Just to add a bit to understanding of how CQ Skimmer and Skimmer Server
work to measure SNR. The SNR for a given spot is measured over a 50 Hz
bandwidth in the moment when Skimmer decides that the spot should be
posted to Telnet. It is true that this value could, conceivably, reflect
a strong signal arriving exactly on frequency within a few milliseconds
after the station finished CQing. But it is also true that some Skimmers
are using low-noise, directional receiving antennas, and since we're
talking SNR, not raw strength, results will vary.
A far more common source of problems, particularly on the low bands, is
that callers can be mistaken for CQers, if they call near enough to zero
beat, send at approximately the same speed as the CQing station, and
send their callsigns at least twice. In that case, it's their own
callsigns that are spotted on the same frequency as the real CQer.
With the current Skimmer architecture, there does not seem to be any way
around this, but the CT1BOH filters implemented in ARCluster V6 can help
a lot. See
<http://64.128.19.154/ArcDocsVer6/UserManual/ArcDx.htm#SetDxFilter> for
details.
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 12/7/2014 8:49 AM, JC wrote:
Hi Thor
Thanks for the heads up I did now that the RBN is so unreliable, and I am very
disappointed with RHR marketing proposal.
EA7PP signal was s7 when most of Europeans just above noise. But you right I
should not accuse people at the first place.
I apologies for my impulse behavior I already apologized to Jose EA7KV.
Regards
JC
N4IS
From: thorvaldur S T E F A N S S O N [mailto:[email protected]]
Sent: Sunday, December 07, 2014 7:25 AM
To: [email protected]
Cc: [email protected]
Subject: Quality of RBN data
Hi JC,
as a proponent of remote technology, which I consider to be of immense benefit
to the Amateur Service, I think we should stick to facts and not let our
emotions concerning new technology cloud our thinking.
Although we will no doubt see cheaters employing remote technology one day, I
think your conclusions about cheating based on RBN data are wrong.
As someone who actually had a RBN receiver at my location for a few years, I
became intimately familiar with the reports from the system.
I had my cluster connection set to show the RBN report for my own transmissions and the
results were sometimes "unbelievable" indeed.
I found that often the RBN would give a fantastic report, yet I knew for a fact
that I might be just above the nose level in that area.
What happens is that the RBN receivers grab the call sign of the DX but a split
second later measure the signal level of the stations calling the DX.
If one of those stations is a local, you see those fantastically strong signal
reports, I think I saw a 70dB report once from the US on 160!
My transmit antenna - the Arctic King - may be powerful, but it´s not that
powerful ;-)
In a contest environment with many strong local stations this problem reaches
monumental proportions rendering the RBN reports in many cases meaningless.
I think we should take those RBN reports with a grain of salt and not submit
unsubstantiated accusations.
73 Thor, TF4M
--------------------------------------------------------------------------------------
Reference:
Date: Sat, 6 Dec 2014 15:51:16 -0500
From: "JC" < <mailto:[email protected]> [email protected]>
To: < <mailto:[email protected]> [email protected]>, < <mailto:[email protected]>
[email protected]>
Subject: Re: Topband: ARRL160 Test conditions
Hi guys
We have a new class of station this year, few but some European stations
running contest from remote station in US using European call sign, not
W4/xxxx or W7/xxx not even xxx/W4.
Today with the RBN it is easy to confirm where the station is transmitting,
you just need to search the call sign r down load the report with all
reports and filter it using Excel.
First of all , it is illegal to operate in US without a US license not
mention the ethic that does not exist and the Ham radio contest aspect of
the event. Forget about DCXX program the issue is real treat for all of us
that love what we do in 160m.
Check that small report from RBN from EA7PP yesterday night, you can verify
reports up to 52db signal in Virginia RBN station and several over 40 db in
US at the same time 5-15 db in Europe and sometimes up to 24 db in Europe.
<http://www.reversebeacon.net/dxsd1/dxsd1.php?f=0>
http://www.reversebeacon.net/dxsd1/dxsd1.php?f=0
< <http://www.reversebeacon.net/dxsd1/dxsd1.php?f=0&c=ea7pp&t=dx>
http://www.reversebeacon.net/dxsd1/dxsd1.php?f=0&c=ea7pp&t=dx>
&c=ea7pp&t=dx
just unbelievable!!
73's
N4IS
JC
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