9.11.2009 1 Transmissions, Gearboxes and Axles RotasPro Noise Analysis.

9.11.2009 1

Transmissions, Gearboxes and Axles

RotasPro Noise Analysis

9.11.2009 2

The company was founded in 1985. It is situated in Göttingen in the heart of Germany. Since 1989 the main product are measurement system for the acoustical quality analysis. There are 20 employees and more than 500 test systems deployed.

Base system are ROTAS and MESAM-4 (a joint development with DaimlerChrysler). Build on top of them are APAS for the cabin noise analysis, ROTAS-GP for the analysis of gearboxes and transmissions, ROTAS-ZP for the gear test, ROTAS-TMO for the test of tapered roller bearings.

MESAM 4

APAS-II

Base System Gearboxes and ComponentsCabin noise

ROTAS-Mobil

Discom Industrial Measurement Inc.

9.11.2009 3

ZF DGear Testers 4 Systems

Volkswagen D, ES, SA,AR, China,B,SK,BR

Gearboxes, Transmissions, Gear Testers, Cabin Noise Production Database, 178 Systems

Tongil, Korea

Axles, Durability test Stand, 1 System

SFT, Magna Stey Powertrain

Axles and gearboxes 28 Systems

Skoda, Cz

Gearboxes, 7 Systems

SAIC Shanghai Automobile Internatiol Corp.

Gearboxes test systems, 5 Systems

SKF D, USA, India, Ukraine

Tapered Roller Bearings, 35 Systems

Robert Bosch Starters, injection pumps, production database 6 Systems

Renault, PeugeotTransmissions, Gear Testers 11 Systems

GM, USA, Opel D and AGearboxes and Axle Testers, Gear Testers 44 Systems

Jatco, Japan

CVT Transmissions

Discom: Customers and Applications

Fiat, Iveco, Tata, It, Brazil, India

Manual Transmissions 20 Systems

Getrag, USA Sc, Single Flank Gear Tester for Cummins Engine Gears with Tors. Acceleration

Graziano, Italy Gearboxes and Axles for Audi, Aston Martin, Ferrari, Lamborghini, Maserrati

Eaton, Br Manual transmissions,

mobil system

Ford, D

Gear Testers 4 Systems

First Automobile Works, China

Gearboxes 2 Systems

DaimlerChrysler D, US Cooperation MESAM4, gearboxes, transmissions and engines. 48 Systems

Borg-Warner, USA,UK Transmissions und Axles 11 Systems

Bentley, UK

Cabin Noise Analysis APAS, 2 Systems

American Axle, USA

Front and Rear Axles, 5 Systems

Hyundai, Korea

Gear tester 2 Systems

Cummins

9.11.2009 4

Rotas NVH Testing

End of line test with vehicle correlation and the ability to find production errors

Separation of noise components from inner wheels of transmissions

Calibrated evaluation for comparison of the production process with car experiences

Simultaneous measurement and evaluation of all transmission order components

Recognition of nicks on gears and bearings

Trainable system in combination with fixed limits

Test results stored in central data base

Intranet evaluation of test results for groups of test benches

9.11.2009 5

Parameter- und Limit Database

Parameter- und Limit Database

RotasAnalysisProgram

RotasAnalysisProgram

Result DatabaseArchives, SQL-DBResult Database

Archives, SQL-DB

Web StatisticsWeb StatisticsPresentationPresentation

Test StandControl

Test StandControl

Sensors

ROTAS Test Stand Configuration

9.11.2009 6

Rotas Analyzers

19”-Industrial PC.TAS Frontend RAID systemDual Core and I7 CPUs

Panel with IPC and TASFrontend. AC and UPS buildinto panel

TAS USB Measurement frontend.10 analog channels, 4 speed inputs, D/A monitor outputs.Mobile system with USB power for 5 ICP sensors

9.11.2009 7

BKS03 Accelerometer

1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 k Hz

-20.0

-15.0

-10.0

-5.0

0.0

dBg

TrnsFnc

The BKS03 has a linear frequency range of up to 10 kHz and can be used to pick up the NVH signal also from unfinished surfaces

9.11.2009 8

RotasPro separates the noise into the different sources inside the transmission like input, intermediate and output shaft. I addition, the the total noise is evaluated.

A prominent method is the calculation of the spectral components of the noise. The spectrum shows the characteristic of the noise in form of a curve.

For transmissions, spectral components exist for tooth mesh and its harmonics.

