[CQ-Contest] Skimmer accuracy...

[Pete Smith N4ZR]

Jack, I think you could, if you're willing, have a very fruitful 
conversation with Alex, VE3NEA.  I know a little bit about the 
techniques he's using to assess the plausibility of a given prefix and 
suffix, but you have "been thereand done that" , and I think it would be 
a great contribution.

73, Pete N4ZR
Check out the Reverse Beacon Network at
http://reversebeacon.net,
blog at reversebeacon.blogspot.com.
For spots, please go to your favorite
ARC V6 or VE7CC DX cluster node.

On 2/19/2013 2:52 PM, Jack Haverty. wrote:
> In the spirit of improving accuracy....a suggestion
>
> In the late 1970s, I was involved in a project to use computers to
> understand Morse code.   Google "haverty understanding Morse code" if
> you're curious.
>
> We struggled with the same kind of inaccuracies that Skimmers are now
> experiencing.   We used many independent techniques to generate plausible
> decodings from what came off the antenna plus lots of ancillary
> information, like dictionaries, and "common sense" like expected
> propagation behavior and current band conditions.
>
> The key technique in making the final decoding very accurate was that each
> module that generated an "opinion" about what was being decoded also
> attached a "confidence" to that opinion.   So, a suggested decoding from an
> S9+30 signal with little QRM/QRN/QSB would have a higher confidence than a
> S2 signal in the middle of a crowd with summer static conditions.   A
> decoder might look at a few seconds of signal and suggest that the sender
> said "E5EEE", but if it was a strong signal it would have a very high
> confidence level and if a weak one very low.
>
> That "confidence" factor enabled other modules further down the line to
> make more intelligent decisions about the most likely decoding.   For
> example, a subsequent "callsign module" might look at the decodings
> suggested by the earlier "dot/dash decoders", and conclude that "E5EEE" was
> not very likely, especially if "E5EEE" had been decoded with low
> confidence.  It would offer its own opinion about what the signal contained
> -- for example that it was just noise.
>
> If the Skimmers could produce spots that contained not only a callsign but
> also a "confidence", consumers further down the line (e.g., contest
> programs displaying spots) could filter those spots based on confidence -
> e.g., only display spots that are high confidence.
>
> Perhaps a spotting network convention like <callsign>.<confidence> -- so
> spots would come out across the spotting network looking like "E5EEE.2" or
> "EK3LR.4", or "K3LR.9" or something similar.    Logging software receiving
> such spots could apply their own heuristics, e.g., by consulting a list of
> known contest callsigns, and decide whether or not to display the spot to
> the operator.
>
> 73,
> /Jack de K3FIV   (not VK3FI as I am sometimes labelled....)
>   On Feb 19, 2013 9:46 AM, "Shane Mattson-->K1ZR" <k1zr at comcast.net>
> wrote:
>
>> I'm starting a new thread for increased visibility to this issue.
>>
>>
>>
>> This is by no means a skimmer bashing post, so please don't go there..
>>
>>
>>
>> I'm just curious if others have observed the following:
>>
>>
>>
>> Just for kicks I performed a RBN spot search for my call and the following
>> spots came up during a period of time that I was QRT.  I did not operate at
>> all on Sunday.
>>
>>
>>
>> de    dx    freq  cq/dx snr   speed time
>>
>> K3LR  K1ZR 28005.3     CW CQ 13 dB 32 wpm      2042z 17 Feb
>>
>> K3LR  K1ZR 14046.6     CW CQ 24 dB 31 wpm      2014z 17 Feb
>>
>> KM3T  K1ZR 14046.6     CW CQ 15 dB 33 wpm      2011z 17 Feb
>>
>> VE2WU K1ZR 14046.6     CW CQ 20 dB 31 wpm      1927z 17 Feb
>>
>> K8ND  K1ZR 21006.9     CW CQ 8 dB  32 wpm      1743z 17 Feb
>>
>> NY3A  K1ZR 28062.4     CW CQ 28 dB 31 wpm      1654z 17 Feb
>>
>> K2DB  K1ZR 7020.5      CW CQ 10 dB 29 wpm      0855z 17 Feb
>>
>> K2DB  K1ZR 7020.4      CW CQ 11 dB 30 wpm      0753z 17 Feb
>>
>> K3LR  K1ZR 3510.3      CW CQ 26 dB 29 wpm      0207z 17 Feb
>>
>>
>>
>> Perhaps the skimmers misinterpreted a like-call sign?  I'm not excited
>> about
>> seeing my call detected and spotted during a period for which I was QRT.
>>   An
>> issue like this emphasizes the importance of double checking the call sign
>> for accuracy before logging a point and shoot qso.
>>
>>
>>
>> Could someone within the RBN domain provide some insight as to how to
>> address an issue like this?
>>
>>
>>
>> -Shane
>>
>>
>>
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