[RFI] Powerline noise humps?

[JW]

Yup.Many returns on 'clock dithering' too. This could have saved us some blood and sweat at a critical time (EMI pre-screening) a few years back on a new product but the digi-whizes had not incorporated that feature in their design ...
https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=clock%20dithering%20emi

de Jim WB5WPA

      From: Charles Coldwell <coldwell at gmail.com>
 To: JW <jwin95 at yahoo.com> 
Cc: Mike Ryan <mryan001 at tampabay.rr.com>; "rfi at contesting.com" <rfi at contesting.com>
 Sent: Wednesday, May 11, 2016 10:24 AM
 Subject: Re: [RFI] Powerline noise humps?
   
On Wed, May 11, 2016 at 8:40 AM, JW via RFI <rfi at contesting.com> wrote:
> ... manufacturers today are employing 'clock dithering techniques' to avoid any specific, individual, high amplitude single-frequency emissions

Also known as "spread spectrum clocking" (a nice search-engine term).
Lots of PLLs on the market advertise this feature.  USB 3.0 uses it on
the high-speed conductors to avoid the need for shielded cables.

-- 
Charles M. Coldwell, W1CMC
Belmont, Massachusetts, New England
"Turn on, log in, tune out"