Mr. Grasso and I disagree. He comes from a point of strength (his knowledge and expertise in modeling), and I, from a position of weakness (little knowledge and less interest in predictive techniques).
If I were concerned whether the EUT were emitting at a particular frequency, and if I had a screened or anechoic chamber, I would do the following very quick test (realizing this doesn't answer the original post's question, except in a basic operational sense): I would put the EUT and a radio tuned to the offending ambient station in the chamber. I would pull the door to until radio reception was just marginal. Then I would energize the EUT and monitor effect on radio reception. I would move the radio as close to the EUT as I could to see if there was any response, but I would use the response at roughly three meters as a gauge of whether there would be a real problem. > From: "Grasso, Charles" <[email protected]> > Date: Wed, 28 Jan 2004 10:28:18 -0700 > To: "'Ken Javor'" <[email protected]>, "'Tsang > Steven'"<[email protected]>, > "'[email protected]'"<[email protected]> > Subject: RE: OATS Measurement > > I must disagree. I would cite Mr Leferinks paper from the Boston EMC > Symposium. In it he concluded that > a) correlation was possible for tuned dipoles to +/- 4db - an 8dB swing.and > b) for test objects the variation in field strength can be as high as 40dB > for "actual EUTs" and therefore correlation between different radiated > emissions test methods is impossible. > > I think its time we use predictive techniques rather than correlation > techniques between test facilities. There will be a paper in the Santa > Clara Symposium this year addressing just this issue. > Best Regards > Charles Grasso > Senior Compliance Engineer > Echostar Communications Corp. > Tel: 303-706-5467 > Fax: 303-799-6222 > Cell: 303-204-2974 > Email: [email protected]; > Email Alternate: [email protected] > > > -----Original Message----- > From: Ken Javor [mailto:[email protected]] > Sent: Wednesday, January 28, 2004 7:25 AM > To: Tsang Steven; [email protected] > Subject: Re: OATS Measurement > > > Is the (semi?) anechoic measurement a 3 meter measurement? If it is and it > meets the NSA curve, you ought to be able to correlate your anechoic and > OATS measurements reasonably well. If they correlate where you don't have > ambients, you ought to be able to use the anechoic measurement in lieu of > the OATS measurement where the ambient intervenes. > >> From: "Tsang Steven" <[email protected]> >> Reply-To: "Tsang Steven" <[email protected]> >> Date: Wed, 28 Jan 2004 12:41:22 +0800 >> To: [email protected] >> Subject: OATS Measurement >> >> >> Dear all, >> I have a question regarding on OATS measurement (3m site, 30MHz to > 1000MHz), I >> hope someone could help me on this issue. >> Currently my company is undergoing a accreditation porcess and the > accreditor >> is asking on the method of testing to overcome the issue of the noise > floor >> covering the signal generate from the EUT (i.e. Radio station signal ). >> We have propose to measure the signal from EUT in an aechoic chamber and > use a >> signal generator to simulate the signal with a change of frequency (i.e. >> 10kHz) to avoid the signal being block by the noise floor and re-measure > the >> signal on OATS. >> This method is rejected by the assessor and asking to provide an > alternative >> method. Could someone provide the solution, thanks!!! >> >> Best Regards, >> >> emc_st >> >> _________________________________________________________________ >> ??? : ???, ????? http://go.msnserver.com/HK/34698.asp >> >> >> ------------------------------------------- >> This message is from the IEEE EMC Society Product Safety >> Technical Committee emc-pstc discussion list. >> >> Visit our web site at: http://www.ieee-pses.org/ >> >> To cancel your subscription, send mail to: >> [email protected] >> with the single line: >> unsubscribe emc-pstc >> >> 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 EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ieee-pses.org/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > 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 EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc 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
