In message <OFCBD7CEE0.9955CF45-ON88257785.006913CF-88257785.0069D2AB@US.Schneider-E lectric.com>, dated Fri, 20 Aug 2010, [email protected] writes:
>I'm trying, but failing to understand why phase would be important for >a LISN or for any other transducer used during EMC evaluation. Don't >EMC receivers report received signals as a scalar value? I suppose if the impedance is 50 ohms [1] but not resistive, that can introduce an error or at least affect the 'u-word' (uncertainty). There is a mathematical rationale in Annex I of CISPR 16-1-2 and maybe some further explanation in CISPR 16-4-3 and/or CISPR 16-4-4. [1] It isn't required to be 50 ohms at all frequencies, and need only be within 20% of the required value. The tolerance on the required phase angle is +/-11.5 degrees. Also, the standard says: Where the phase requirement cannot be met, the measured phase angles may be taken into account in the uncertainty budget according to CISPR 16-4-2. Annex I gives guidelines for the calculation of the uncertainty contribution of the phase if the tolerance is exceeded. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK If at first you don't succeed, delegate. But I support unbloated email http://www.asciiribbon.org/ - 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]>
