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[aprssig] Local Event using RELAY?

AE5PL Lists HamLists at ametx.com
Mon Mar 28 17:44:46 UTC 2005


Bob,

Your extensive attempt at justifying blind transmissions just add
support to Robbie's statement that blind transmission is just not right,
under any circumstances.  Your idea of common sense is sometimes very
contrary to proper operating practices.

The question of operating on two different frequencies at the same time
as you describe it begs the question "Why?", if what you say about
carrier sense by the digipeater is true (that it won't hear anything
other than the distant digipeater anyway).  If that is the case, why not
have everyone operate responsibly on 144.39 if that is where you want
them?  They might hear that far away digipeater too and delay
transmission (a good thing).  Otherwise, their performance in the
scenario you painted would not be affected.  And if the only thing the
mobile digipeater is hearing is the other digipeater, one would question
whether it would provide any benefit to the "local" operations since it
probably would have trouble hearing those, too.

There is a way to operate on two frequencies AND operate responsibly.
That is to have an IGate on the alternate frequency and have an IGate on
144.39 gate anything the other IGate hears to 144.39.  javAPRSIGate
supports this and then transmissions by all involved are using CSMA and
minimizing unwanted interference.  Does it eliminate interference?  NO,
but it certainly causes significantly less interference than what you
propose.  And oh yes, javAPRSIGate does support no-source-route
digipeating which is ideal for special event operations.

73,

Pete Loveall AE5PL
mailto:pete at ae5pl.net 

> -----Original Message-----
> From: Robert Bruninga
> Posted At: Monday, March 28, 2005 11:17 AM
> Subject: Re: [aprssig] Local Event using RELAY?
> 
> >>> mwrobertson at comcast.net 3/28/05 11:47:58 AM >>>
> >That then makes the [mobile event digi] transmit on 144.390 without 
> >listening first and thus qrm'ing anything else on 144.390. 
> That is not 
> >the right way to operate period.
> 
> Too many angeles on that pin, I am sorry to say...
> You are not looking at the big picture and not seeing the 
> forest for the trees.  Its just common sense.




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