Richard, Up to 6 dB on a system with cables. 3 to 4 dB on floor standing equipment and no cables. 2 - 3 dB on table top and no cables. Today we measured a 6ft telecom rank with one module and several cards and several cables. Some cables went under the floor, some laid on the turntable, and some were routed in Telcordia cable tray fashion. The highest deviation was 4.2 dB.
Regards, Dale Albright ----- Original Message ----- From: <[email protected]> To: <[email protected]>; <[email protected]> Sent: Wednesday, January 12, 2000 2:41 PM Subject: RE: Chamber and OATS Coorelation > Dale, what correlation error are you obtaining? > Richard Woods > > ---------- > From: Dale Albright [SMTP:[email protected]] > Sent: Wednesday, January 12, 2000 12:57 PM > To: [email protected]; [email protected]; > [email protected] > Cc: [email protected] > Subject: Re: Chamber and OATS Coorelation > > > Don, > > We have made correlation between our chamber and OATS using the CNE > meter at > several positions in the "uniform field" of the chamber. Chamber > antenna > fixed, Oats antenna scanned. We have created a correction table > whereby one > point or an average of several points can be used depending on the > particular EUT you are testing. If you have knowledge of where the > EUT is > emitting, maybe a top slot of a 6ft cabinet, you can elect to apply > a > specific correction. Or if the EUT is small, then the average of 4 > points > may cover the area of the EUT. We have gotten very good results. > However, > when cables are involved, correlation goes down. Our next run will > include > the several positions on the OATS also. > > Best Regards, > > Dale Albright. > > > > > > ----- Original Message ----- > From: <[email protected]> > To: <[email protected]>; <[email protected]> > Cc: <[email protected]> > Sent: Wednesday, January 12, 2000 8:16 AM > Subject: RE: Chamber and OATS Coorelation > > > > > > Barry, > > > > Thank you for your comment. What we are trying to do is establish > better > > correlation between the chamber and OATS so we minimize our time > in the > > heat, humidity, rain and bugs (South Florida) at the OATS. We are > not > > trying to replace the OATS with the chamber. > > > > We have recently been evaluating a REFRAD for correlation > purposes. So > far > > the results with the REFRAD factors have been very good. The > emission in > > the chamber was 7 dB off from the OATS value, but this correlated > to > within > > 1 dB of what was predicted by the REFRAD. I admit our sample > universe is > > small at this time with only a handful of emissions to compare to. > But > > these first results are promising. > > > > Don Umbdenstock > > Sensormatic > > > > > > > > > > > ---------- > > > From: Barry Ma[SMTP:[email protected]] > > > Reply To: Barry Ma > > > Sent: Tuesday, January 11, 2000 5:55 PM > > > To: [email protected] > > > Cc: [email protected] > > > Subject: RE: Chamber and OATS Coorelation > > > > > > > > > Mirko, > > > > > > I happen to have a copy of CISPR 16-1 at hand. Clause 16.6 "Open > area > site > > > validation procedure" reads: > > > > > > ... The deviation between a measured NSA value and the > theoretical value > > > shall not be used as a correction for a measured EUT field > strength. > This > > > procedure shall be used only for validating a test site. ... > > > > > > The above statement is not followed by any explanation. What do > you > think > > > the reason is? My guess is that there are lot of factors causing > > > inaccurate E-field measurement. The collective result of those > factors > > > cannot be simply corrected by changing antenna factors. > > > > > > At the end of your message, however, you stressed on "for a > specific > test > > > setup". May we try this "illegal" correction procedure with > caution only > > > "for a specific test setup" and for a specific frequency range? > Hopefully > > > it might be worthwhile to try. > > > > > > Barry Ma > > > Anritsu Company > > > Morgan Hill, CA > > > ----------- > > > On Tue, 11 January 2000, "Matejic, Mirko" wrote: > > > > > > Richard, > > > > > > You could improve correlation by adjusting chamber antenna > factors for a > > > correlation differences which you can get from NSA measurements > one at > > > OATS the other in the chamber with a fixed antenna height. You > could > also > > > determine correlation differences by comparing measured field > strength > > > levels from battery powered comb generator. > > > > > > Fixed vs. 1-4m antenna height among other factors will always > create > > > unpredictable correlation for a specific test setup. > > > > > > Mirko Matejic > > > > > > > > > ______________________________________________________________ > > > > > > Free Internet Access from AltaVista: Get it, share it & win! > > > http://freeaccess.altavista.com/pika/www/initweb.jsp > > > > > > > > > --------- > > > This message is coming from the emc-pstc discussion list. > > > To cancel your subscription, send mail to [email protected] > > > with the single line: "unsubscribe emc-pstc" (without the > > > quotes). For help, send mail to [email protected], > > > [email protected], [email protected], or > > > [email protected] (the list administrators). > > > > > > > > > > --------- > > This message is coming from the emc-pstc discussion list. > > To cancel your subscription, send mail to [email protected] > > with the single line: "unsubscribe emc-pstc" (without the > > quotes). For help, send mail to [email protected], > > [email protected], [email protected], or > > [email protected] (the list administrators). > > > > > > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to [email protected] > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to [email protected], > [email protected], [email protected], or > [email protected] (the list administrators). > --------- This message is coming from the emc-pstc discussion list. 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