[600MRG] QEX Noise Canceller

[Warren K2ORS]

I did some Googling and found the Quellen (Now part of Intersil) chip:

https://www.intersil.com/en/products/other-analog/noise-canceller/isolation-enhancer-noise-cancellation/QHX220.html

    Its spec'd for 300MHz-3GHz and can reduce noise by 20dB.

73 Warren




On 4/1/2015 2:48 PM, Marshall Cross wrote:
> Yes agree, but Quellen chip is not just subtracting S/Ns out of phase. I don't know their status, check the internet. 73, Marshall W1HK
>
> -----Original Message-----
> From: 600MRG [mailto:600mrg-bounces at w7ekb.com] On Behalf Of Edward R Cole
> Sent: Wednesday, April 01, 2015 1:09 PM
> To: 600MRG at w7ekb.com
> Subject: Re: [600MRG] QEX Noise Canceller
>
> 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.
>>>>
>>

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