Notch filters are a good option if you can find one for your application. However you do need to "calibrate" them to get attenuation factors well above and below the notch frequency. You will find that they usually have significant attenuation at harmonics of the notch frequency of the filter. We will often use a notch filter near the fundamental of the transmitter, and then high-pass filter once beyond that. Custom designed filters are sometimes necessary.
Bill -----Original Message----- From: James Pawson (U3C) [mailto:[email protected]] Sent: Wednesday, July 26, 2017 2:13 AM To: [email protected] Subject: Re: [PSES] application of CISPR 32 to EUTs with integrated radio transmitters Hi Balmukund, A good point. I've certainly used notch filters in the past for removing the intentional radiator to prove that the second harmonic is in fact an artefact of the measuring instrument. I've also done this by increasing the attenuation on the input to the analyser until the second harmonic suddenly reduces by more than the amount of attenuation inserted - I'm sure I read about that technique on this forum. I guess if you took into account the loss vs frequency characteristics of the filter in your measurement factors then I can't immediately see a reason why you couldn't use one. Would be interested to hear other opinions on the topic. James Pawson Unit 3 Compliance -----Original Message----- From: Balmukund Vyas [mailto:[email protected]] Sent: 26 July 2017 05:11 To: [email protected] Subject: Re: [PSES] application of CISPR 32 to EUTs with integrated radio transmitters Is it possible to use notch filters and measure rest of the frequencies? -----Original Message----- From: T.Sato [mailto:[email protected]] Sent: 25 July 2017 17:41 To: [email protected] Subject: Re: [PSES] application of CISPR 32 to EUTs with integrated radio transmitters Hello members, Thanks all who responded. I hope CISPR makes this topic clear in near future. Regards, Tom -- Tomonori Sato <[email protected]> URL: http://t-sato.in.coocan.jp On Sat, 22 Jul 2017 03:10:27 +0900, "T.Sato" <[email protected]> wrote: > Hello members, > > I want to hear of your opinion - while emission measurement for CISPR > 32, integrated radio transmitters must transmitting? > > > Although the standard is not clear whether radio transmitter can be > set off in emission measurement, I believed we can set radio transmitter off, as: > > - CISPR 32 said "The radiated emission requirements in this standard > are not intended to be applicable to the intentional transmissions from a radio transmitter as defined by the ITU, nor to any spurious emissions related to these intentional transmissions." > > - If non-transmitter function of the equipment (such as CPU clock and harmonics) generates emissions in the frequency band of the intentional transmission of the transmitter (such as 2.4 to 2.5 GHz), I think we should apply the emission limits as the emissions are not related to the intentional transmissions. However, it is difficult to measure such emissions in presence of the intentional transmission. > > - The standard says "Compliance can be shown by measuring the EUT's emissions when operating its functions simultaneously, individually in turn, or any combination thereof." So, even if emissions from the transmitter function must also be considered in the standard, it should permissible to test non-transmitter function of the equipment while transmitter is set off. > > - Then, if the transmitter function of the equipment is tested while > all the other functions are set off, all the emissions measured are those caused by the transmitter. > > > However, I heard of strong opinions that the emission measurement must > be run while the integrated radio transmitter is transmitting, and all the emissions in the frequency bands of intended transmissions and those harmonics should be simply ignored. > > > What do you think about this? > > Regards, > Tom > > -- > Tomonori Sato <[email protected]> > URL: http://t-sato.in.coocan.jp > > - > ---------------------------------------------------------------- > 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://www.ieee-pses.org/list.html (including how to > unsubscribe) 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. 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