Conformity Magazine - October 2007 - (Page 48)

Pre-Compliance Measurements Over all, a modern spectrum analyzer with the correct feature set of detectors, correction factors, and troubleshooting tools is an excellent EMI pre-compliance and diagnostic tool. It allows the engineer to quickly determine with excellent accuracy the emissions profile of the DUT, and whether or not it will pass full-compliance testing with a high level of confidence. As mentioned previously, the closer the spectrum analyzer is to a full-compliance receiver in performance, the more confident the engineer will be that the product in question will pass full-compliance testing at a test facility following completion of pre-compliance testing. The large variable here in testing is the site. A fully-compliant test facility tests the performance of the site (e.g., site attenuation). Some of the key characteristics that the engineer should look for when selecting the ideal spectrum analyzer include the following: Measure at Marker Capability: With the measure-at-marker capability, the engineer simply places a marker on a signal of interest, anywhere on the display, and presses the measureat-marker function to measure with up to three different detectors. The specified amplitude accuracy holds true for any point -- on or off the display -- without the need to adjust CISPR Bands A B C D Table 1: Pulse table Frequency Band Bandwidth Pulse Repetition Frequency 1000 Hz 100 Hz 60 Hz 25 Hz 20 Hz 10 Hz 5 Hz 2 Hz 1 Hz Isolated Pulse N/S = Not Specified Table 2: PSA response to CISPR DC pulse 48 Conformity oCtober 2007 reference levels. With a spectrum analyzer’s measure-atmarker capability, the less experienced user can perform accurate measurements as well as the veteran user Accuracy: Frequency and span accuracy is very important in making EMI measurements as it helps ensure the engineer can solve design challenges with fewer iterations. It is important, therefore, for the engineer to return to the same signal that was marked earlier for further evaluation. Identifying the correct problem signal in a crowded signal environment can be very challenging if the spectrum analyzer being utilized has less frequency accuracy. Speed: Measurement speed, like accuracy and performance, is critical for communications and general purpose applications, as it accelerates design verification and enables dramatic improvements in throughput and manufacturing yields. Typically, modern spectrum analyzers feature faster speeds, a much broader usable span and greater amplitude accuracy than traditional spectrum analyzers. With over 8000 data points in a single sweep, the user can measure signals using 120-kHz resolution bandwidth; thereby capturing all signals within the 30 to 1000 MHz span. Wide Breadth of Functionality: The ideal modern spectrum analyzer should be able to correct for transducer factors, Freq Range (MHz) .009 - .15 .15 – 30 30 – 300 300 – 1000 Impulse area uVs 13.5 .316 .044 .044 Reference PRI In Hz 25 100 100 100 Freq (MHz) .15 30 300 1000 9 to 150 kHz 200 Hz EMI BW CISPR Standard Response N/S +4 ±1 dB +3 ±1 dB Reference N/S –4 ±1 dB –7.5 ±1.5 dB –13 ±2 dB –17 ±2 dB –19 ±2 dB PSA nominal DC Pulse Response N/S +3.7 dB +2.7 dB Reference N/S –4.0 dB –7.9 dB –13.0 dB –15.6 dB –16.3 dB 0.15 to 30 MHz 9 kHz EMI BW CISPR Standard Response +4.5 ±1 dB Reference N/S N/S –6.5 ±1 dB –10 ±1.5 dB N/S –20.5 ±2 dB –22.5 ±2 dB –23.5 ±2 dB PSA nominal DC Pulse Response +4.3 dB Reference N/S N/S –6.6 dB –10.5 dB N/S –16.6 dB –16.8 dB –17.0 dB 0.03 to 1 GHz 120 kHz EMI BW CISPR Standard Response +8 ±1 dB Reference N/S N/S –9 ±1 dB –14 ±1.5 dB N/S –26 ±2 dB –28.5 ±2 dB –31.5 ±2 dB PSA nominal DC Pulse Response +7.4 dB Reference N/S N/S –8.4 dB –11.3 dB N/S –12.3 dB –12.3 dB –12.3 dB

Table of Contents Feed for the Digital Edition of Conformity Magazine - October 2007

Contents Editor’s Note Commission Proposes Changes for 57-64 GHz Spectrum Rules FCC Continues Actions Against Jamming Device Distributors Radio Operator Fined for Failing to Make Equipment Available for Inspection Commission Fines Unsolicited Fax Advertisers Firm Offering Quality Standards Training Also Fined Breaking New Ground with Lithium-Battery Generic Requirements for Use in Telecommunications Facilities ESD Open Forum EMC UK 2007 Conference Set Staying Abreast of U.S. E-Waste Legislation EU Commission Establishes RFID Expert Group Update on China's CCC Compliance Program System Level ESD Testing: The Waveforms An Alternative Approach to Surge Suppression Testing Equipment Buyer's Guide EU Scientific Committee Releases Updated Data on EMF Risks Updated Standards List For The EU’s EMC Directive Updated Standards List For The EU’s Directives on Measuring Instruments Call for Presentations for 2008 International ESD Workshop Announced CPSC Actions In The News IEC Standards Update Product Reviews UL Standards Update New Products From Our “You Can’t Make This Stuff Up” Department Looking Back: Items from Past Issues of Conformity Upcoming Events Advertisers

Conformity Magazine - October 2007

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