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Re: [CQ-Contest] Understanding the dynamic error free RBN algorithm

To: cq-contest@contesting.com
Subject: Re: [CQ-Contest] Understanding the dynamic error free RBN algorithm
From: Pete Smith N4ZR <n4zr@contesting.com>
Date: Wed, 24 Jul 2013 07:40:03 -0400
List-post: <cq-contest@contesting.com">mailto:cq-contest@contesting.com>
I have gone through the same process that Bret describes, and found only a couple such instances out of thousands of spots on one day.

So I guess I need to ask again - will you make your methods and data public, Bret?

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 7/23/2013 8:48 PM, Brett Graham wrote:
DJ7WW added:

Very true and a contester already adressed a contest sponsor and insisted on disqualification of his competitor (ahead of him of course), whos harmonic
was shown on a different band in RBN.

73
Peter

-----Original Message-----

S56A4ZR said:

> Real life 0IF RX could achieve 60 dB unavoidable image rejection and
> this is not enough in contests. Our ham freqs are NOT channelized
> although one knows where the image is!
The most popular version of QSD receiver has EVEN HIGHER response at
harmonics of its LO than -60 dBc

Though it should be noted that the LO spurious response of QSD receivers does not appear on multiples of the frequency the signal is really on.

Direct sampling SDRs can have a spurious response that will appear on multiples of the frequency the signal is really on. Or AROUND the multiple of the frequency the signal is really on, as can be seen from RBN spots.

CT1BOH has shown multi-multis who might find themselves behind DR1A in the next CQ WW the basis for making the same complaint.

I found it easier to see the spurious responses of the various SDR architectures from looking at RBN spots on weekdays, as the few DXpeditions or special event stations that might actually be on >1 band simultaneously are easy to find/exclude.

Figuring out which RBN spots or signals in a recording from a SDR are actually there as the station has >1 transmitter QRV or is really a fecal signal - or is just a spurious response of the SDR - should make for a good challenge.

73, ex-VR2BG/p.

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