B&K 2250 Light Manuel d'utilisateur Page 17
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Noté. / 5. Basé sur avis des utilisateurs
Hand-held Analyzer Type 2250 –
Instruction Manual
12
• y is F for Fast-weighted, S for Slow-weighted or I for Impulse-weighted
• T is the start time of the measurement, indicated as Start Time
•
∆t is the measuring period, indicated as Elapsed Time
The minimum time-weighted sound level is expressed in decibels (dB).
The symbols used on the screen of Type 2250 for maximum time-weighted sound levels are (for A, C
and Z frequency-weighting and F, S and I time-weighting):
L
AFmin
, L
ASmin
, L
AImin
, L
CFmin
, L
CSmin
, L
CImin
, L
ZFmin
, L
ZSmin
, L
ZImin
Equivalent Continuous Sound Level
The equivalent continuous sound level (also called time-average sound level), L
xeq
(T), is defined as
twenty times the logarithm to base ten of the ratio of a root-mean-square sound pressure during a time
interval to the reference sound pressure, sound pressure being obtained with a frequency weighting, x.
The time interval is starting at t = T and ending at t = T +
∆t where:
• x is A for A-weighted, C for C-weighted or Z for Z-weighted
• T is the start time of the measurement, indicated as Start Time
•
∆t is the averaging time interval, indicated as Elapsed Time
The equivalent continuous sound level is expressed in decibels (dB).
In symbols, equivalent continuous sound level, L
xeq
(T), is given by:
where:
• ξ is a dummy variable of time integration over the averaging time interval
• p
x
(ξ) is the x frequency-weighted instantaneous sound pressure
• p
0
is the reference sound pressure, equal to 20 µPa
The symbols used on the screen of Type 2250 for equivalent continuous sound levels are (for A, C and
Z frequency-weighting):
L
Aeq
, L
Ceq
, L
Zeq
Equivalent Continuous I-weighted Sound Level
The equivalent continuous I-weighted sound level (also called average I-weighted sound level),
L
xIeq
(T), is defined as ten times the logarithm to base ten of the mean of ten to the power of the I time-
weighted sound level, L
xI
(t), divided by ten during a time interval. The time interval is starting at t = T
and ending at t = T +
∆t where:
• x is A for A-weighted, C for C-weighted or Z for Z-weighted
• T is the start time of the measurement, indicated as Start Time
•
∆t is the averaging time interval, indicated as Elapsed Time
The equivalent continuous I-weighted sound level is expressed in decibels (dB).
In symbols, equivalent continuous I-weighted sound level, L
xIeq
(T), is given by:
where:
• ξ is a dummy variable of time integration over the averaging time interval
L
xeq
T() 20lg 1 ∆t⁄() p
x
2
T
T ∆t+
∫
ξ()dξ p
0
⁄ [dB]=
L
xIeq
T() 10lg 1 ∆t⁄() 10
L
xI
ξ()10⁄
T
T ∆t+
∫
dξ [dB]=
BE171211.book Page 12 Thursday, May 27, 2004 1:01 PM
- Technical 1
- Documentation 1
- Hand-held Analyzer Type 2250 2
- Safety Considerations 3
- Table of Contents 4
- Chapter 1 6
- 1.2 System Overview 7
- 1.3 Hardware Setup 8
- CHAPTER 1 10
- Chapter 2 12
- 2.4 Frequency Weightings 13
- 2.5 Measured Quantities 13
- Table 2.1 14
- Frequency weight 14
- IEC 61672 – 1, Ta 14
- Table 2.2 15
- Exponential time 15
- CHAPTER 2 16
- ∆t where: 17
- 2.5.4 Spectrum Measurements 18
- Chapter 3 20
- 3.6 EMC test procedures 21
- 3.6.4 Accessories 22
- Chapter 4 24
- 4.5 Microphone 25
- 4.6 Frequency Response 25
- CHAPTER 4 26
- 4.6.3 Low-frequency Responses 27
- 4.7 Directional Response 31
- Table A.25 35
- Table A.32 37
- Table A.34 to Table A.36 39
- Table A.44 to Table A.46 42
- 4.8 Self-generated Noise 44
- 4.9 Measuring Range 46
- 4.9.4 Indicator Range 47
- 4.9.5 Linearity Range 47
- 4.9.6 Pulse Range 47
- 4.9.7 Linear Operating Range 47
- 4.10 Detectors 48
- 4.10.2 Linear Averaging 49
- 4.10.3 Peak 49
- 4.11 Spectrum Analysis 50
- 4.11.3 Linear Operating Range 51
- 4.11.4 Measurement Range 52
- Fig.4.31 53
- The most sensitive 53
- Table 4.13 53
- Magnetic Fields 53
- 4.13.2 Trigger Socket 54
- 4.14.1 Output Socket 54
- 4.14.2 Headphones Socket 54
- 4.15 Power Supply 55
- 4.16 Warm-up Time 55
- 4.17 Real-time Clock 55
- Appendix A 58
- angle of incidence to 65
- ‘UA 1404’ 69
- A.4 Directional Responses 71
- APPENDIX A 100
- Instruction Manual 101
- 500 Hz – 3550 Hz 105
- 4000 Hz – 10600 Hz 106
- 11200 Hz – 20000 Hz 107
- Appendix B 110
- APPENDIX B 112
- B.3 Irrelevant Topics 116
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