The spectra are compared with limit curves. If the limit curve is exceeded, a defect can be assumed.

In addition, temporal measurement give Crest, Peak and RMS values, which are used for the identification of nicks on the transmission parts.

Noise sources

A main noise source is the tooth mesh of the gears.

Analysis of transmission noise

9.11.2009 9

Input

One rev

Exact order analysis is accomplished by generating of the same amount of samples per revolution of a part, independent of its revolutionary speed.

Digital resampling allows for the processing of 3 to 5 shafts of a transmission.

From this resampled time domain signal, spectra evaluation produces order components. These are the amplitudes of sine components, which are cyclic with the revolution of the part

Order Analysis

Input

One rev

Input

One rev

Constant numberof samples perrevolution

9.11.2009 10

Revolution Synchronous Transmission Analysis

Input Shaft Interm. Shaft Output Shaft

The transmission noise is the sum of the noise originating from the individual mechanical components.

For the gear noise components, the individual sources can be isolated by the transmission ratio.

Synchronousorder analysis:The signals are acquired synchronousto the inner shafts.AcousticalStroboscope

Input Shaft

Interm. Shaft

Output Shaft

9.11.2009 11

Signal

Background

Average:Signal enhanced

For every shaft, averaging is performed synchronous to its revolution.

Signal components of the synchronous shaft are enhanced, other noise components are attenuated.

One shaft is shown. Rotas can do the processing for 3 to 5 shafts simultaneously.

Usually, only one sensor is needed.

The synchronization can be done for inner shafts, for which only the transmission ration is known.

Synchronous Averaging I

Signal

Background

Signal

Background

+

+

+

+

+

Summe * 1/n =

9.11.2009 12

400 800 1200160020002400280032003600m Rev

-16.0

-8.0

0.0

8.0

16.0

g

ZwAn

-16.0

-8.0

0.0

8.0

16.0

g

ZwAb

-16.0

-8.0

0.0

8.0

16.0

g

TsAb

400 800 1200160020002400280032003600m Rev

-16.0

-8.0

0.0

8.0

16.0

g

ZwAn

-16.0

-8.0

0.0

8.0

16.0

g

ZwAb

-16.0

-8.0

0.0

8.0

16.0

g

TsAb

Synchronous Averaging II

Nicks are shown in the synchronous channel that is synched with the offending shaft.The nick detection is based on the Crest value

Crest = Peak value/RMS value

AG4 V4.0 Typ 39 Unit 67 04.Jun'2000,17:10:16-------------------------------------------------------------------Code Description Gear Is Lim Av Unit Kx 448 NICK 3.-Gear / Up 3-Z 16.8/ 12.0/ 9.5 Crest ZwAn--------------------------------------------------------------------


9.11.2009 13

400 800 1200160020002400280032003600m Rev

-16.0

-8.0

0.0

8.0

16.0

g

ZwAn

-16.0

-8.0

0.0

8.0

16.0

g

ZwAb

-16.0

-8.0

0.0

8.0

16.0

g

TsAb

400 800 1200160020002400280032003600m Rev

-16.0

-8.0

0.0

8.0

16.0

g

ZwAn

-16.0

-8.0

0.0

8.0

16.0

g

ZwAb

-16.0

-8.0

0.0

8.0

16.0

g

TsAb

Time Domain Measurements

Peak: The maximum amplitude in a time domain signal. In the example to the right the Peak value is about 15 g

RMS: The average energy in a time domain signal. In the example to the right the RMS value is about 0.9 g. The exact formula is Sqrt(Sum((xi)2) for all measurement values xi

Crest: The ratio of the peak value divided by the RMS value:

Crest = Peak value/RMS value

In the example to the right the Crest value is about 16.8. It has no unit

The Crest value is a good indication of the ‘Peakiness’ in a signal. Good gears have a Crest value of 3-8, bad gears have a Crest value from 10 to 30.

Tickeval: The Tickeval value indicates the maximum difference of short-time spectra taken over the revolution from the average short-time spectrum for the revolution. Good gears have values of 6, bad gears have values above 12.



Peak

RMS

9.11.2009 14

Separation of Gear Errors

The acoustical signal holds the components of both gears.

Knowing the transmission ratio, the periodicity of each gear can be found. Gear mesh components only depend on the pairing of the gears.

