Ed Hare spotted the same reference. His comment: "The net effect is that there will now be strong emissions that are strong across wide frequency ranges, not just on specific frequencies."

Dave K1ZZ

-----Original Message-----
From: Bob Vallio [mailto:rbvallio@gmail.com]
Sent: Monday, April 17, 2006 7:41 PM
To: arrl-odv
Subject: Spread Spectrum Noise from Switching Power Supplies

Switching power supplies can generate some nasty RFI spurs.

Now, some designers are turning toward "dithering" the power

supply switching frequency courtesy of a built-in random number

generator. With this approach, instead of having a lot of RFI on

one frequency, the RFI will be thinned out and spread across a

wide spectrum like cheese on a cracker. See:

http://powerelectronics.com/mag/603PET07.pdf

Apparently this is cheaper than building in filter components,

hence improving the profit margin for the manufacturers