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22870Strange path for repeater object.

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  • Tony VE6MVP
    May 10 2:20 PM
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      At 07:20 AM 2013-05-10, Robert Bruninga wrote:

      (I'm not on the APRSSIG TAPR mailing list but I'm awaiting moderation.   I had a long posting on the APRS mailing list with a subject of Repeater objects via WIDE2-1? on the 24th of February on this topic however I only received one answer.  I also decided to change the subject of this posting.)

      I figured mentioning that path for that particular object would be "interesting."  <smile>  These digis mentioned in that have been setup by very competent operators.   I just turned my igate back on so you can, possibly, get a better feel for what I'm doing rather than looking in older history.   http://aprs.fi/info/a/VA6OO

      Background

      My mobile Nuvi 350 attached to an OpenTracker2 displays the packets it hears from the digis including my own packets.   As a result of watching the display being updated over the last year as I drive around and reviewing APRS.FI after a trip I've come to the conclusion that while the digi's can hear my packets for about 50 or 60 kms I can only reliably hear those packets for about 25-35 kms.  

      Given that the object is only transmitted every ten minutes the traveller might be within 10 kms of the repeater before they see the object, such as a repeater, on their screen.  They could've been working that repeater for another 40 or 60 kms away if they had seen the repeater object sooner.

      Therefore, in my opinion, some objects such as repeater objects, should be one hop digipeated by the various digipeaters around the object.  So the traveller has the object in their device memory and on their screen not too long before they enter that repeater object range.    But they are still well out of range of hearing the object on the digi.

      Details

      You can best see this area I reside in by http://aprs.fi/#!addr=edgerton%2C%20ab and zooming out and repositioning the screen so you can see the VA6OO and VE6CIC igates as well as the ALIANC and PROVST digipeaters.

      The path VERMLN,LLOYD,PROVST,ALIANC is for repeater object 145.29-RW

      Now for this particular repeater,   http://aprs.fi/info/a/145.29-RW , I am to the north and east of it.   I can't reliably hear all four digipeaters.   The first digi on the list is my closest digi and to the north of that repeater.   The second digi is to the NE of that repeater which I can reliably hit but it's main purpose in the list is to get my repeater object packet to the third and fourth repeaters. The third digi on the list is to the east of that repeater while the fourth digi on the list is on the west of that repeater.   So basically the packets are travelling in a ring or box   around the repeater.

      By not using a WIDE2-1 or WIDE2-2 I don't "leak" the repeater object info to the north or west of me to adjacent digis which would be way out of range of the repeater.

      Misc

      Also we have a very lightly loaded network out here so we can experiment a little without causing congestion in the nearby city which is three hops away.

      I think I know which station you mean is generating 26 objects.   I think he is currently only generating a number of repeater objects and about two or three of other objects on a regular basis and I somewhat disagree with one or two of them but I can see his point on those as well in an ARES situation.

      That said it was very nice that the one repeater 145.250-R  was digiipeated with a path of some sort.  I was travelling into Stettler and had forgotten to record that local linked repeater frequency ahead of time.  I was mentally kicking myself when I looked over at my Nuvi 350 and there was the object.  So I entered the frequency on my radio and was happily chatting with someone.

      Finally we only have two APRS igates in my rural two hop area.  I'm running mine, VA6OO, most of the time but do play around with satellite once in a while.  So it would probably be better for the other igate operator, who is closer to that repeater, to create this particular repeater object.   But I feel that his path should be the same as mine, so that adjacent digis will see that particular repeater object. 

      Tony VA6OO

      > I have one repeater object where I specify the four digipeaters
      > path to ensure the APRS object covers the area of the voice
      > repeater but no where else.  If you care the path is
      VERMLN,LLOYD,PROVST,ALIANC)

      I'm sorry to jump in here with lead feet, (and am not following the
      thread) but on the face of it, I fear that path violates the most
      fundamental principles of the LOCAL INFO and FREQ objects:
      http://aprs.org/localinfo.html

      1) The object is not sourced *at* the digis, but *via* the digis
      2) This source cannot hear what the digis hear, and so it has a higher
      probability of collision with all other area packet sources.
      3) Only the digis are supposed to source these objects and only
      *direct*since they will ONLY TX when the channel is clear and *only* the
      digis know when the channel is clear.
      4) Digipeating normally doubles the channel loading for this kind of info
      5) But in this case Digipeating via 4 hops *quintuples* the channel
      loading for bjects which are supposed to be invisible to user load.
      6) Two of those digis do not show PHG data so it is impossible to analyze
      the network from the maps

      Zooming into the area I see some other frightening situations with one
      station originating at least 26 such objects!*!

      Now, no one likes advice from afar, But -if- all these objects are being
      transmitted as recommended at 10 minute intervals (the value to mobiles
      driving into the area) then that local network would be nearly saturated
      with nothing but these objects with no room for anything else.

      I cannot see the paths used for these objects, because the APRS-IS strips
      the path when heard by an IGate, but if they are anything other than
      *direct* and if they are sourced anywhere other than at the digi's
      themselves, then they are not properly implemented in accordance with the
      design of Frequency (repeater) objects.

      On the other hand, I value these kinds of objects very highly, and if
      abusing the network is the only way to work around lethargig DIGI
      operators, then so be it. But it is not the right way to do things. And
      certainly 4 hops is the worst thing. If the network must be so abused
      because the digi operators will not set up their digis to serve travelers,
      then at least originate the object Central to the 4 digis so that only a
      *single* time slot can hit all 4 digis at once.

      Again, I could very well be taking things all wrong. So in that case just
      ignore me and consider this a sermon to the choir...

      Bob, WB4aPR
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