Soft dB OBSI User Manual

Soft dB Inc.
1040,
Quebec (Quebec) Canada G1S 3G3
Toll free: 1
E-mail: [e-mail]

OBSI Module

Real-Time On Board Sound Intensity
measurement & post-processing software

User Guide – V1.1

Belvedere Avenue, Suite 215

-866-686-0993 (USA and Canada)

CONTENTS

1 Introduction ............................................................................................................................... 1

2 System Description ................................................................................................................... 3

2.1 OBSI Setup ........................................................................................................................................................... 3

2.2 Connections ........................................................................................................................................................ 5

3 Quick Start ................................................................................................................................. 7

4 Software Description ................................................................................................................ 9

4.1 Main Interface ..................................................................................................................................................... 9

4.1.1 Measure Controls .................................................................................................................................... 9

4.1.2 File Info ...................................................................................................................................................... 10

4.1.3 Audio Controls ....................................................................................................................................... 10

4.1.4 Main Time Axis ....................................................................................................................................... 11

4.1.5 Display Area, Legend, display Settings and Rescale Axis ........................................................ 12

4.2 Input Setup ........................................................................................................................................................ 12

4.2.1 Sensor Selection .................................................................................................................................... 13

4.2.2 Sensor Setup ........................................................................................................................................... 13

4.3 Record Setup .................................................................................................................................................... 14

4.4 Computing Setup ............................................................................................................................................ 14

4.5 Main Display Setup ......................................................................................................................................... 15

4.5.1 Display Setup Tab ................................................................................................................................. 15

4.5.2 Main Historic Tab ................................................................................................................................... 17

4.5.3 Plot Colors Tab ....................................................................................................................................... 18

4.6 Data Export ........................................................................................................................................................ 19

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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.

General Specifications

• Sound Intensity

• Sound Pressure

• Coherence

Measurement Types

• PI Index

• Audio signals

• Vehicle speed

• Vehicle traveled distance

Display Types

• 1/3 Octave band

• FFT

• Time History

• Numerical indicators

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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 [e-mail].

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. A special version of the I-Track system with higher
input ranges is available as an option; please contact Soft dB at [e-mail] for more
information.

2.1 OBSI Setup

General OBSI Setup – Dual-Probe Vertical with Tachometer

Wheel

Assembly

Trailing Edge

Sound Intensity

Probe

Tachometer

Leading Edge

Sound Intensity

Probe

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General OBSI Setup - Probe position

Leading and trailing
probes must be placed

4.125” from the center
of the wheel hub

Mic A Mic B

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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2.2 Connections

Right Side Back Left Side

Power Headphones Sensors

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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 Connexions

1) Connect the microphones to the DSP input connectors using appropriate cabling:

Right Side

• Channel 1: Leave unconnected,

• Channel 2: Tachometer,

• Channel 3: Leading Edge Probe – Mic A,

• Channel 4: Leading Edge Probe – Mic B,

• Channel 5: Trailing Edge Probe – Mic A,

• Channel 6: Trailing Edge Probe – Mic B.

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Step 3 Launch the measurement

1) 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.

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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.

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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.

4.1.1.2 View Before Log

When using this mode, the measurement starts without logging when pressing the RUN button.
The RUN button then becomes the LOG button. When pressing the LOG button, the measurement
is reset with logging effective. The LOG 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, check the “View Before Log” checkbox.

4.1.2 File Info

The file info cluster contains the basic information about a measurement file such as:

• File name,

• Recording date,

• Active sensors,

• Comment.

When a measurement file is loaded, this information is updated. When a measurement starts, this
information is also updated with the current settings.

Clicking on the pencil icon on the comment field will launch the File Info interface allowing to edit
the comment. Once the comment has been edited, the measurement file needs to be saved to
record the changes.

4.1.3 Audio Controls

The audio controls allow to listen to the audio streams during a measurement or on a
measurement file. The PLAY/PAUSE button starts or stops the audio playback of a recorded
measurement file.

The source selection radio buttons links the selected sensor to the audio channel. For example, the
right channel could be linked to the mic A from the leading probe and the left channel to mic B.

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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.

