[600MRG] QEX Noise Canceller

Wed Apr 1 12:08:39 CDT 2015

Hmm,

I wonder if it was a mini-SDR which in the digital realm notched the 
signal frequency so only noise sidebands were captured and those were 
inverted in phase to cancel noise with only cleaned up signal 
reconverted to analog?

As I understand noise cancelling one needs to take S+N and vector 
subtract N.  Subtraction is accomplished by adding a 180 degree phase 
shifted noise signal.

If you simply take S+N and subtract S+N you get a quiet receiver with 
nothing output.

Does this chip still exist and what does it cost?

73, Ed - KL7uW

At 08:44 AM 4/1/2015, Marshall Cross wrote:
>Lee, I am not an expert on noise cancelling.....however back 5 or 6 
>years we had a contract from NAB to develop an embedded antenna for 
>VHF/UHF DTV reception within laptop/net-book computers. The noise 
>inside such devices at VHF and UHF is very high, even using 
>miniature electro-statically shielded loops it still restricted 
>coverage, so we looked for a way to cancel out the broadband noise 
>created by the digital circuits. What we found, and conducted 
>experiments with, was a chip made by Quellen, Santa Clara, CA. It 
>did not require a separate noise sensing antenna in that it was 
>simply inserted in series with the mini coax from our embedded 
>antenna. And it really worked! So the other day when the subject of 
>needing a second antenna (for noise sampling) with exactly the same 
>characteristics as the main antenna came up, I remembered my work 
>with the Quellen chip which did not require a second antenna.
>Hope this helps, 73, Marshall, W1HK, #41
>
>-----Original Message-----
>From: Lee Mushel [mailto:herbert3 at centurytel.net]
>Sent: Wednesday, April 01, 2015 12:27 PM
>To: Marshall Cross; kgordon2006 at frontier.com
>Cc: 600MRG at w7ekb.com
>Subject: Re: [600MRG] QEX Noise Canceller
>
>Forgive me for asking this but I am not at all sure I've read all 
>the postings on this thread (mechanical breakdown of my snowplow and 
>since I am not at all sure winter is over it such repair came first) 
>but I find it most interesting and I would like to know if any 
>others have stepped up to say
>they have built the QEX noise canceller.   I do have the article sitting
>beside me and one of the things that has intrigued me in the past is 
>my Flex Radio 5000A with two completely independent receivers tied to a common
>oscillator for phase control.   This was done by Flex to provide dual
>diversity operation and, later, to allow virtual "rotation" of fixed
>antennas for noise control and signal enhancement.   While Flex has one of
>their "white papers" which discusses proper operation of this feature I had
>proceeded to install what I felt was a suitable antenna arrangement.   I
>have two DX Engineering Hustler antennas.  One is located next to 
>the House (read "shack") and the other some 350 feet away farther up 
>my hill and fed
>with fairly good Andrew feedline (negligible losses).   I have long used the
>Flex5000A's ability to display simultaneous visual signals from the 
>two antennas and have even extended this idea to allow me to display 
>signals into and outof  two meter local repeaters (much to the 
>dismay of some, I assure you!).
>
>If someone has responded with a "yes, I've built it" I would 
>appreciate it if someone would forward that note to me.  I'd like to 
>know of his
>experience.   Of course, I can easily see the difference in "noise" from my
>present equipment but since I do have some 50 plus years of 
>soldering experience and do have a smart tweezers so I can wind 
>inductors with known values.
>
>73
>
>Lee  K9WRU/32 I guess
>----- Original Message -----
>From: "Marshall Cross" <mcross at megawave.com>
>To: <kgordon2006 at frontier.com>
>Cc: <600MRG at w7ekb.com>
>Sent: Monday, March 30, 2015 11:59 AM
>Subject: Re: [600MRG] QEX Noise Canceller
>
>
> > Then why not use the same antenna with a splitter?
> >
> > Sent from my iPhone
> >
> >> On Mar 30, 2015, at 12:32 PM, Kenneth G. Gordon
> >> <kgordon2006 at frontier.com> wrote:
> >>
> >>> On 30 Mar 2015 at 8:56, Frank Lotito wrote:
> >>>
> >>> Has anyone tried the noise canceller circuit presented in the Jan / Feb
> >>> 2012
> >>> issue of QEX? Specifically, for the 600 / 630 meter bands?  The article
> >>> by Fred
> >>> Brown, W6HPH, is titled "End Man-Made Noise with the Noise Canceller,"
> >>> pages 12
> >>> through 14.  The author alludes to tailoring the design for the
> >>> frequency band
> >>> of interest.  The QEX article presents a 75 meter design.
> >>>
> >>> 73 Frank K3DZ / WH2XHA
> >>
> >> Frank (and others):
> >>
> >> There was a truly excellent article in Electric Radio Magazine for
> >> February
> >> 2014 on noise cancellers by Mike Murphy WU2D.
> >>
> >> The final unit he described both reduced his own noise level by +25 dB
> >> and
> >> is adaptable, easily, to any band or frequency.
> >>
> >> He made the point that for any noise canceller, the only really effective
> >> "noise antenna" is an exact duplicate of your normal receiving antenna.
> >>
> >> Mike is quite a character and is very talented. I sometimes wish he was a
> >> member of this forum.
> >>
> >> Ken W7EKB
> >>
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> >>
> >>
> >>
> >
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>
>
>
>
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73, Ed - KL7UW
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