In a message dated 8/24/01, Ken Hall writes: > What equipment is generally used to test the acoustic noise levels specified > in CISPR 24 Annex A while performing Radiated and conducted immunity? >
Hi Ken: There are special microphones and measuring equipment that can be used for acoustic measurements, but often the microphone and preamp end up being exposed to the RF impairment during the radiated immunity test. This introduces the possibility that any demodulated 1 KHz that is measured may come from demodulation within the microphone and preamp, rather than the equipment under test. In general, I think it is better to use Method 2 in Annex A, where the signal is measured as an electrical signal, rather than an acoustic signal. A lowpass filter can be used to keep conducted RF out of the measuring equipment. The use of the reference tone calibration procedure in Method 2 compensates for differences in the nominal gain between the phone line and the point where the signal is being measured. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. http://www.randolph-telecom.com ------------------------------------------- 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: Michael Garretson: [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: No longer online until our new server is brought online and the old messages are imported into the new server.
