[Skimmertalk] Skimmer Tests during SS

David Robbins K1TTT k1ttt at arrl.net
Sat Nov 15 15:58:09 EST 2008


If a station called just after a cq ended, then sent his call in the
exchange, I'm thinking that seeing the cq, the callsign, then the same call
again shortly after that, even if interleaved with the real cqing station.


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: Saturday, November 15, 2008 20:43
> To: skimmertalk at contesting.com
> Subject: Re: [Skimmertalk] Skimmer Tests during SS
> 
> Could be, but normally it needs to actually see a "tag" with the callsign
> like CQ or Test.  Conceivably, "with" is defined by a period of time, so
> if
> the stations were closely enough zeroed that could happen.  I will ask
> Alex. and will do some experimenting during CQWW CW.
> 
> 73, Pete
> 
> At 03:08 PM 11/15/2008, David Robbins K1TTT wrote:
> >I am wondering... in ss it is relatively unique that you send your call
> as
> >part of the exchange.  I wonder if skimmer was accidentally picking up on
> >stations calling the one who was cqing?
> >
> >
> >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: Dick Green WC1M [mailto:wc1m at msn.com]
> > > Sent: Saturday, November 15, 2008 19:42
> > > To: 'Pete Smith'; skimmertalk at contesting.com
> > > Subject: Re: [Skimmertalk] Skimmer Tests during SS
> > >
> > > Jim and I have been discussing his report offline. His results don't
> > > correlate with mine in IARU CW, where I often got more spots for CQing
> > > stations than I could keep up with, and accuracy was outstanding.
> > >
> > > While Pete is probably correct about the effect of SO2R time delays on
> > > finding CQing stations, another reason for the low hit rate is that
> it's
> > > quite common for stations CQing in SS to simply send something like
> "SS
> > > <call sign> <call sign> SS". The words "CQ" and "TEST" are often
> omitted.
> > > CW
> > > Skimmer doesn't have SS-specific code, does it? If not, I'm sure it
> will
> > > eventually... :-)
> > >
> > > I agree on using Paranoid mode. With the right SCP file, that would
> have
> > > eliminated the non-USA calls, and I suspect it would have greatly
> reduced
> > > the number of busted calls that got mangled into valid FCC calls.
> > >
> > > 73, Dick WC1M
> > >
> > > > -----Original Message-----
> > > > From: Pete Smith [mailto:n4zr at contesting.com]
> > > > Sent: Saturday, November 15, 2008 6:44 AM
> > > > To: skimmertalk at contesting.com
> > > > Subject: Re: [Skimmertalk] Skimmer Tests during SS
> > > >
> > > > I have posted the full report at
> > > > http://www.pvrc.org/~n4zr/K5QQ%20Skimmer%20Test%20-%202008%20SS.pdf
> > > >
> > > > His statistics are very interesting.  However, I'm a little
> skeptical
> > > > about
> > > > Jim's conclusion that I quoted below.  In my tests, if anything,
> > > > Skimmer
> > > > does not identify *enough* of the stations that are running.  It
> > > > relies on
> > > > markers in the stations' transmissions, such as QRZ, TEST,or CQ.  If
> a
> > > > station is running on a frequency, just signing [call] TU or[call]
> UP,
> > > > then
> > > > Skimmer doesn't know that he is "CQ-ing."
> > > >
> > > > I suspect that part of the problem Jim encountered is due to SO2R
> > > > stations
> > > > CQing, and then taking a pretty long time to work someone they find
> on
> > > > the
> > > > second radio.  The issue with busted calls is real, of course, and
> > > > many of
> > > > them are going to be legitimate calls, because even in Aggressive
> mode
> > > > Skimmer is relying on patterns rather than a positive list.  If you
> > > > want to
> > > > cut way down on the number of busted calls, switch to Paranoid, and
> > > > make
> > > > sure Skimmer is pointed to a current master.dta file.
> > > >
> > > > 73, Pete
> > > >
> > > >    At 05:36 PM 11/14/2008, Jim Baremore wrote:
> > > > >I performed this evaluation at 8 different intervals during the
> > > > contest and
> > > > >did evaluations on 20, 40 and 80.  All total 359 spots were tested.
> > > > Of
> > > > >those, only 111 were the station CW Skimmer was indicated on the
> > > > frequency.
> > > > >30 were for a station whose callsign was close but which I judged
> > > > Skimmer
> > > > >had missed a dit or something and mangled it into another call.
> > > > >Interestingly enough, the mangled call was still a valid FCC call.
> > > > Finally,
> > > > >218 spots were for stations no longer on the frequency.  Most
> likely
> > > > they
> > > > >were stations just worked by the station running the frequency.
> > > >
> > >
> > >
> > > _______________________________________________
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> > > Skimmertalk at contesting.com
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> >
> >
> >
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