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AFMG Network Forum Index -> AFMG EASERA -> In situ absorption coefficient    View previous topic :: View next topic  In situ absorption coefficient Posted: Thu Mar 08, 2012 1:42 pm kudzudav Member   Joined: 21 Jul 2009 Posts: 7 Location: oxford, ms EASERA users I have managed the procedure to find the "reflection factor" in dB via the procedure in the EASERA manual. My difficulty is in converting this to a absorption coefficient- I am familiar with the impedance method, and there is some interesting information in Robinson and Xiang, "On the subtraction method for in-situ reflection and diffusion coefficient measurements", but I am at a loss looking at the statement, "More sensible is the representation of the reflection factor r in octaves or third octaves, because with these such errors are smoothed out. The absorption coefficient can be calculated by means of the formula alpha = 1 - |r^2|." i.e. alpha = 1-|(-10dB)^2|= -99 any suggestions? I assume I have missed something here. thanks Dave Last edited by kudzudav on Thu Mar 08, 2012 2:01 pm; edited 2 times in total _________________ dave Posted: Fri Mar 09, 2012 5:05 am Bruce Member   Joined: 19 Apr 2005 Posts: 460 Location: Minneapolis, MN, USA Dave, Have a look at my ASA Paper for some additional help. See pages 6-7. Bruce Last edited by Bruce on Tue Aug 09, 2022 2:45 pm; edited 1 time in total _________________ Best Regards, Bruce C. Olson Posted: Fri Mar 09, 2012 4:17 pm kudzudav Member   Joined: 21 Jul 2009 Posts: 7 Location: oxford, ms thank you Bruce Is there a specific window function that is used? I was trying to chop off the data without a function but I was unclear on windowing without processing _________________ dave Posted: Fri Mar 09, 2012 4:27 pm Bruce Member   Joined: 19 Apr 2005 Posts: 460 Location: Minneapolis, MN, USA Probably Blackman, as that is the default. _________________ Best Regards, Bruce C. Olson AFMG Network Forum Index -> AFMG EASERA You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum All times are GMT   Page 1 of 1   All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First  Select a forum General----------------Board RulesForum Announcements Software Forums----------------EASE 5EASE 4EASE EvacAFMG EASERAAFMG SysTuneAFMG SoundFlowAFMG ReflexEASE FocusEASE AddressSDK for GLL PLug-in API   Powered by phpBB © 2001-2003 phpBB Group Theme created by Vjacheslav Trushkin Variation by CodeWeavers and AFMG