[Skimmertalk] Bad Skimmer Spots

[K1TTT]

That is why arc-6 is passing all the rbn spots on to the client, so duping
and filtering can be done by the user.  You might also want to check out
some of the new filters, in the latest beta update there is a number of
times spotted filter, so you can limit the rbn spots you see to ones that
have been spotted 2 or more times, and there is also a master.dta filter to
only see spots in the supercheck database... Those filters can be combined
in statements like:

not skimmer or (skimmer and unique > 2) or (skimmer and master)

Which would give you all non-skimmer spots, plus skimmer spots that are
spotted more than twice on the same band within 10 minutes, plus skimmer
spots that are in the master.dta file regardless of how many times they are
spotted.


David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://www.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
 

> -----Original Message-----
> From: Pete Smith [mailto:n4zr at contesting.com] 
> Sent: Friday, February 04, 2011 13:38
> To: Igor Sokolov
> Cc: Skimmertalk at contesting.com
> Subject: Re: [Skimmertalk] Bad Skimmer Spots
> 
> 
> There is a third possibility, but the problem is a little 
> trickier than 
> I had thought.  Here's an excerpt I just sent to someone on 
> another list:
> 
> "As for the theoretical error rate, let's take an example.  
> Say you have 
> N6NC CQing for an hour and being heard by 10 RBN Skimmers.  
> Each Skimmer 
> will spot you correctly 5-6 times (every 10-12 minutes).  But if some 
> local event - transmitter splatter, QRN, QRM (especially things like 
> clicks from a loud adjacent station) causes a mis-spot, then 
> whichever 
> Skimmer that mis-spotted you will immediately send out a bad spot.
> 
> Say just one of the Skimmers listening to you sends one bad 
> spot of you 
> in that hour. That's 1 bad spot.  Meanwhile, the good spots are being 
> filtered out as dupes by client software, so that clients are only 
> receiving 5-6 good spots of you.  Holy cow, that's a 16-20 percent 
> apparent error rate.
> 
> It's the aggregation, which is why the RBN has to come up with a 
> solution.  This is a fairly tricky problem, because the system has a 
> built-in preference for new spots, whether good or bad.  The 
> bad spots 
> can come at any time when you are CQing.  Meanwhile, the good 
> spots will 
> tend to cluster, because most people who spotted you 
> correctly will have 
> done so within a few seconds of your first CQ, and then at 
> 10-12 minute 
> intervals thereafter.  I don't know just how this one will be solved, 
> but I think it can be.  The devil, as usual...
> 
> 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 2/3/2011 11:38 PM, Igor Sokolov wrote:
> > Lee, I think it would be excellent if VE7CC client software 
> could have
> > filtering and validation facilities. There were so many 
> broken spots during
> > CQWW 160 that filled the entire band map and their 
> percentage was reaching
> > 80% on the last night of the contest.
> > I see two methods of validating spots:
> >   1) pass the spot if the call has been mentioned by 2 or 3 
> other skimmers
> > 2) Pass the spot if it is in the master. dat file.
> > Combination of these two would probably cut the number of 
> broken spots to
> > acceptable figures.
> > I think telnet client software is the best place for 
> filtering (better then
> > filter in the logger or at the skimmer)
> >
> > 73, Igor UA9CDC
> > ----- Original Message -----
> > From: "Lee Sawkins"<ve7cc at shaw.ca>
> > To:<Skimmertalk at contesting.com>
> > Sent: Friday, February 04, 2011 3:12 AM
> > Subject: [Skimmertalk] Bad Skimmer Spots
> >
> >
> >> Here is a small subset of bad skimmer spots. I am looking 
> at a full feed
> >> from the RBN.
> >>
> >> These are only spots for USA calls that have not been 
> issued.  Many times
> >> the first letter of a call is missing.  Many of these are 
> actually Italian
> >> calls with the "I" missing.
> >>
> >> http://www.bcdxc.org/ve7cc/notissue.txt
> >>
> >> I will update the list from time to time.
> >>
> >> CC Clusters drop these bad calls.
> >>
> >> There are many other non USA calls that are wrong which 
> also have the
> >> first
> >> letter missing. These are harder to find.
> >>
> >> Other bad calls occur when the last letter is missing or 
> truncated or is
> >> added
> >> +in error.
> >>
> >> "E" and "T" seem to be the most often added bad letters.
> >>
> >> Lee
> >> _______________________________________________
> >> Skimmertalk mailing list
> >> Skimmertalk at contesting.com
> >> http://dayton.contesting.com/mailman/listinfo/skimmertalk
> > _______________________________________________
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> >
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