Yes, scale on right applies to pan adapter bin size. Scale in the
frequency window is for energy in the 6khz filter.
The picture was one I grabbed a while ago. Just grabbed 2 more that I will
upload this evening. They look the same, but even more uniform. Will also
upload audacity file.
Yes, captured the remote location via Flex SmartSDR software from my home
station.
On Mon, Nov 24, 2025, 1:47 PM Michael Carter <Mike.Carter@unh.edu> wrote:
> Thanks for the panadapter picture, Jeff. The spectrum is remarkably
> uniform.
>
> I am not familiar with the Flex panadapter display presentation. The
> scale on the right side of the spectrum display suggests a noise level of
> -90 (units unknown, reference level unknown, but the small S-meter window
> says -71 dBm. Is that the total power in the indicated passband, which
> appears to be about 4 kHz wide? The bandwidth displayed in the S-meter
> window says '6K' - is that the actual DSP bandwidth?
>
> I do see the faint spectral lines in the waterfall that Don, WD8DSB
> mentioned.
>
> Finally, the date/time stamp on the spectrum window is from one year ago,
> and apparently obtained from your Flex radio (if the W4DD-1 annotation so
> indicates). Were you monitoring the offending RFI source from your home or
> remotely near the suspect residence?
>
> 73,
> Mike, K8CN
> ------------------------------
> *From:* RFI <rfi-bounces+mike.carter=unh.edu@contesting.com> on behalf of
> Jeff (W4DD) <w4dd09@gmail.com>
> *Sent:* Monday, November 24, 2025 11:17 AM
> *To:* rfi@contesting.com <rfi@contesting.com>
> *Subject:* [RFI] FW: RFI Signature
>
> [You don't often get email from w4dd09@gmail.com. Learn why this is
> important at https://aka.ms/LearnAboutSenderIdentification ]
>
> CAUTION: This email originated from outside of the University System. Do
> not click links or open attachments unless you recognize the sender and
> know the content is safe.
>
>
> Thanks to all that replied. Some interesting thoughts to consider. I had
> a
> couple of Laughs also since several experts mentioned things I had been
> thinking. I had pulled out a lawn tool battery charger (K9MA) and
> experimented with that. It did produce a similar spectrum display, but I
> still can't account for why the source would be mostly at power level 2 or
> 3. Seems like the battery would eventually be charge and it would drop to
> level 4, which we seldom see. My battery was fully charged and the noise
> level was very low.
>
>
>
> A demand driven device (K8CN), seems logical. It is not related to wx and
> does not change based on outdoor temperature so likely not HVAC. POE is an
> interesting idea I had not considered.
>
>
>
> A ckt brkr based sniffer (WD8DSB). I actually built one of those (thanks
> Don). Unfortunately, the neighbor is resistant to anyone entering the
> home.
> This is also a remote assist, so I don't get to actually visit the site.
>
>
>
>
>
>
>
> For those that asked, here is a waterfall capture. Noise at the -71/-72
> level (level 2 of 4 levels).
>
> Antenna is a multiband vertical, tuned to 3540KHz.
>
>
>
>
>
>
> https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdrive.google.com%2Fdrive%2Ffolders%2F1jYH07St1bSd0-Coqhl76HhraKbdYX2e-%3Fusp&data=05%7C02%7Cmike.carter%40unh.edu%7C46bfc69c7ad748e135eb08de2b74fd01%7Cd6241893512d46dc8d2bbe47e25f5666%7C0%7C0%7C638995980445207825%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C80000%7C%7C%7C&sdata=jynEmH2qEkA%2FHhBGItq2zkY0%2F4SdOWvb3hpP%2FWWizHk%3D&reserved=0
> <https://drive.google.com/drive/folders/1jYH07St1bSd0-Coqhl76HhraKbdYX2e-?usp>
> =drive_link
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> _____
>
> From: RFI < <mailto:rfi-bounces+mike.carter=unh.edu@contesting.com
> <rfi-bounces+mike.carter=unh.edu@contesting.com>>
> rfi-bounces+mike.carter=unh.edu@contesting.com> on behalf of Jeff (W4DD) <
> <mailto:w4dd09@gmail.com <w4dd09@gmail.com>> w4dd09@gmail.com>
> Sent: Sunday, November 23, 2025 2:10 PM
> To: <mailto:rfi@contesting.com <rfi@contesting.com>> rfi@contesting.com <
> <mailto:rfi@contesting.com <rfi@contesting.com>> rfi@contesting.com>
> Subject: [RFI] RFI Signature
>
>
>
> [You don't often get email from <mailto:w4dd09@gmail.com
> <w4dd09@gmail.com>> w4dd09@gmail.com.
> Learn why this is important at
> <https://aka.ms/LearnAboutSenderIdentification>
> https://aka.ms/LearnAboutSenderIdentification ]
>
> CAUTION: This email originated from outside of the University System. Do
> not
> click links or open attachments unless you recognize the sender and know
> the
> content is safe.
>
>
> I am working on a RFI case that we believe is coming from a nearby home.
> The owner is a little cooperative, but is not interested in doing a ckt
> breaker test. The noise exhibits some interesting characteristics that may
> help us in suggesting he unplug a device. Perhaps someone has seen this
> before.
>
>
>
>
>
> 1. On the pan adapter, looks like power line noise. Random dots
> across
> the screen.
> 2. No repeating clusters of noise vs frequency that might suggest a
> SMPS.
> 3. No correlation to sunlight or darkness. No correlation to time of
> day.
> 4. Has distinct levels of interference; we have noted -85dBm, -78dBm,
> -72dBm (S-9), -66dBm. Interesting the levels are about 6dB apart. -78 and
> -72 are most common.
> 5. The neighbor has a solar system installed roughly 2 years ago, but
> as mentioned, no correlation to sunlight/darkness or time of day.
> 6. Affects mostly 80M but can be heard on other bands
>
>
>
> Has anyone seen 4 levels of noise from a device before?
>
>
>
> Thanks for any ideas.
>
>
>
>
>
> Jeff, W4DD
>
>
>
>
>
>
>
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