[Skimmertalk] [N1MM] Re: Frequency (volume) of Spots (OT)

[Pete Smith]

Hi Luc - thanks for this.

My hunch would be that perhaps your transmitter is clipping the first 
"dit" just a little - not enough to confuse the human "decoder" but 
enough to throw the machine decoder off.  I had this problem with my 
Winkey until I set 20 milliseconds of lead time to allow my transceiver 
to "get ready" for CW.

The 11-year database is a database of patterns, not of callsigns per se 
- GW7T would certainly be seen as a legitimate call.  Skimmer Server 
does not permit use of the Paranoid validation level, so there is no 
comparison with master.dta being performed.

73, Pete N4ZR

The World Contest Station Database, updated daily at www.conteststations.com
The Reverse Beacon Network at http://reversebeacon.net, blog at reversebeacon.blogspot.com,
spots at telnet.reversebeacon.net, port 7000


On 12/3/2010 6:17 AM, Luc PY8AZT wrote:
> 2010/12/3 Pete Smith<n4zr at contesting.com>
>> Hi Joe - the process for identification of who is CQing is a little more
>> sophisticated than that. First, Skimmer identifies what it considers
>> signals on a given band and assigns a decoder to each one. Then the
>> decoder starts reading the text being sent, looking for such key words
>> as TEST, CQ, QRZ, QRZ?, and SS. If it finds a key word, it looks for a
>> callsign within 256 characters after the keyword. If it finds one, then
>> it looks for that call to be repeated a number of times set by the level
>> of callsign validation that the owner has specified. It also compares
>> the callsign with a table of callsign formats derived from 11 years of
>> cluster spots, again with varying stringency depending on the level of
>> validation. If it passes all of these tests, then the callsign is spotted.
>>
>> Result is that it is pretty clever at finding people calling CQ. The
>> only case that causes it real problems is when the contest station
>> simply signs his call, without ever using a keyword. That could be one
>> reason why some CQers escape the Skimmer net, and we recommend that to
>> avoid this, stations should add the word TEST every 10 minutes or so.
>>
>> 73, Pete N4ZR
> Pete,
>
> I got your email on N1MMLogger, so I moved the topic to Skimmer maillist.
>
> At PW7T we've been spoted many times as GW7T. So, in consequence we've
> got 290 dupes in the log.
>
> Reading your message, I didn't get how we were so badly spoted so many times.
> It's suppose to be:
> 1) Our TX had some problem in CW - so human brain fix it and called us
> correctly - I don't think so... but... It can happens
> 2) The GW7T exist in this spot database (even as wrong spot)
> 3) Skimmer had some problem to listen to the very first dot, we were
> calling "PW7T PW7T Test"
>
>
> --
> 73, Luc
> __
> PW7T Team member
> WRTC.2010 Brazilian Team Leader
> PY8AZT (also PT7AG, PX8C, ZZ8Z, ZY7C)
> LABRE, ARRL, CWJF&  Fortaleza DX Group Member
> __
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