The high floor noise in the low frequency area could simply be due to your receiver. Try running the test without the LISN connected (terminate the receiver with a 50 ohm load) and check the performance of the receiver. I have seen many spectrum analyzers act this way.
Regards, Randy Flinders EMC Engineer Emulex Network Systems (714) 513-8012 [email protected] ---------- From: [email protected] Sent: Tuesday, November 17, 1998 7:53 PM To: [email protected] Subject: suspect conducted emissions Hello group, I recently carried out a conducted emission in our unlined screen room with no EUT connected. I.e just the LISN inside and measuring receiver outside the room. I was expecting the plot to be a horizontal line and very low perhaps in the region of 10 or 20dB. Instead I noticed that the plot starts at about 40dB at 150kHzand decreases to about 20dB at around 1MHz and then after that is a horizontal line all the way to 30MHz. Bearing in mind that the room is very well grounded and I use a reputable measuring device. My questions are: 1-Is this what one would expect to see? 2-Why the noise floor so high in an screen room? 3-What can we do to reduce the noise floor? 4-What is the best method to ensure that the room is O.K? Any help and advice is appreciated. With regards Peter E-mail: [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). --------- 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).
