Eric,
The measurement at the port for the band edge would not be appropriate, cause you would not take into account the variation of the antenna gain, which is not be flat in the 2.4 Ghz band ( I am assuming that you are testing a FHSS or DSSS device) In any case the method that you described, was developed to overcome of the problem of average measurement for FHSS device since the signal is hopping. This method allow you , in a way, to determine the average measurement at the band edge. We did some experiment here in your lab with some WLAN companies with some units capable to transmit at 100 percent duty cycle and with a 50 percent duty cycle. For first configuration we were performing a direct average measurement at the band edge , and for the second configuration we were using the delta marker method. The results were only different by 1 dB. Rachid Sehb Rhein Tech Laboratories, Inc. 360 Herndon PKWY, suite 1400 Herndon, VA 20170 From: Eric Penne [mailto:[email protected]] Sent: Wednesday, August 06, 2003 11:44 PM To: [email protected] Subject: Apples and ? comparison of dBuV/m I've been perusing some FCC test reports and had a question that I couldn't find an answer to. I'm trying to brush up on my skills so I can get a job in the EMC industry again. Funny thing my former employer told me. I had my picture in the Fall 2002 issue of the IEEE EMC newletter 4 times at the Minneapolis EMC Symposium. Unfortunately I was laid off 1 week after the show. :) Anyway, on a couple of the reports, measurements were taken to verify that a transmitter didn't exceed the limits of a band next to it. The EUT including antenna was tested in a chamber and the maximum value in average and peak testing was found in dBuV/m. The unit is operating above 1GHz. To verify the band edge measurements the transmitter was directly connected to a spectrum analyzer and power measurements were taken to find the overall peak and the peak in the restricted band. The difference of the direct connection Spec Analyzer test was subtracted from the maximum average value in the radiated emissions test to say that the EUT passed in the restricted band. What I couldn't understand was how an average value from the RE scan with a Res BW of 1MHz could subtract a peak value from the power scan that has a Res BW of 100kHz? Is an average value with 1MHz RBW equal to a Peak value with 100kHz RBW? Thanks, Eric This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ 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] Archive is being moved, we will announce when it is back on-line. 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.ewh.ieee.org/soc/emcs/pstc/ 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] Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
