My suggestion: Track it down and then ID it; manufacturers today are employing
'clock dithering techniques' to avoid any specific, individual, high amplitude
single-frequency emissions in order to pass FCC radiated emissions regulations.
As emissions are measured using specific defined bandwidths, this trick spreads
the energy between multiple adjacent 'freq bins' and no individual bin will
break above the regulatory emission spectral limit curve or spec.
Used to be that when I drove around listening on 10m that on a certain freq
above 28.5 MHz that multiple near-on-frequency signals could be heard
heterogeneity together as one drove through the mass of humanity in various
neighborhoods. I think this was due to CRT computer monitors in use the time.
de Jim WB5WPA
From: Mike Ryan <mryan001@tampabay.rr.com>
To: rfi@contesting.com
Sent: Wednesday, May 11, 2016 6:48 AM
Subject: Re: [RFI] Powerline noise humps?
I have some awful noise that is particularly high on 6 meters right now. It
shows up strongest in ssb modes rather than AM. The noise resembles 'wind'
or a 'rushing sound', as if listening to someone talking in a car with a
mobile radio and their window is down. The noise varies, has peaks and
valleys..what a pain in the but. Any ideas? - Mike
-----Original Message-----
From: Jim Brown
Sent: Wednesday, May 11, 2016 12:33 AM
To: rfi@contesting.com
Subject: Re: [RFI] Powerline noise humps?
On Tue,5/10/2016 9:19 PM, David Winarsky wrote:
> - Here is a capture from my waterfall:http://imgur.com/HyuFcyK
My first guess is that it is the clock in some sort of microprocessor.
If the humps drift, they're probably a switching power supply.
73, Jim K9YC
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