Conformity Magazine - October 2007 - (Page 49)

cable loss and amplifier gains,. It should also have the ability to dynamically display limit lines along with margins. For manual troubleshooting and quick visual testing on screen, the spectrum analyzer should feature margin and limit line fail indications. Full-Compliance Measurements If the engineer intends to use the spectrum analyzer for full-compliance testing, as well as pre-compliance testing, then additional functionality must be added to the selection criteria specified above. Selecting a spectrum analyzer that will qualify as a fully compliant EMI measurement receiver requires that the measurement instrument meet two important criteria. First, it must respond correctly to the CISPR pulse test using the quasi-peak detector. The CISPR pulse generator produces DC pulses from 1000 Hz to 1 Hz and an isolated pulse. The pulse widths range from 270 ns to 0.3 ns (see Table 1). The results of performing the CISPR pulse test shows that the modern spectrum analyzer does very well versus the CISPR requirements. There are only a few exceptions and they are in the low repetition rate range. Table 2 compares the CISPR requirements to the performance of the modern spectrum analyzer. The areas of non-compliance with the CISPR requirement is in band A (isolated pulse only), B, C and D when 2 Hz, 1 Hz or an isolated pulse is applied. In band C/D, the 10 Hz pulse is not within specification. Second, it must have an RF preselector. In order to be fully compliant and therefore meet the CISPR 16-1-1 pulse test requirements, the spectrum analyzer must have an RF preselector which can be used to reduce the overloading from large pulses and improve the measurement’s dynamic range. Some dedicated EMI receivers will feature a built-in preselector. Others offer a separate RF preselector which, when used with a specific spectrum analyzer, can turn the measurement instrument into a fully compliant measurement system. Having a separate RF preselector gives the engineer the flexibility to operate the spectrum analyzer as a pre-compliance analyzer, utilizing optional built-in diagnostic tools such as noise figure, phase noise or EMI measurements, or to switch to using the preselector in the filter or bypass mode. Conclusion The spectrum analyzer is a critical component for precompliance and full-compliance EMI testing. In contrast to the traditional spectrum analyzer, modern variations of the measurement instrument typically feature excellent amplitude accuracy on or off display, span and frequency accuracy, correction factors, and limit lines with margins and pass/fail indicators. With over 8000 points across the display, the user has the ability to look at wide spans without missing signals, even in CISPR 16-1-1 specified bandwidths. Selecting a modern spectrum analyzer with these features, as well as the other capabilities highlighted above, will help ensure successful EMI testing -- whether pre-compliance and full-compliance. Couple that with DSP capability over a wide range of bandwidths and detectors, and the engineer has a spectrum analyzer that is suitable for use across a wide range of commercial and MIL-STD applications. Dennis Handlon is a product manager in Agilent’s Wireless Business unit, and can be reached at dennis_handlon@agilent.com. FAST Link www.conformity.com/1070 OCTOBER 2007 CONFORMITY 49 http://www.conformity.com/1070 http://www.wi-spy.com http://www.wi-spy.com

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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