Just some basic observations. In order for a dithered clock to solve a regulatory problem, the frequency shift must be greater than the measurement bandwidth. In order for the dithered clock to solve an EMI problem, the frequency shift must be larger than the potential victim¹s bandwidth.
In an ideal world, the measurement and victim BW are the same. This is realized, for instance, in the FM BCB, but not in the television bands. So the immediate question is what is a WiFi channel BW, relative to the 1 MHz (?) BW of the CISPR measurement above 1 GHz. The WiFi BW is considerably larger than 1 MHz in order to support download speeds these days, so it is quite possible for a dithered clock to push the frequency outside the measurement BW but still remain in the WiFi channel, where it can cause mischief. Ken Javor Phone: (256) 650-5261 From: "Grasso, Charles" <[email protected]> Date: Fri, 30 Aug 2013 14:39:15 +0000 To: "[email protected]" <[email protected]> Conversation: Spread Spectrum clocking and adverse WIFI effects Subject: Spread Spectrum clocking and adverse WIFI effects Hello all, Spread spectrum clocking has a *wonderful* effect on radiated emissions especially DDR generated noise. My question is: Given the high degree of integration in today¹s products: Does anyone have concrete experiences of degraded WiFi performance as a result of using SSC? Best Regards Charles Grasso Compliance Engineer Echostar Communications (w) 303-706-5467 (c) 303-204-2974 (t) [email protected] (e) [email protected] (e2) [email protected] - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
