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[aprssig] Mobile Digi (TEMPn-N)

William McKeehan mckeehan at mckeehan.homeip.net
Mon Jun 15 18:26:56 UTC 2009


Thank you Stephen! This is exactly the type of response that I was looking for.

Thanks!
-- 
William McKeehan
KI4HDU
http://mckeehan.homeip.net


On Mon, June 15, 2009 1:13 pm, Stephen H. Smith wrote:
> William McKeehan wrote:
>> Why would it be a bad idea for the D700's to run around with WIDE1-1 enabled
>> all of the time?
>>
>>
>
> 1)   You wind up with an unstable, constantly-changing network as
> mobiles move around:
>
> o     Either the fixed digipeaters cover an area adequately, in which
> case extra mobile digis are irrelevant and just add channel congestion .
>        --or--
> o     The fixed infrastructure does have coverage holes, but  users can
> never count on fill-in coverage at given locations since mobiles are
> constantly moving around.
>
>
> 2)   You get massive numbers of unnecessary additional digipeats most of
> the time, resulting in a massive increase in channel loading.  Imagine
> the QRM mess and amount of air time consumed  if 5 or 10 mobiles a few
> miles apart in the afternoon rush hour all try to digipeat each other's
> packets constantly.   Then consider the hundreds of duplicate packets
> hitting the local WIDEs from all those mobile digipeats added to the
> home fill-in digipeats.
>
>
> 3)   For everyday use, mobiles make terrible digis since they:
>
> o     Are lower to the ground than even home WIDE1-1 fill-in digis, and
> lack useful antenna height.
> o     Are usually moving.   The data bit-error rate (which causes RX and
> TX failures) due to mobile flutter goes up rapidly as the speed increases.
>
>
> BOTTOM LINE:  Unless a mobile is PARKED and STATIONARY on high ground
> (hill top, top of a parking ramp, etc), they are adding to the problem
> (by creating channel congestion, and possibly adding to the number of
> defective packets) rather than helping.
>
>
> ------------------------------------------------------------------------
>
> --
>
> Stephen H. Smith    wa8lmf (at) aol.com
> EchoLink Node:      WA8LMF  or 14400    [Think bottom of the 2M band]
> Skype:     WA8LMF
> Home Page:          http://wa8lmf.com  --OR--   http://wa8lmf.net
>
> World Digipeater Map
>   http://wa8lmf.net/APRSmaps
>
> JavAPRS Filter Port 14580 Guide
>   http://wa8lmf.net/aprs/JAVaprsFilters.htm
>
> "APRS 101"  Explanation of APRS Path Selection & Digipeating
>   http://wa8lmf.net/DigiPaths
>
> Updated "Rev H" APRS            http://wa8lmf.net/aprs
> Symbols Set for UI-View,
> UIpoint and APRSplus:
>
>
>
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>




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