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[aprssig] APRS low-power-local ALT input channel

AE5PL Lists HamLists at ametx.com
Sat Sep 25 11:30:51 UTC 2004


No.  Bob is again trying to justify the elimination of any type of
collision avoidance based on the faulty premise that if it is not 100%
effective, then don't do it.  Ground level users are in a combination
aloha/CSMA network.  In fact, in a local operation (which is what we are
talking about), ground based devices do see a high percentage of other
transmitted packets (the need here is not to be able to decode those
packets, but to see the signals).  I stand by my statement: it is bad
operating practice to transmit without listening first to prevent
intentional interference on a shared channel.  It is bad data network
design to use a shared channel with no attempt to have a collision
avoidance method.

73,

Pete Loveall AE5PL
mailto:pete at ae5pl.net  

> -----Original Message-----
> From: Bill Herrmann
> Posted At: Saturday, September 25, 2004 3:07 AM
> Subject: RE: [aprssig] APRS low-power-local ALT input channel
> 
> At 11:50 PM 9/24/2004 -0400, Robert Bruninga wrote:
> >Ah, that is a common missunderstanding.
> >When any system uses HIGH site repeaters to serve many ground
> 
> While it's true that the ground level users are in an aloha 
> network it isn't true that the high site repeaters are. They 
> are truly in a CSMA network. I think what Pete was getting at 
> is that we need to be building those high site cross-channel 
> digipeaters so that they check for busy before they transfer 
> the packets from the alternate network to the main
> 144.39 network.
> 
> Pete - Is that where you were going?




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