it's probably a 1-2 day job to get it set up and going. A simpler method is to reduce the RBW until you can see the EUT through the radio station. This works well if the EUT signal is narrow enough. I believe that if you go below 3 kHz then the quasi-peak detection attack time slows.
Dave Cuthbert From: Ken Javor [mailto:[email protected]] Sent: Wednesday, January 28, 2004 12:57 PM To: drcuthbert; [email protected]; [email protected]; [email protected] Subject: Re: OATS Measurement if you can make that work in a reasonable amount of time, you are a much greater wizard than I... > From: [email protected] > Date: Wed, 28 Jan 2004 11:45:39 -0700 > To: <[email protected]>, <[email protected]>, > <[email protected]>, <[email protected]> > Subject: RE: OATS Measurement > > Isn't this allowed? Measure the EUT in the chamber to see if the signal at > this particular frequency is an issue. Say it's 10dB below the limit- then why > bother getting an accurate OATS measurement? But if it is 3dB below the limit > then you have probably do have to obtain an accurate OATS measurement. > > How to work around the radio station short of taking it off the air for a few > minutes? You could lower radio station signal at the OATS antenna by 10 dB or > so by cancellation. Receive the radio station on an antenna 30 meters from the > OATS. Amplify it and re-radiate it 5 meters from the OATS. Adjust the > amplitude (attenuator) and phase (insert lengths of coax if you don't have a > phase shifter)until the radio station is largely nulled out. You would want > the OATS antenna at a fixed height or else you will have to adjust amplitude > and phase for each change in antenna height. Is this allowed? > > Dave Cuthbert > Micron Technology > > -----Original Message----- > From: [email protected] > [mailto:[email protected]]On Behalf Of Ken Javor > Sent: Wednesday, January 28, 2004 10:50 AM > To: Grasso, Charles; 'Tsang Steven'; '[email protected]' > Subject: Re: OATS Measurement > > > > 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 > 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
