Topband: Quality of RBN data

Sun Dec 7 11:31:15 EST 2014

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.
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> EA7PP signal was s7 when most of Europeans just above noise. But you right I should not accuse people at the first place.
>
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> 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:otradalur at gmail.com]
> Sent: Sunday, December 07, 2014 7:25 AM
> To: topband at contesting.com
> Cc: n4is at comcast.net
> 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.
>
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> Although we will no doubt see cheaters employing remote technology one day, I think your conclusions about cheating based on RBN data are wrong.
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> 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.
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> I had my cluster connection set to show the RBN report for my own transmissions and the results were sometimes "unbelievable" indeed.
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> 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.
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> 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.
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> 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!
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> My transmit antenna - the Arctic King - may be powerful, but it´s not  that powerful ;-)
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> In a contest environment with many strong local stations this problem reaches monumental proportions rendering the RBN reports in many cases meaningless.
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> I think we should take those RBN reports with a grain of salt and not submit unsubstantiated accusations.
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> 73 Thor, TF4M
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> --------------------------------------------------------------------------------------
>
> Reference:
>
>   
>
> Date: Sat, 6 Dec 2014 15:51:16 -0500
> From: "JC" < <mailto:n4is at comcast.net> n4is at comcast.net>
> To: < <mailto:Gary at ka1j.com> Gary at ka1j.com>,    < <mailto:topband at contesting.com> topband at contesting.com>
> 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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