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[aprssig] FREQUENCY on APRS

Bob Bruninga bruninga at usna.edu
Sun Jan 13 16:59:29 UTC 2008


> Unfortunately beacons from a digi will never 
> contain ALL the area information [of a
> repeater] and will be subject to bias and 
> not rationality.

This missunderstands the function of a Voice Repeater Object.

The Voice Repeater Frequency Object is a FUNCTION of an APRS DIGI.  It is not a function of the voice repeater.  This means it is the local DIGI informing the DIGI's users as to what Voice Repeater Frequency is -recommended- in the -area of this *digi*.

It is *not* an attempt to blanket the area of a voice repeater with beacons announcing the repeater.  There are very important reasons for this disinction to minimize QRM on the APRS channel and to not impact APRS reliability.  These advantages of being at the digi are listed on the "locainfo" web page.  

1) These objects are DIRECT only
   A) limits their area to only where it applies
   B) prevents any QRM to any other area

2) These objects are originated at the DIGI
   A) usually a high location with good coverage
   B) Allows the digi to LISTEN first before TX
   C) eliminates collisions with any users

It is a BAD idea to generate these packets from a home station for ALL of the same reasons!

1) These objects take the 2 or more hops of the home station.
   A) This QRM's thousands of miles of APRS
   B) displays the object where it cannot be used!
   C) is counterproductive to the design of APRS
2) From a home station other users are impacted!
   A) the object will take 2to4 times channel capacity
   B) The object will collide with others at the digi
   C) The user reliabiliy will suffer.

As keith points out.  Generating these objects from home stations is a BAD idea unless it is only temporary until the digi can be properly configured.  Please help everyone to understand this.

READ: http://www.ew.usna.edu/~bruninga/localinfo.html

Bob, Wb4APR




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