Clicking on the graph button on the right side of this axis displays the main time history which
shows a time history of a selected data source, such as averaged sound intensity or vehicle speed.
The source data can be selected from several choices on the Display Setup interface (4.5.2).

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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.

4.2 Input Setup

The Input setup is used prior to perform a measurement and is used to calibrate the sensors. To
launch this interface, go to Setup/Input Setup.

Input Setup Interface

Sensor Setup

Sensor

Selection

Calibration

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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 Sensor Setup

4.2.2.1 Intensity probes

The intensity probes setup includes all the relevant information such as:

• Probe enabled state

• Mic A and B input Setup:

• Input channel,

• Input range (when available),

• Input type (AC, DC or ICP),

• Input sensitivity

• Amplitude calibration date.

• Microphone spacing (OBSI standard = 16 mm)

• Phase correction enabled state and phase calibration date.

To perform sensor calibration (amplitude or phase), click on the calibrate button to launch the
calibration interface.

4.2.2.2 Tachometer

The tachometer setup includes all the relevant information such as:

• Tachometer enabled state

• Tachometer input Setup:

• Input channel,

• Input range (when available),

• Input type (AC, DC or ICP),

• Input sensitivity.

• Schmitt Trigger thresholds;

• Wheel diameter and calibration date;

• Number of ticks per rotation.

To perform a calibration of the wheel diameter, click on the calibrate button to launch the
calibration interface.

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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.

The measurement files will be recorded in the record folder. The default directory is located at My
documents/OBSI/.

The prefix allows the user to specify a string of characters at the beginning of the file name. The
prefix can be the current date or a custom one. The measurement files will be automatically
incremented from 000 to 999. A common file name will have the following format:
“Prefix_001.obsi”.

The “Load files using saved settings” check box will load a measurement file and restore the display
settings and the computing settings to the way they were at the moment the measurement was
saved. Leave this checkbox unchecked when you want to load measurement files using the current
display settings and computing settings.

4.4 Computing Setup

The computing setup allow to set the spectrum range (OBSI standard = 400 Hz to 5 kHz) and the
temperature. These computing settings do not need to be set prior to measurement and can be
changed. Any change to this interface will be automatically applied to the current measurement
file.

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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.

4.5.1.1 Display Area Setup Interface

The display area setup interface defines the display type and data type of a specific display area.

The available display types are:

• Time history graph,

• 1/3 octave spectrum graph

• FFT spectrum graph

• Numerical indicator

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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. The available data are:

• Intensity (dB, dBA, W/m² or W/m²(A)) – (Instantaneous or Time averaged)

• Leading edge probe

• Trailing edge probe

• Average leading edge / trailing edge

• Pressure (dB, dBA, Pa²(rms²) or Pa²(rms²)(A)) – (Instantaneous or Time averaged)

• Leading edge probe (mic A)

• Leading edge probe (mic B)

• Leading edge probe (average mic A / mic B)

• Trailing edge probe (mic A)

• Trailing edge probe (mic B)

• Trailing edge probe (average mic A / mic B)

• Average leading edge / trailing edge

• PI Index (dB, or linear) – (Instantaneous or Time averaged)

• Leading edge probe

• Trailing edge probe

• Coherence (dB, or linear) – (Instantaneous or Time averaged)

• Leading edge probe

• Trailing edge probe

• Speed (m/s, km/h, mile/h or ft/s) – (Instantaneous or Time averaged)

• Distance (m, km, mile or ft) – (Instantaneous or Time averaged)

Several presets are available from the top radio buttons:

• Intensity,

• Pressure,

• PI Index,

• Coherence,

• PI Index/ Coherence,

• Speed,

• Distance.

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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.
And the main time axis boundaries are then adjusted to the measurement portion where the speed
was stable at 60 miles/h (OBSI standard) and perform averaging on this specific portion of the
measurement.

Once the measurement time boundaries are set, the measurement region of interest can be saved
using File/Save selection as.

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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.

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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.

Two export functions are available. The first is “Export Current” which exports the currently loaded
file and the second is “Export Multiple” which allows exporting several files to a single output file.

To export data, go to File/Export.

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Appendix 1 Standard Reference Test Tire (SRTT) Purchasing Procedure

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