power determination of outdoor vehicles requires 6 measuring points spread on
a semispherical surface. The SCS9004 system is well suited for this application
and, in addition, it is also capable of measuring the ear driver LeqA and recording
the RPM (or speed, position) of the vehicle. The RPM and the LeqA are wireless
transmitted to the SCS9004 PC controller, allowing the maximum freedom and easiest
way of performing the application.
The 2000/14/CE Directive
Acoustic power determination of outdoor vehicles requires 6 measuring points spread on a semispherical surface. The SCS9004 system is well suited for this application and, in addition, it is also capable of measuring the ear driver LeqA and recording the RPM (or speed, position) of the vehicle. The RPM and the LeqA are wireless transmitted to the SCS9004 PC controller, allowing the maximum freedom and easiest way of performing the application.
The SCS 9004 “DSPlus”
The ISO Standard series 374x requirements is to perform the Acoustic Power determination of LWA in 1/1 or 1/3 octave bands using a minimum of 9 measurement points distributed around the noise source to be certified. If special rooms are not available, which is the case for most practical situation, the code of practice is to apply the ISO 3744 procedure and perform an acoustical testing of the environment by measuring the reverberation time, in order to calculate correction factors for the measurements. More recently introduced standards, as an example for house appliance machineries, also requires to document the time history of the overall level and/or the level of the specific frequency band in specific working conditions. Factors like the stationarity of the noise emitted and the working time of the machine cycle, impose the choice between scanning and parallel measurements. Applying the ISO standard is not an easy job sometimes and it is absolutely necessary to have reliable instruments available, also dedicated to the specific application of determining the Acoustic Power of a noise source. Some important aspects can be the precision, ease-of-use, transportability, low power consumption and a specific software able to give the results straightforward in a standardized format. All characteristics above have been taken into consideration for the development of the SCS 9004 system which may be considered as the “state of art” with respect to the features/price ratio, probably one of the highest ratios available today, both for the scan and for the DSPlus versions.
The SCS 9004 “scan”
Virtually any Real Time sound analyzer can be connected to the MESA MUX10A Multiplexer to form a powerful system for Acoustic Power determination. The MESA MUX10A is compatible with a wide choice of transducers and data acquisition systems and has a feature of an extremely high input dynamic and frequency range, high precision and outputs stability, manual and remote (RS-232) programming.
The SCS 9004 Software
The SCS 8400 software system is a “state of the art” for easy and precise Acoustic Power determination supporting all relevant standards and market available hardware platforms.
The SCS 8411 software calculates the Sound Power level according to ISO 3744, ISO 3745 and to directive 2000/14/CE (dedicated to grass cutter machine). The European (EU) directive 2000/14/CE is a part of ISO 3746. ISO 7779 is also supported (except multiple tone search, impulse index detect and the measurement of sound pressure level at defined operator and bystander position).
The PC software has an unique user interface and it allows the user to graphically select the measurements positions, inputs the surface and other fixed parameters, performs autorange and checks for overloads. Data are transferred to the PC through high speed link where the software performs all necessary calculation for linear averaging, corrections and LWA.
The resulting power spectrum is displayed fully annotated while intermediate spectra are available as an ASCII file for user purposes or to trace time histories on each frequency band as requested by most recent standards. A wizard is also provided which guides the user step by step through all test setup, including calibration and machine identification in the internal data base.
Main characteristics of the system
Type 1, IEC/EN standards complies with 374x, 639x, 7779, 2000/14/CE and
Instrumented front-end for microphones and ICP transducers
Selectable gain and weighting filters with autorange and overload detection
Up to 12 channels in a single rack for serial and parallel measurements
Reverberation Time measurement and keyed-in parameters correction
Real Time 1/1 and 1/3 octave bands for measurement of dynamic
Leq measurement, frequency weighting A, C, Lin, dynamic range > 80dB
PC software in Windows, ASCII data export