The "hiss" should be demodulated best in AM mode with a wide bandwidth.
Does it contain any component of grid power? If so, that would be a strong
indication of bad power distribution. If not, dig deeper, but use AM demod
with a wide BW.
Also, in sleuthing interfering RFI, why try to identify WHAT is it? That
really doesn't help much in determining WHERE the source might be. Once
you know the source, you can formulate a fix. Just determining what it
might be really doesn't lead to a fix other than knowing what service to
point a finger at. Do the DFing first.
Dave - WØLEV
On Sat, Dec 23, 2023 at 7:20 PM Frank W3LPL <donovanf@starpower.net> wrote:
> Like all other RFI, the first steps are
>
> 1. turn off all AC power in your own home and turn off
> all UPSes. If the noise disappears, you can use your
> circuit breakers as a next step in isolating the RFI source
>
> 2. If that fails, use a small directional antenna and hand portable
> radio to determine the location of the source
>
> Guessing the source is rarely useful
>
> 73
> Frank
> W3LPL
>
>
>
>
>
> ----- Original Message -----
> From: nlsa@nlsa.com
> To: "Rfi List" <rfi@contesting.com>
> Sent: Saturday, December 23, 2023 7:09:53 PM
> Subject: [RFI] Sources of wideband hiss
>
> Dear friends,
>
> What are some sources of wideband hiss? I'm talking about an unstructured,
> apparently unmodulated many-dB increase in the noise floor across the 2m
> band* No associated birdies or other noticeable signals, just a nasty
> hiss.
> I see it in the direction of high-voltage power lines 2km away and also
> toward a couple of houses I just a few hundred meters distant. The
> mechanisms of those sources are not necessarily the same of course. Ideas
> welcome.
>
> Best regards,
>
> Michael
>
>
>
> *I don't know whether it affects other HF or VHF bands.
>
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>
--
*Dave - WØLEV*
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