That input was a reply to Mr. Haynes who advocated slowing down the sweep. Ken Javor
Phone: (256) 650-5261 > From: Derek Walton <[email protected]> > Date: Wed, 13 May 2009 15:58:30 -0500 > To: Ken Javor <[email protected]> > Cc: Untitled <[email protected]> > Subject: Re: Dimmer Switch > > Whoa Ken! > > I'm not advocating any test techniques here. > > I am in total agreement with 461F. > > Always have been. > > Sent from my iPhone > > On May 13, 2009, at 1:55 PM, Ken Javor <[email protected]> > wrote: > >> MIL-STD-461F deals with this just the opposite of what you say - >> increases >> the sweep speed and puts analyzer in max or peak hold mode. The >> total time >> taking the multiple fast sweeps must be at least as long as using the >> default sweep times for a single sweep. The idea is to specifically >> catch >> signals which are time synchronized, not frequency stable, relative >> to the >> analyzer bandwidth. >> >> Ken Javor >> >> Phone: (256) 650-5261 >> >> >>> From: "Haynes, Tim (SELEX GALILEO, UK)" <[email protected]> >>> Date: Wed, 13 May 2009 17:03:52 +0100 >>> To: Derek Walton <[email protected]>, John Woodgate <[email protected] >>>> >>> Cc: <[email protected]> >>> Conversation: Dimmer Switch >>> Subject: RE: Dimmer Switch >>> >>> Hi All, >>> >>> I think that I would describe it as the following, >>> >>> Every t=1/50 seconds current flows and this has a fast rise time. The >>> net effect is a comb occurring in the frequency domain every 50Hz, >>> however, this comb only appears every 1/50 (=20)ms. >>> >>> If the sweep is, say 20ms for the whole screen - then one, possibly >>> 2 of >>> these time domain events will show on the screen. >>> >>> In order to correctly display this type of signal, the sweep time >>> should >>> be slowed and the frequency range adjusted until each 50Hz element is >>> displayed. >>> >>> A quick answer to something that could take a lot of explaining - may >>> mean that there are limitations to the answer! >>> >>> Regards >>> Tim >>> (Off home now) >>> >>> ************************ >>> >>> Tim Haynes A1N10 >>> >>> Electromagnetic Engineering Specialist >>> >>> SELEX Sensors and Airborne Systems >>> >>> 300 Capability Green >>> >>> Luton LU1 3PG >>> >>> ( Tel : +44 (0)1582 886239 >>> >>> 7 Fax : +44 (0)1582 795863 >>> >>> ) Mob : +44 (0)7703 559 310 >>> >>> * E-mail : [email protected] >>> >>> P Please consider the environment before printing this email. >>> >>> >>> >>> There are 10 types of people in the world-those who understand binary >>> and those who don't. J. Paxman >>> >>> >>> -----Original Message----- >>> From: [email protected] [mailto:[email protected]] On Behalf Of Derek >>> Walton >>> Sent: 13 May 2009 16:04 >>> To: John Woodgate >>> Cc: [email protected] >>> Subject: Re: Dimmer Switch >>> >>> *** WARNING *** >>> >>> This message has originated outside your organisation, >>> either from an external partner or the Global Internet. >>> Keep this in mind if you answer this message. >>> >>> >>> I think you are missing th point John, I'm not saying harmonics >>> aren't >>> there: I've stressed harmonic rich as much as I can..... >>> >>> It's all down to what you see on the display of the SA, and thats >>> sweep >>> time dependent. Ken describes that well. >>> >>> The lines that appear on the display are spaced on sweep time not >>> frequency. >>> >>> It would be useful to show graphs on the group! >>> >>> Cheers, >>> >>> Derek. >>> >>> >>> John Woodgate wrote: >>>> In message <c630442d.4265c%[email protected]>, dated >>>> Wed, 13 >>> >>>> May 2009, Ken Javor <[email protected]> writes: >>>> >>>>> Have to admit to being confused by the Woodgate-Walton discussion. >>>>> The way I see it, the dimmer switch is indeed generating a harmonic >>>>> rich signal. The spectrum analyzer, due to the required EMC >>>>> bandwidths, doesn't show each individual harmonic - the bandwidth >>>>> is >>>>> wider than the harmonic spacing. Therefore the dimmer switch is >>>>> creating what appears to be broadband noise, as long as your >>>>> reference point is audio frequency bandwidths necessary for radio >>>>> communications, and by extension EMI measurements. >>>> >>>> I agree. The harmonics are there, whatever you can or can't see on >>>> the >>> >>>> SA display. >>> >>> - >>> ---------------------------------------------------------------- >>> This message is from the IEEE Product Safety Engineering Society >>> emc-pstc discussion list. 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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.ieeecommunities.org/emc-pstc >>> Graphics (in well-used formats), large files, etc. can be posted to >>> that URL. >>> >>> 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.ieeecommunities.org/emc-pstc >> Graphics (in well-used formats), large files, etc. can be posted to >> that URL. >> >> 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.ieeecommunities.org/emc-pstc > Graphics (in well-used formats), large files, etc. can be posted to that URL. > > 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.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. 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]>
