B&K 2250 Light Manuel d'utilisateur télécharger pdf (Page 12)

Chapter 2

Measured Quantities and Parameters

2.1 Introduction

This chapter contains detailed information on the measured quantities and parameters that Type 2250 is

capable of measuring.

2.2 Measuring Low-level Sounds

If the measured sound level is within the Linear Operating Range or, for C-weighted peak sound levels,

within the Peak C Range given in the specifications (see section 4.9.7 and section 4.9.8), then the

inherent (self-generated) noise and level linearity problems can be ignored.

It is possible to correct the measured sound levels, except peak levels, for the typical inherent noise,

found in the specifications, see section 4.8.2. The correction for inherent noise can be made by sub-

tracting inherent noise, L

inh

, from the total sound level, L

tot

, using the following equation:

If L

tot

– L

inh

is less than 3 dB, the sound level is too low to be compensated.

Fig.2.1

Error from inherent

noise

Fig.2.1 shows the error on the measured sound levels from the presence of inherent noise. The curve

can also be used for compensation by subtracting the error from the measured sound levels. This is

equivalent to using the formula.

res

10lg 10

tot

10⁄

inh

10⁄

⎠

⎞

–

⎝

⎛

tot

- L

inh

[dB]

Error (dB)

BE171211.book Page 7 Thursday, May 27, 2004 1:01 PM

1 2 ... 7 8 9 10 11 12 13 14 15 16 17 ... 121 122

Commentaires sur ces manuels

Pas de commentaire

B&K 2250 Light Manuel d'utilisateur Page 12

Commentaires sur ces manuels