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

Scott Miller scott at opentrac.org
Thu Sep 20 20:16:14 UTC 2007


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
>>
> 
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> 





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