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

AE5PL Lists HamLists at ametx.com
Mon Sep 27 18:44:55 UTC 2004


> -----Original Message-----
> From: Wes Johnston
> Posted At: Monday, September 27, 2004 10:45 AM
> Subject: RE: [aprssig] APRS low-power-local ALT input channel
> 
> And finally, if CSMA works so well, why did they switch to 
> DAMA in europe?

Never said it works well.  Just said it is better than pure ALOHA.  And,
it is what we are stuck with in the current ad hoc distribution of APRS
as there is no central control of the APRS frequency on two meters (at
least in the US) which is what is required for DAMA to really work well.

By the way, regarding a comment you made earlier in your post, if two
D700's are using the 144.99/144.39 approach with CD on 144.39, you have
increased your chance of collisions markedly in a heavy use area because
they both will go for the same 2 second dead spot and neither will have
the benefit of recognizing that the other has started transmitting.
There will always be some small variances in the timing between rigs
which could be made use of in a simplex operation, but not in this mode.

73,

Pete Loveall AE5PL
mailto:pete at ae5pl.net 




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