I call it "quality noise"
You want just your target noise to invert and cancel.
Anything else will tend to add "new" noises from the pickup antenna.
See here
https://youtu.be/spre7Wn0Kqs
73,
Paul Cianciolo, W1VLF
ARRL EMC Engineer
ARRL - The national association for Amateur Radio™
225 Main Street, Newington, CT 06111-1400 USA
Telephone: (860) 594-0392
FAX: (860) 594-0259
Email: w1vlf@arrl.org
World Wide Web: www.arrl.org
-----Original Message-----
From: RFI <rfi-bounces+pcianciolo=arrl.org@contesting.com> On Behalf Of Mike
Martin
Sent: Wednesday, January 13, 2021 11:57 AM
To: Dave Cole <dave@nk7z.net>
Cc: rfi@contesting.com
Subject: Re: [RFI] Sense antenna for ANC-4 power line rfi?
Hey guys consider this, you can look at a noise on two antennas exactly the
same but located in different places in your yard and see different noises.
That's a fact.
So if you're using a noise cancellation device you can't expect the antenna
you're using for that device to see the same noise that you see when the
antenna with the symptoms. So you have to make sure that the cancellation
device antenna is seeing the same noise that you're picking up in your
receivers and causing interference to the one it's signal. once you achieve
that then the noise cancellation device will work quite well. but if your noise
cancellation device sees a different noise then you're canceling the wrong
noise therefore it doesn't work properly. I wish I had more time to explain
further but unfortunately I'm out here looking for noise and don't have the
time.
Just so you know I also don't have time to proofread my voice to text message
so please excuse the mistakes and type of graphical errors. LOL
Happy 2021,
Mike
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On Jan 13, 2021, 9:15 AM, at 9:15 AM, Dave Cole <dave@nk7z.net> wrote:
>Charles,
>
>You may find that the phase type noise reducers don't work so well on
>power line noise... It can help-- but mostly it will not be very
>effective for distributed RFI sources.
>
>The source of transmission can be distributed, (not in all cases),
>along several hundred, to several thousand feet of power line. This
>means that depending on the distance traveled down the power line, the
>distance to your sense antenna, and the distance to your main antenna,
>RFI will arrive at different times, and hence different phase
>relationships to each other, from every point along the power line that
>
>carries the RFI.
>
>Given that the ANC-4 is a phase cancellation device, (it looks at your
>main antenna, and your sense antenna, and tries to phase cancel an RF
>signal based on phase relationship), this can cause no end of issues.
>
>Now imagine the signals the ANC will see if your RFI is being
>re-radiated along several hundred, or thousand feet of power line. You
>
>will be able to cancel some, but not a lot of the RFI.
>
>If you are lucky, you will have a specular source, and no re-radiation,
>
>which will allow you to cancel most of the offending signal out...
>
>Your idea is a good one, and might help... RFI suppression is always
>fun, when it works... Good luck. Please do post your results.
>
>73, and thanks,
>Dave (NK7Z)
>https://www.nk7z.net
>ARRL Volunteer Examiner
>ARRL Technical Specialist, RFI
>ARRL Asst. Director, NW Division, Technical Resources
>
>On 1/12/21 11:07 PM, Charles Plunk wrote:
>> While waiting on my powerline arc to return in force enough to have
>> confidence it will be ongoing when I call TVA in, thought I would
>play
>> with improving the sense antenna on my Timewave ANC-4. The 3 phase
>power
>> runs at the edge of my lot up to the suspect pole. So the noise is
>> radiating up this way and all the more reason its strong on me I
>> suspect. I have a storage building underneath the lines. I am
>thinking
>> about a vertical made for a scanning receiver I came across and
>mounting
>> it up under the lines on that building. I will tack it up there
>somehow
>> and move it around to get a sweet spot maybe. Any better ideas?
>>
>> Thanks,
>> Chuck
>> AF4O
>>
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