It also needs to be kept in mind that with rounding taking place at the
sending Skimmer's Telnet server, an actual calibration difference of
only a couple of Hz can lead to spots being 0.1 KHz apart. This isn't
just a Skimmer issue - in fact, any spotting mechanism that readsthe
receiver's frequency can be off by even more - for example, I use a 400
Hz filter to run, and frequently tweak my main tuning control to get out
from under a packet pileup. Any spot I then make can easily be 0.2 KHz
or more different from others' spots of the same station.
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 2/25/2013 9:54 PM, Jim Jordan wrote:
There are two explanations for reported frequency variations unless
they are reported at EXACTLY the same moment in time--rx error or tx
change. Many run stations, myself included, if that less than perfect
run frequency becomes even less perfect we will adjust the tx
frequency ever so slightly to try and get in the clear. On the next CQ
after that another skimmer may pick up the new frequency and report
that as a new spot or it may be interpreted as the same spot but a
different frequency. Saw that in ARRL DX CW when I shifted frequency
while running at NY4A. Not sayin' one way or the other, but consider
all possibilities.
73,
Jim, K4QPL
----- Original Message ----- From: "Pete Smith N4ZR"
<n4zr@contesting.com>
To: <vr2bg@harts.org.hk>
Cc: <cq-contest@contesting.com>
Sent: Monday, February 25, 2013 9:35 PM
Subject: Re: [CQ-Contest] Summarizing the Skimmer Accuracy Thread
Bret, send me your data in a form I can look at, and we can have a
useful discussion. I can imagine several scenarios for what you
describe - harmonics, dueling CQs, keyclicks, and so on.
I'd love to see your data. Your assertion about 1-2 percent errors
is totally out of the ball park. The RBN made 3.7 million spots
during ARRL CW - are you really saying there were 37,000-74,000
erroneous spots? Show me!
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 2/25/2013 6:33 PM, VR2BrettGraham wrote:
Here is some more data. On 2012-09-21, there were 151 RBN spots of
the same call but on another frequency >3 kc away on the same band
at exactly the same time (to the second) as another skimmer spot.
For this query, I can avoid "dupes", so opening that up to spots of
the same call >3 kc apart on the same band within about 9 seconds of
each other finds 369.
That is just one mechanism. Spots of same call on different band on
the very same second look to have been 140. That's already 0.3% of
RBN spots that day & that will exclude a LOT of wrong-band spots.
Add busted call spots & who-knows-how-many busted call wrong-band or
wrong-freq spots & then scale all this up by some factor as activity
is much higher on weekends (I'm working with weekday data here, as
it makes it easier to find wrong-band spots as no multi-multis on
then) - I believe RBN could be blowing 1-2% of what it spots,
perhaps more.
_______________________________________________
CQ-Contest mailing list
CQ-Contest@contesting.com
http://lists.contesting.com/mailman/listinfo/cq-contest
_______________________________________________
CQ-Contest mailing list
CQ-Contest@contesting.com
http://lists.contesting.com/mailman/listinfo/cq-contest
_______________________________________________
CQ-Contest mailing list
CQ-Contest@contesting.com
http://lists.contesting.com/mailman/listinfo/cq-contest
|