Metroacúsica DS System
Metroacústica DS system uses software developed in LabVIEW language that remote control the Stanford Research Systems DS360 stand-alone generator.
The DS system offers proprietary software for calibration of the following equipment:
- old sound level meters - software "IEC60651ds.exe"
- new sound level meters - software "IEC61672ds.exe"
- sound exposure meters - software "IEC61252ds.exe"
- noise dosimeters - software "ANSI_S125ds.exe"
- measuring microphones - software "IEC61094ds.exe" (under development)
- band-pass filters - software "FiltersDS.exe"
With this generator and and some capacitive adapters it is possible to perform electroacoustic calibrations of sound level meters, noise dosimeters and sound exposure meters.
This generator is one of the most used equipment in the world to carry out electroacoustic calibrations. It is possible to generate all standard signals for calibration of sound level meters, noise dosimeters and sound exposure meters by pressing the keys on the panel of this equipment. The automation of the generation system can be performed when the demand for calibrations is large and it is necessary to perform quick calibration.
Every software is an executable application and for them o run correctly there must be used template spreadsheets. In these spreadsheets, some characteristics of the equipment to be calibrated, such as its measurement ranges and reference level, must be selected prior to the start of calibration.
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The guideline document DOQ-CGCRE-052 of the General Coordination of Accreditation (CGCRE) of the National Institute of Metrology (INMETRO), provides a list with the recommended minimum requirements to be checked when calibrating some electroacoustic equipment in Brazil.
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Software "IEC60651ds.exe" generates the standard signals for the following calibration tests of old sound level meters:
1. Linearity Level
2. Frequency Weighting (A, C and LIN)
3. Temporary Weights (Fast, Slow and Impulse)
4. RMS Detector
5. Time Average (LAeq) -IEC 60804 test
Software "IEC61672ds.exe" performs generation / measurement of the standard signals for the following calibration tests of new sound level meters:
1. Linearity level in the reference range
2. Linearity level including range control
3. Tone bursts response (Fast, Slow, SEL and LAeq)
4. Frequency weighting (A, C and Z)
5. Frequency and time weightings at 1 kHz
6. Overload indication
7. C-weighted peak level
8. Long-term stability
9. Stability at high level
10. Acoustic test with microphone attached
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Software "IEC61252ds.exe" generates the normalized signals for the following calibration tests of sound exposure meters:
1. Linearity level
2. A Frequency weighting
3. Response to of short-duration signals
4. Response to unipolar pulses
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Software "ANSI_S125ds.exe" generates the normalized signals for the following calibration tests of noise dosimeters:
1. Linearity Level
2. Frequency weighting (A, C and Lin)
3. RMS Detector - ANSI S1.4 Test
4. Time weighting (Fast and Slow) - ANSI S1.4 test
5. Time Average (LAvg)
6. DOSE (%) - Stationary Signal
7. DOSE (%) - Pulse Signal
Software "IEC61094ds.exe" is still under development and will carry out the measurement of the standard signals for the following calibration tests of measuring microphones:
1. Frequency response
2. Sensitivity
For the elaboration of the DS Metroacoustic System, the following documents were used as reference:
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Stanford DS360 Generator Manual.
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NBR ISO / IEC 17025: 2005 - General Requirements for Competence of Testing and Calibration Laboratories.
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IEC 60651: 1979 - "Electroacoustics - Sound Level Meters".
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IEC 60804: 1985 - "Electroacoustics - Integrating-averaging Sound Level Meters".
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IEC 60942: 2003 - "Sound Calibrators".
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IEC 61672-1: 2013 - Sound level meters - Specifications
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IEC 61672-3: 2013 - Sound level meters - Periodic tests
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IEC 61252: 1993 - Sound Exposure Meters
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ANSI S1.25: 1991 - "Specification for personal noise dosemeters".
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ANSI S1.4: 1983 - "Specification for sound level meters".
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Guide for the expression of measurement uncertainty - GUM, 2003, Third edition in Portuguese language.
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VIM International Vocabulary of Metrology - Fundamental and General Concepts and Associated Terms, 1st edition Luso-Brazilian, 2012
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DOQ-CGCRE-052 - Guidance for calibration of acoustic measurement devices.