[aprssig] Mobile Digi (TEMPn-N)
William McKeehan mckeehan at mckeehan.homeip.netMon Jun 15 18:26:56 UTC 2009
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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: > > > > _______________________________________________ > aprssig mailing list > aprssig at tapr.org > https://www.tapr.org/cgi-bin/mailman/listinfo/aprssig > >
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