There is some variance as to the appropriate VBW setting to make an accurate average measurement. As I recall there is (and I have forgotten what it is) a ratio that must be maintaied between the RBW and the VBw settings. Our Spectrum Analyzer uses a 30Hz bandwidth setting (for conducted emissions) but one lab mentioned that a 1kHz VBw should be the minimum.
Chas Grasso From: [email protected] [mailto:[email protected]]On Behalf Of Ralph McDiarmid Sent: Monday, August 23, 2004 9:45 AM To: '[email protected]' Subject: RE: Average Detection It's my understanding that the 10Hz VBW provides a filter time-constant approximating that of an average detector. Ralph McDiarmid, AScT Compliance Engineering Group Xantrex Technology Inc. > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Tom Cokenias > Sent: August 23, 2004 6:51 AM > To: Ridler, Samantha; '[email protected]' > Subject: Re: Average Detection > > > Hello Samantha, > > For analyzers that do not incorporate an average detector, > the FCC has specified settings of RBW 1 MHz and VBW of 10 Hz > for average measurements in other parts of the Rules for > measurements above 1 GHz. They have been accepting these > settings for many years for spread spectrum and now 802.11 > radios operating under 15.247 of the Rules. > > best regards > > Tom Cokenias > > T.N. Cokenias Consulting > P.O. Box 1086 > El Granada CA 94018 > > tel 650 726 1263 > fax 650 726 1252 > > cell 650 302 0887 > > At 8:21 AM +0100 8/23/04, Ridler, Samantha wrote: > >Hello All > > > >FCC part 18 requires the use of an Average detector. For > measurements > >above 1GHz on a HP8593E EMC (Spectrum) analyser, would > using a Video > >Average of 100 or more be equivalent to taking a measurement with an > >Average detector? > > > > > >It has been suggested to me by a test house that this is the > case, but > >I have not managed to find any rationale for this. > > > >The setup for the Analyser in question during the measurent was as > >follows if this helps: SPAN = 2GHz, RBW =1MHz, VBW = 3MHz, > SWEEP =40ms > > > >Many thanks. > > > >Samantha Ridler BEng MIEE > >Compliance Engineer > > > >---------------------------------------------------------------- > >This message is from the IEEE Product Safety Engineering Society > >emc-pstc discussion list. Website: http://www.ieee-pses.org/ > > > >To post a message to the list, send your e-mail to [email protected] > > > >Instructions: > >http://listserv.ieee.org/listserv/request/user-guide.html > > > >List rules: http://www.ieee-pses.org/listrules.html > > > >For help, send mail to the list administrators: > > > > Ron Pickard: [email protected] > > Dave Heald: [email protected] > > > >For policy questions, send mail to: > > > > Richard Nute: [email protected] > > Jim Bacher: [email protected] > > > >All emc-pstc postings are archived and searchable on the web at: > > > > http://www.ieeecommunities.org/emc-pstc > > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > > Instructions: > http://listserv.ieee.org/listserv/request/user> -guide.html > > > List rules: > http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Ron Pickard: [email protected] > Dave Heald: [email protected] > > For policy questions, send mail to: > > Richard Nute: [email protected] > Jim Bacher: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
