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Re: [aprsisce] a couple of questions

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  • Lynn W Deffenbaugh (Mr)
    ... I ll ditto that conclusion. The overall recommendation is WIDE1-1,WIDE2-1 for mobiles boosting to WIDE1-1,WIDE2-2 if you know you ll be traveling in the
    Message 1 of 9 , Feb 8, 2013
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    On 2/8/2013 9:11 AM, Randy Love wrote:

    On Thu, Feb 7, 2013 at 7:30 PM, <kc8sfq@...> wrote:
    Well, yes, thank you. It IS clearer than it was. I'll make that change before tomorrow morning's drive. Do I need to go back into the config menu and change it to request more hops when I go outside our well covered local area.

    Generally, if you leave it at WIDE1-1,WIDE2-1, you are fine, as long as you have reasonable beaconing rates. That is the path we recommend in the southern half of Michigan. When you go "Up North" or out of state outside metro areas, WIDE1-1,WIDE2-2 is perfectly fine.

    I'll ditto that conclusion.  The overall recommendation is WIDE1-1,WIDE2-1 for mobiles boosting to WIDE1-1,WIDE2-2 if you know you'll be traveling in the APRS boondocks.  I believe the Los Angeles (or is it San Fransciso) area have configured their digipeaters to "trap" this path and truncate it to something more in keeping with their dense APRS RF environment.

    You can check out my APRS coverage maps at the following URLs if you're interested in seeing the activity levels for an upcoming road trip:

    (Note that CoralCDN seems to be having issues for some people, so you may need to remove the ".nyud.net" from those tinyurl expansions)

    It is perfectly normal in good coverage areas to hear your WIDE1-1,WIDE2-1 packet being digipeated multiple times, especially if you can hear the CHLSEA and HOLAND digipeaters in addition to the more local N8TJG-10 digi.  Consider the following 3 copies of one of your commute packets this morning (from my raw RF feed from APRSISCE/32 IGates, times in Eastern):

    2013-02-08 07:09:19 KC8SFQ-9>APWW10,N8TJG-10*,WIDE1*,CHLSEA*,WIDE2*,qAR,KB8RCO:@120915h4228.26N/08517.33Wp087/009/A=000980(Proj 101%)APRSIS32 for windows
    2013-02-08 07:09:19 KC8SFQ-9>APWW10,N8TJG-10*,WIDE1*,CHLSEA*,WIDE2*,qAR,W8FSM-3:@120915h4228.26N/08517.33Wp087/009/A=000980(Proj 101%)APRSIS32 for windows
    2013-02-08 07:09:19 KC8SFQ-9>APWW10,N8TJG-10*,WIDE1*,HOLAND*,WIDE2*,qAR,N8CTT:@120915h4228.26N/08517.33Wp087/009/A=000980(Proj 101%)APRSIS32 for windows

    According to aprs.fi, this packet was gated by W8DF-5 (running UI-View, so I don't get RF feeds from it) who heard it direct (time is UTC):

    2013-02-08 12:09:17 UTC: KC8SFQ-9>APWW10,WIDE1-1,WIDE2-1,qAR,W8DF-5:@120915h4228.26N/08517.33Wp087/009/A=000980(Proj 101%)APRSIS32 for windows

    From the first three packets, we know that N8TJG-10 digipeated your packet from the WIDE1-1.  You probably heard that packet come back to you.  Further, both CHLSEA and HOLAND heard N8TJG-10's digipeat and digipeated it again from the WIDE2-1.  If you are in earshot of those high coverage digipeaters, you'd have heard one or both of them, depending on their individual carrier detect delays (the FM capture effect and packet fratricide only works if the digipeaters both heard silence when they wanted to digipeat, otherwise their packets may be sequential instead of concurrent).  So, from that single transmission, you may have heard (at least) 3 digipeats.  If there are other digipeaters that were not heard by APRSISCE/32 IGates, you may have heard them as well, but my raw RF logs wouldn't show those packets to exist.

    Assuming a relatively close synchronization of timestamps (a fairly rash assumption), we can also see the time delay for 2 digipeats.  Your station generated the packet at 12:09:15.  The direct reception was logged by aprs.fi at 12:09:17.  The three double-hop receptions were logged by my server at 07:09:19 (UTC-5).  Yep, RF propagation and digipeating isn't instantaneous!

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

    PS.  Thanks to KC8RCO, W8FSM-3, and N8CTT for running APRSISCE/32 IGates and contributing to this analysis.

    PPS.  I've attached a text file with your packets captured from my RF feed from your commute this morning.

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