| In situ absorption coefficient |
 Posted: Thu Mar 08, 2012 1:42 pm |
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| kudzudav |
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| Joined: 21 Jul 2009 |
| Posts: 7 |
| Location: oxford, ms |
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| 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 |
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Last edited by kudzudav on Thu Mar 08, 2012 2:01 pm; edited 2 times in total
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dave |
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| Posted: Fri Mar 09, 2012 5:05 am |
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| Bruce |
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| Joined: 19 Apr 2005 |
| Posts: 460 |
| Location: Minneapolis, MN, USA |
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| Dave,
Have a look at my ASA Paper for some additional help. See pages 6-7.
Bruce |
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Last edited by Bruce on Tue Aug 09, 2022 2:45 pm; edited 1 time in total
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Best Regards,
Bruce C. Olson |
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| Posted: Fri Mar 09, 2012 4:17 pm |
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| kudzudav |
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| Joined: 21 Jul 2009 |
| Posts: 7 |
| Location: oxford, ms |
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| 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 |
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| Posted: Fri Mar 09, 2012 4:27 pm |
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| Bruce |
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| Joined: 19 Apr 2005 |
| Posts: 460 |
| Location: Minneapolis, MN, USA |
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| Probably Blackman, as that is the default. |
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Best Regards,
Bruce C. Olson |
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