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Northern Illinois APRS Network Home discussion group for NIAN
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Sonny
Joined: 25 Nov 2004 Posts: 1 Location: Chicago
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Posted: Thu Nov 25, 2004 12:55 pm Post subject: North side of Chicago Link
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Is there a need for a link on the north sude of chicago near the Devon & Western area?
I am interested in getting setup in packet (again) and would like suggestions on TNCs. My old one is now usable.
Thanks' |
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ka9vnv Site Admin
Joined: 08 Jun 2004 Posts: 152 Location: Woodstock, IL
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Posted: Mon Nov 29, 2004 11:47 am Post subject:
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Sonny, I was hoping someone more active than I could answer your question, but I think they're all still suffering from excessive turkey ingestion...
Anyway, looking at the map, a fill-in "relay only" digipeater at Devon and Western would help a lot. General coverage is provided by the downtown WIDEn digipeater, but it can't always hear mobiles around the fringes.
When chosing a new TNC, if it is JUST for digipeater duty, get a TNC-2 clone, like the MFJ 1270 series, because you can put the UIDIGI eprom into it (link on http://dididahdahdidit.com if you haven't been there yet) and get the best feature mix for APRS. If you're planning on doing general base operations, then the KPC-3 Plus is the TNC to get. |
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AB9FX
Joined: 31 Jul 2004 Posts: 23 Location: Chicago, IL
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Posted: Mon Nov 29, 2004 3:55 pm Post subject:
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I also would say yes for this location with regular antenna height. I'm located 5.5 miles from this point and experienced 5W from mobile was not enough. I run relay at my home station Devon & Oak Park. |
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KA9FLX
Joined: 13 Aug 2005 Posts: 13 Location: Palos Hills, IL
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Posted: Sun Jan 13, 2008 12:13 pm Post subject: More Digis are not necessarily a good thing!
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Ok, really chiming in late here and hopefully this is not a stupid response.
Generally speaking a 5 watt mobile should get into the network from just about any location in the Chicago area.
Having said that, there are some things to consider....
1.) first and foremost, additional digipeaters are NOT neccesarily a good thing! Keep the protocol in mind and one quickly realizes that at some point the additional stations are just adding to the problem.
Rather than a digipeater, why not consider a RX only I-Gate such as what I we did here in the SW Burbs (Palos Area) to fill a hole for our trackers. That way weak stations and/or those in a RX coverage hole from the main sites are still heard and placed onto the internet, where their positions are relayed over both the internet and eventually the main sites/digis.
In the case of the Palos area, our trackers can hear the big wide coverage digis just fine 99% of the time. Unfortunately, because of the terrain and our trackers being 1-5W radios, we don't always get heard by the WIDE2-n, or for that matter the WIDE1-1.
So, to fillthe hole without adding to the congestion, we have several sites that are RX only, but gate RX traffic to the interent. No digi, no internet to RF gating. Problem solved!
I'm not saying don't put up a digi, only that transmitting is not always necessary.
2.) It may be that the area in question has a lot of interference. Sadly many a traffic light controller is known for RFI at moderate range. So, it may be your mobile is simply not hearing a digi. In the case of trackers, this is not realy a problem since there is no need to actually receive and ACK. On the other hand, if you are trying to receiver WX or TXT messages, it could be.
Bottom line, the best course of action is to find out what is causing the coverage hole in the first place and then decise on a course of action.
73,
Bob - KA9FLX |
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Robbie
Joined: 02 Jul 2004 Posts: 32 Location: Buffalo Grove, IL
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Posted: Mon Jan 14, 2008 6:40 pm Post subject: I-Gate only?
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Bob, KA9FLX,
I don't understand your reasoning about RX only base stations Bob.. Anytime mobiles passing thru an area that can't hit a WIDEn-N digi, I would think a home station WIDE1-1, (relay), would be desireable to aid them reach a wide digipeater. Why only to the internet? There are many APRSers that do not hook up to the internet. Those users will never see the stations that I-net only stations sees, so their whereabouts will not be seen. Their services or capabilities would not be known, specially if the internet was down.
Ah, I may have found part of your reasoning Bob, you don't use the RF network from what I can see on Findu, just the APRS-IS. You can see all your 5 watt or less friends. I would strongly suggest reconsidering a Fill-in type of digipeater for RF if there is in fact a hole for the big WIDEn-N in your area.
73, Robbie Signed Robbie, wa9inf |
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KA9FLX
Joined: 13 Aug 2005 Posts: 13 Location: Palos Hills, IL
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Posted: Mon Jan 14, 2008 8:17 pm Post subject: fill digis
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Robbie,
Actually, all traffic picked up by my RX only gate and placed on the internet, does find its way back onto the RF through the primary I-Gates that backfeed the internet onto the RF.
Many, if not most trackers don't even use their receivers except to detect channel activity, so there is no need for a fill digi because all that traffic does as I said, finds it way onto the APRS network. I've run RF only (No internet) and I've not missed any stations.
As to why I think transmitting is not always good, again the more (TX) traffic there is out there, the more the system is conjested. A fill transmitting "fill" digi that is retransmitting packets that are also being heard by a WIDE2-n is potentially keeping people from getting messages.
The one weakness of AX.25 is that it has limited capacity. This was sort of the whole idea behind APRS in the first place. The WIDEn-n format, along with digi code was created to minimize, if not eliminate the number of times a packet got bounced between sources.
However, while in the example above the packet would eventually get killed once the WIDE2-n station rebroadacast it (changing the header), the initial dual transmission by the WIDE1-1 digi is basically a waste of air time and again, could have possibly caused a nearby receiving station to miss the packet altogether.
Again, I'm not against fill digis at all. Just saying that a coverage hole can be caused by a lot of things and simply setting up a digi in the hole is not always the correct course of action.
73,
Bob - KA9FLX |
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