Hi Mark, If you understand the fact that adding two sources of the same level gives you a 3dB increase, you can do some quick addition.
Let's say one of your small chassis has a noise level of 75dB. If you add a second one you would get a total noise level of 78dB. (Of course this does not consider cancellation due to superposition, but at least this is a worst case scenario.) If you add another pair of chassis (i.e. total of four), you get to 81 dB. And so on and so on... When the noise levels are different, then it becomes a little more difficult. Without going into great detail here, you should add 13dB to the level of a single chassis to get the noise level for 20 chassis... Hope this helps... Paul Hare From: [email protected] [mailto:[email protected]]On Behalf Of Gandler, Mark Sent: Tuesday, January 21, 2003 6:31 PM To: [email protected] Subject: Acoustic noise calculations for multiple shelves Hello Group! Imagine you are going to install 20 small chassis (shelves) in one rack in Central Office. If you know your acoustic noise level from one chassis, is it any way to calculate total noise? Sorry, if it is not the smartest question. Please reply!!! Need an answer!!! Thanks, Mark Gandler Ciena 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: Ron Pickard: [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: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" 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: Ron Pickard: [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: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
