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

[James Washer]

On Thu, 27 Jan 2005 22:19:25 -0800 (PST)
Curt Mills <archer at eskimo.com> wrote:


> The dupe queue is one of the nicest things about the
> WIDEn-N/TRACEn-N system.  Consider implementing that if you have
> enough RAM in your microcontroller.  Just saving a CRC-16 for each
> heard one, for 30 seconds or so, might be enough.  You wouldn't have
> to save each packet for 30 seconds.
> 
> If you don't mind my asking, what uP are you using?
> 
> -- 
> Curt, WE7U.				archer at eskimo dot com
> http://www.eskimo.com/~archer
>   Lotto:  A tax on people who are bad at math. - unknown
> Windows:  Microsoft's tax on computer illiterates. - WE7U.
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I'm using an AVR along with an MX614

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?

 - jim

p.s. That's for the answers on the H-bit vs WIDEn-N.