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

Scott Miller scott at opentrac.org
Thu Sep 20 20:04:00 UTC 2007


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?
> 
> 
> 
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> aprssig at lists.tapr.org
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> 
> 





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