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[aprssig] an off-topic query about statistical analysis in digital modes

Steve Noskowicz noskosteve at yahoo.com
Fri Sep 21 01:29:52 UTC 2007



Perhaps you know that PSK31 has variable length
symbols with more common ones (letters e, t, a, o, i,
n, s))  having shorter codes.

73, Steve, K9DCI


--- Scott Miller <scott at opentrac.org> wrote:

> http://www.tapr.org/pub_wdcdat.html
> 
> Wireless Digital Communications: Design and Theory,
> by Tom McDermott, N5EG.
> 
> I'm sure there are plenty of other good texts out
> there, but this one 
> covers a lot of ground that's of particular interest
> to hams.
> 
> Also see the Wikipedia articles for convolutional
> code, viterbi decoder, 
>   and Hamming distance.  They have some good
> information and plenty of 
> references.
> 
> Scott
> N1VG
> 
> w0ep at frii.com wrote:
> > 
> > Is there a good book to learn about these things?
> > 
> > 
> > On Thu, 20 Sep 2007, Scott Miller wrote:
> > 
> >> I think what you're describing is basically a
> convolutional code.
> >>
> >> Such things work better when you've got
> side-channel information to work
> >> from - like if you know one particular bit was
> closer to the decision
> >> threshold than the others, you know that one's
> the most likely to be wrong.
> >>
> >> In APRS you might be able to recover more data by
> knowing that certain
> >> fields are always digits, or always alphanumeric,
> and using that
> >> knowledge to try flipping specific bits to see if
> the new message
> >> matches the checksum.
> >>
> >> Of course, you're still better off encoding it
> with a proper
> >> convolutional code in the first place...
> >>
> >> Scott
> >> N1VG
> >>
> >> w0ep at frii.com wrote:
> >>> We've kind of been on an off-topic swing and
> >>> I know this is a good place to find people that
> know
> >>> about digital data transmission so:
> >>>
> >>> Are there any digital data transmission systems
> that
> >>> use a dictionary of expected terms and
> statistical
> >>> analysis that assigns probability to incoming
> >>> raw data to match against the dictionary?
> >>>
> >>> Sort of like what my BlackBerry does with
> SureType mode?
> >>>
> >>>
> >>>
> >>> _______________________________________________
> >>> aprssig mailing list
> >>> aprssig at lists.tapr.org
> >>>
>
https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig
> >>>
> >>>
> >>
> >> _______________________________________________
> >> aprssig mailing list
> >> aprssig at lists.tapr.org
> >>
>
https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig
> >>
> > 
> > _______________________________________________
> > aprssig mailing list
> > aprssig at lists.tapr.org
> >
>
https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig
> > 
> > 
> 
> 
> _______________________________________________
> aprssig mailing list
> aprssig at lists.tapr.org
>
https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig
> 



       
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