {UIV32N}
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wb9woz  



Joined: 04 May 2005
Posts: 12

PostPosted: Tue May 17, 2005 7:47 pm    Post subject: Re: mobile digi paths Reply with quote

wb9woz wrote:
Here is a perfect example of how RELAY1-1,WIDE3-3 would work for mobiles. This mobile was 121 miles from my qth.


N9IGS>APU25N,KC9DGP-10,WIDE1,N9IJ-10,WB9WOZ-15,WIDE3*:@172323z4352.34N/09112.58Wv180/037/A=000640 146,52, OR TEXT ME {UIV32N}


My error, the distance should read 221 miles.

Bruce
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ka9vnv  
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Joined: 08 Jun 2004
Posts: 152
Location: Woodstock, IL

PostPosted: Tue May 17, 2005 10:23 pm    Post subject: Reply with quote

Quote:
Would this generic path of RELAY,WIDE3-3 have made it to my qth prior to the local digi programming changes, or would it have gotten lost in all the RELAY,WIDE collisions. Who know, but the channel activity seems to have gone down a bit after the changes.


Understandable - no one is using "wide1-1" at the home stations, to speak of. A mobile using "wide1-1" as their first hop is going to find few stations, other than wide-coverage digipeaters, to digi their signal. Fewer stations trying to transmit equals less "hidden station" QRM. Should the world switch completely to "wide1-1" as a replacement for "relay", the QRM will return.

In the mean time, we have a false sense of "this is better!", because the true cause is hidden... APRS's original design is flawed, in that it does not scale any better than connected packet when there are hundreds of low-coverage stations competing for the ear of the few, coordinated, wide-coverage digipeaters.

The potential saving grace is to make the first-hop digis at least as smart as the wide-coverage digis. If you've made the investment in putting up a WIDE digi, you have tried to keep up with the "state of the art", or close to it, right? That meant moving to WIDEn-n when it became available, because it dealt with duplicates better.

But the home station operators, which makes up the bulk of the mobile coverage in many areas, haven't had that incentive. All they've been told is "make the RELAY alias available in your (potentially ancient) TNC, and all will be well with the world". Well, the world isn't liking that arrangement so much anymore!

My opinion on the matter, so much as it counts anymore, is that the "delayed relay" intelligence must be incorporated into as many APRS programs as possible, and those station operators as can be set up to use their TNCs in KISS mode, and let the APRS software implement the digipeating.
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AB9FX  



Joined: 31 Jul 2004
Posts: 23
Location: Chicago, IL

PostPosted: Wed May 18, 2005 7:11 pm    Post subject: Reply with quote

In my understanding RELAY was switched to WIDE1-1 because in Kantronics digis duplicate checking was not implemented for simple aliases (in UIDIGI command). As a result station with RELAY,WIDE2-2 was repeated by WIDE digi when heard directly and again coming from home stations. A packet comes to WIDE digi (A - home relay) as:
RELAY,WIDE2-2
A*,WIDE2-2
Then digi (for exemple W9XYZ) WIDE with KPC3+ (without dupe checking for UIDIGI) does:
W9XYZ*,WIDE2-2
A*,WIDE2-1
If RELAY is switched to WIDE1-1, WIDE digi does:
W9XYZ,WIDE1*,WIDE2-2 (heard direct)
Next packets coming from home relays are not repeated because dupe checking works for n-n in UIFLOOD or in UITRACE. All other copies are ignored.
Not perfect, but better. Home stations still give more traffic, but WIDE digis transmit just once the same packet.
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ka9vnv  
Site Admin


Joined: 08 Jun 2004
Posts: 152
Location: Woodstock, IL

PostPosted: Thu May 19, 2005 11:40 pm    Post subject: Reply with quote

Quote:
In my understanding RELAY was switched to WIDE1-1 because in Kantronics digis duplicate checking was not implemented for simple aliases (in UIDIGI command).


Quite true. But, what is the real penetration of KPC-3s with v8.2 or later software in the non-digipeater market? It's an expensive TNC to buy new. The v8.2 software provides few benefits for anyone running a home station that isn't also a wide-coverage digi. Version 8.3 of the Plus adds features for mobiles, not home stations.

This means a lot of MFJ-1270's and Paccom TNC-2 and ??? are going to be getting WIDE1-1 programmed as an alias, returning to the situation of lots of packets on the first hop. Sure, the wide-coverage digis won't digi it twice, at first, but they also might not hear it because of the others all squawking at the same time. Wink

I'm willing to play the game, though. The important thing to remember is not to tell people to put "wide1-1" in as the myalias or in the uidigi calls on a KPC-3, because that will probably cause problems, as it would keep the WIDEN logic from seeing those packets for dupe-checking.
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KK9H  



Joined: 29 Jun 2004
Posts: 40
Location: Northfield, IL

PostPosted: Thu May 26, 2005 1:27 pm    Post subject: Mobile path WIDE2-2 to and from Dayton Reply with quote

On my trip to Dayton last weekend I tried a simple WIDE2-2 path on my TinyTrak3. On the Thursday trip to Dayton we were in constant heavy thunderstorms and my GPS could not even acquire a signal for most of the trip. On the way home, the WIDE2-2 path worked perfectly all the way from Dayton. In fact, FINDU.com showed 173 position reports from early Sunday morning until I arrived home. Since I have my TT3 set for 2 minute intervals at highway speeds, there was 346 minutes of coverage (5 hrs. 46 min.) which is almost exactly how long it took to get home.

The recommended WIDE2-2 mobile path seems to work just fine.

Don KK9H
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W9GWP  



Joined: 01 Feb 2005
Posts: 10

PostPosted: Sun Jun 12, 2005 7:52 am    Post subject: Mobile path Reply with quote

Len N9IJ is on a trip south using a path of WIDE1-1,WIDE2-2 as a test to see how the network is "working". He has e-mailed me that where there is APRS coverage, the path is working very well. It appears that out South and East they have "converted" a great deal of stations. We are going to continue a few more tests on his return trip ( which will take a different route ). I'll be doing the same thing on my trip to North Dakota soon.
73,
George W9GWP
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KK9H  



Joined: 29 Jun 2004
Posts: 40
Location: Northfield, IL

PostPosted: Tue May 23, 2006 9:44 am    Post subject: Dayton trip Reply with quote

I ran a path of WIDE1-1,WIDE2-1 on my trip to Dayton and back this year. It worked just fine in getting me to FINDU.com from Chicago to Indianapolis and from Indianapolis to Dayton. There seem to be some well placed digi's along I-65 and I-70 so I would rate the coverage as quite good along this route. Two hops seemed to be all that was required which is also nice.

Don
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