[aprssig] Question about 'H-bit' handling and WIDEn-N paths

[James Washer]

You bet I'm using GCC.. What a great environment to work with.. Zero cost dev environment, near zero cost programmers, and who can complains about things like the STK500 or the Butterfly!

 - jim

On Fri, 28 Jan 2005 08:36:27 -0800 (PST)
"Curt, WE7U" <archer at eskimo.com> wrote:

> On Fri, 28 Jan 2005, James Washer wrote:
> 
> > I'm using an AVR along with an MX614
> 
> Yea!  Another AVR users.  Perhaps we should compare notes...  Using
> GCC for your compiler?
> 
> 
> > Ok.. you bring up another interesting question. You say that by
> > keeping a history of 30seconds worth of CRC's we can avoid sending
> > dupes, but setting the H-bit OR decrementing WIDEn-N/TRACEn-N will
> > change the CRC. So what are they doing? Calculating a special CRC
> > on the payload or something?
> 
> Whatever method you wish.  If it were me I'd think about computing a
> CRC-16 on just the INFO field of the packet, and keeping it for 30
> seconds.  That way any changes to the header fields wouldn't affect
> the dupe-checking at all.  No user or digi would be able to
> circumvent the dupe-checking.
> 
> --
> Curt, WE7U.   APRS Client Comparisons: http://www.eskimo.com/~archer
> "Lotto:    A tax on people who are bad at math." -- unknown
> "Windows:  Microsoft's tax on computer illiterates." -- WE7U
> "The world DOES revolve around me:  I picked the coordinate system!"
> 
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