TSI Quest EDGE EG-4P, Руководство пользователя

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B-1
A P P E N D I X B
Glossary of Terms
Background Noise,
effects of Background noise can cause considerable error in measurement when its level is
high relative to the level of a noise source of interest. If you can make
measurements both with and without the contribution of a noise source of interest,
you can mathematically subtract the background noise from the combined
measurement, yielding the level of the noise source of interest alone. The
accuracy of this determination improves as the difference between the two
measurements increases.
To remove background noise
1. Obtain a measurement that includes the contribution of the noise source of
interest (the combined measurement).
2. Make a second measurement under exactly the same conditions as in Step 1
but without the presence of the noise source of interest (the background noise
measurement).
3. Determine the decibel difference between these two measurements.
4. Find that difference on the x -axis of the figure below.
5. Find the point on the curve directly above this difference.
6. Read the corresponding value on the y-axis for that point (the correction
value).
7. Subtract the correction value from the combined measurement.
Example : Measurements with and without the noise source of interest are 91 dB
and 90 dB, respectively. For a difference of 1 dB, the background noise correction
value is 7 dB. Therefore, the level for the noise source of interest without the noisy
background is 84 dB.