[aprssig] Re: [ui-view] RE: APRS low-power-local ALT input channel>>144.34 ?
Robert Bruninga bruninga at usna.eduSat Sep 25 17:35:01 UTC 2004
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APRS on 144.99 if available for local coordination: I think what many people may not understand about this proposal is how an alt-channel is different than 144.39. On 144.39 in a busy area, each DIGI hears the following: 1) A few packets per minute from a *few* Local users 2) 20 to 40 packets per minute from surrounding DIGIs 3) 40 to 20 seconds of DIGI QRM (distant digis that hold off TX) 4) Lots and LOTS of collisions with no successful throughput On an alt-input channel, however, the listen-only digi hears: 1) A few packets per minute from a *few* local users It doesnt take much to conclude that the *few* local users are better off on the alternate channel, and furthermore, that there is absolutely no difference in their ability to hear each other for collision avoidance on one or the other. That is only a function of their geometry, NOT of which channel they are on. It is a WIN-WIN situation all around. This splitting of ALOHA users among multiple input channels has been the primary improvement mechanism for ANY Aloha network since they were first defined in the 1960's. It is fundamental to ALOHA network design Its time for APRS to consider it... de Wb4APR, Bob
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