OBSI Module Real-Time On Board Sound Intensity measurement & post-processing software User Guide – V1.1 Soft dB Inc. 1040, Belvedere Avenue, Suite 215 Quebec (Quebec) Canada G1S 3G3 Toll free: 1-866-686-0993 (USA and Canada) E-mail: contact@softdb.
CONTENTS 1 Introduction ............................................................................................................................... 1 2 System Description ................................................................................................................... 3 2.1 OBSI Setup ........................................................................................................................................................... 3 2.2 Connections ..............................
1 Introduction Congratulations on your purchase of the OBSI Module. The OBSI Module is a powerful tool to perform tire-pavement noise according to AASHTO TP 76-10 standard method. This software combines the measurement and post-processing tools to produce high quality results. The OBSI Module is intended to run on an I-Track System, but can also be used with an Alto-6 using a stand alone computer. The software can also be installed on a stand alone computer to use the post-processing tools.
2 System Description This user guide covers only the software part of the measurement system as the sensors and the fixture are not supplied with the software. For more information about relevant sensors, please contact Soft dB at contact@softdb.com. For the purpose of this user guide, the I-Track system will be used as the base system. A dual ICP probe and ICP tachometer will also be used.
General OBSI Setup - Probe position Leading and trailing probes must be placed 4.125” from the center of the wheel hub Mic B Mic A 5/8” - 16 mm 3” - 76 mm 4” - 102 mm The current OBSI standard specifies use of an ASTM F2493 Standard Reference Test Tire (SRTT) (P225/60R16) available from Michelin. A purchasing procedure is detailed in appendix.
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3 Quick Start Step 1 Start up 1) Turn on the laptop by pressing the power button. 2) Once Windows® started, launch the OBSI software from the start menu. Step 2 1) Connexions Connect the microphones to the DSP input connectors using appropriate cabling: Right Side • • • • • • Channel 1: Channel 2: Channel 3: Channel 4: Channel 5: Channel 6: Leave unconnected, Tachometer, Leading Edge Probe – Mic A, Leading Edge Probe – Mic B, Trailing Edge Probe – Mic A, Trailing Edge Probe – Mic B.
Step 3 1) Launch the measurement Launch the measurement by clicking the RUN button: RUN button 2) Run the measurement for a while and stop it by pressing the STOP button: STOP button 3) Save the measurement by clicking on the blinking record warning or with ctrl+s.
4 Software Description 4.1 Main Interface The main interface is used for both performing a measurement and post-processing. Main Interface Measure Controls Main Time Axis File Info Rescale Axis Legend Display Settings Audio Controls Display Area 4.1.1 Measure Controls The measure controls are related to the acquisition behavior. The top indicator shows the elapsed time when measuring. The RUN/LOG/STOP button controls the measurement. Two modes are available: • • Log on start; View before log.
The auto-stop duration defines a logging maximum duration. When this duration is reached, the logging process is automatically stopped. This duration can range from 1 s to 60 minutes. 4.1.1.1 Log On Start When using this mode, the measurement starts with logging when pressing the RUN button. The RUN button then becomes the STOP button. The measurement is stopped when the user clicks this button or when the auto-stop duration is reached. To select this option, uncheck the “View Before Log” checkbox. 4.1.1.
The bottom left slider applies an additional gain to the operating system volume control and the bottom right vertical scales represent the audio dynamic ranges. 4.1.4 Main Time Axis The main time axis represents the whole measurement time range. Two cursors allow the selection of a certain portion of the measurement to perform averaging and a third cursor represents the current audio position during audio playback.
4.1.5 Display Area, Legend, display Settings and Rescale Axis The display area can be one of the following displays: • • • • Time history graph, 1/3 octave band graph, FFT graph, Numeric indicators. The graph type and the data to be displayed are selected in the display setup interface. This interface can be launched using the Display Settings button. The legend on the top of each display area identifies the plot and displays the global level. 4.
4.2.1 Sensor Selection The sensor selection radio buttons allow the selection of the Leading Edge Probe, the Trailing Edge Probe or the Tachometer. The input setup interface will behave according to this control state. 4.2.2 4.2.2.
4.3 Record Setup The record setup describes the software behaviour when it comes to record measurement files. To launch this interface, go to Setup/ Record Setup. Record Setup Interface The automatic save checkbox allows to automatically save a measurement file at the end of the measurement process otherwise the measurement needs to be manually saved using File/save or ctrl+s or clicking on the blinking record warning visible on the main interface at the end of an unsaved measurement.
4.5 Main Display Setup The main Display Setup controls how the software will display the results. To launch this interface, go to Setup / Display setup. 4.5.1 Display Setup Tab The display setup tab allows to edit the main interface appearance. The number of display areas can be defined and their individual display setups can be defined in the Display Area Setup interface by clicking on the gear icon of each display. 4.5.1.
Each graph can display up to 4 plots which can be of two different types, intensity and pressure or coherence and PI index for example.
4.5.2 Main Historic Tab The main historic tab allows to define the data contained in the main time history. The main time history graph is a useful tool when it comes to define the time boundaries to a specific portion of the measurement. For example, the following figure illustrates the speed in miles/h in the main time history graph.
Main Time History Graph (selected = Speed (miles/h)) 4.5.3 Plot Colors Tab The plot colors tab allows to define the plot colors. The positive and negative colors are used to specify the direction of the intensity vector. For all other data, the positive color is used.
4.6 Data Export The data can be exported as a tab delimited file that can be opened with any spreadsheet software. The data contained in this file are the data displayed on the main interface graph. To get a specific dataset in the exported data, it needs to be displayed in its appropriate form on the main interface. For example, if the 1/3 octave sound intensity and sound pressure time history is displayed on the main interface, these dataset will be exported in the output file.
Appendix 1 Standard Reference Test Tire (SRTT) Purchasing Procedure 20
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