Pat: This doesn't really answer your CISPR question, but, FYI, the USA Mil-Std-461D does define the LISN construction. It then directs you to add the loss between the power line and the RF port to the cable loss and the observed signal. Their limit figure is in terms of dBuV of emission riding on the powerline.
Going back in time, the USA Mil-I-6181, which governed prior to 1968, also defined the LISN's, but in those days, we hadn't even begun to think about the powerline-to-port loss. The FCC doesn't mention (IIRC) this loss specifically, but since their limits are also referred to as powerline emission voltages, I would assume that you need to add the loss factor to those LISN port voltages also. I hope that you're not in a tight spot, because, except at the very lowest end of the measurement spectrum, the LISN port factor is essentially 0dB! The point gets kinda moot. Regards, Ed ------------------------ From: Patrick Lawler <[email protected]> Subject: CISPR11 conducted emissions: add the LISN attenuation? Date: Thu, 13 May 1999 17:32:18 GMT To: [email protected] Newsgroups: sci.engr.electrical.compliance > > When making CISPR11 conducted emissions measurements, should the measured > value > be adjusted to accommodate LISN attenuation? > Phrased another way, do the CISPR limits apply to the EUT port or the RF port? > > Normally, I'd add the attenuation factor to compensate, but the specification > calls out the limits _and_ the design of the LISN. Does this mean they > accommodated the LISN attenuation when the limits were set? > > -- > Patrick Lawler > [email protected] > > --------- > 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). > > > ---------------End of Original Message----------------- -------------------------- Ed Price [email protected] Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 List-Post: [email protected] Date: 05/13/1999 Time: 12:08:12 Military & Avionics EMC Services Our Specialty Also Environmental / Metrology / Reliability -------------------------- --------- 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).