Eccentricities and surface errors can be separated because they have a cycle that corresponds to the originating gear. The following errors can contributed individually:

� Eccentricities, � Deviation from circular shape� Tooth spacing� Surface waves (Ghost Orders)� Nicks

Z1

16

Z2

20

Z 1

1 6

Z 2

2 0

The gear mesh componentdepends on the pairing

Eccentricities and surfaceerrors can be contributedindividually.

16

20

16

20

9.11.2009 15

Fourier transform: Order spectrum

Time Domain Versus Order Domain I

5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 Ord

60

70

80

90

100

dBV

Oran.SK1

5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 Ord

60

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100

dBV

Oran.SK1

400 800 1200160020002400280032003600m Rev

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V

Oran.SK1

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2.0

V

Oran.SK1

Sinesmooth gear contact

Order at number of teeht: 5Base order H1

400 800 1200160020002400280032003600m Rev

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V

Oran.SK1

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1.0

2.0

V

Oran.SK1

5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 Ord

60

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100

dBV

Oran.SK1

5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 Ord

60

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100

dBV

Oran.SK1

Triangharsher gear mesh

Harmonics at odd multiplesof nr of teeth (5)H1, H3, H5, ..

400 800 1200160020002400280032003600m Rev

-2.0

-1.0

0.0

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V

Oran.SK1

400 800 1200160020002400280032003600m Rev

-2.0

-1.0

0.0

1.0

2.0

V

Oran.SK1

5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 Ord

60

70

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100

dBV

Oran.SK1

5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 Ord

60

70

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100

dBV

Oran.SK1

Sawtoothharsh gear mesh

Strong harmonics of number ofteeth (5)H1, H2, H3, ..

Gear with 5 teeth, 4 revolutions

9.11.2009 16

Fouriertransformation: Ordnungsspektrum

Time Domain Versus Order Domain II, Modulations

400 800 1200160020002400280032003600m Rev

-2.0

-1.0

0.0

1.0

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V

Oran.SK1

400 800 1200160020002400280032003600m Rev

-2.0

-1.0

0.0

1.0

2.0

V

Oran.SK1

5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 Ord

60

70

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100

dBV

Oran.SK1

5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 Ord

60

70

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100

dBV

Oran.SK1

Sine with modulating sineSmooth gear mesh witheccentricity

Order at nr of teeth H1 with side bands +/- 1 order

5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 Ord

60

70

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100

dBV

Oran.SK1

5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 Ord

60

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100

dBV

Oran.SK1

400 800 1200160020002400280032003600m Rev

-2.0

-1.0

0.0

1.0

2.0

V

Oran.SK1

400 800 1200160020002400280032003600m Rev

-2.0

-1.0

0.0

1.0

2.0

V

Oran.SK1

Triang with modulating sineharsher gear mesh witheccentricity

Harmonics H1, .. withside bands +/- 1 order

400 800 1200160020002400280032003600m Rev

-2.0

-1.0

0.0

1.0

2.0

V

Oran.SK1

400 800 1200160020002400280032003600m Rev

-2.0

-1.0

0.0

1.0

2.0

V

Oran.SK1

5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 Ord

60

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dBV

Oran.SK1

5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 Ord

60

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dBV

Oran.SK1

Triang with modulating triangharsher gear mesh withseveral eccentricities

Harmonics H1, .. withside bands +/- n.Order

Gear with 5 teeth, 4 revolutions

9.11.2009 17

50 60 70 80 90 100 110 120 130 Ord

40

50

60

70

80

dBV

Mix

Antrieb

Revolution synchronous averaging gives periodic (cyclic) signals. This corresponds to the cyclic nature of the gear sets.

These signals can be transformed into the spectral domain without any time domain leakage windows.

This allows for high spectral resolution. Eccentricities can be easily distinguished from the gear mesh orders. The noise components can be attributed to their origins.

Blue: Conventional order spectrum with Kaiser Bessel Window

Green: Revolution synchronous order spectrum without window function

Synchronous Averaging III

GM 2 *GM

Ecc.. GhostOrders

9.11.2009 18

Order spectra of a lay shaft transmission

8.0 16.0 24.0 32.0 40.0 48.0 56.0 64.0 72.0 Ord

70

80

90

100

110

dBg

AW

SK1-lim

70

80

90

100

110

dBg

VGW

SK2-lim

70

80

90

100

110

dBg

HW

SK3-lim

70

80

90

100

110

dBg

Mix

Mix-lim

8.0 16.0 24.0 32.0 40.0 48.0 56.0 64.0 72.0 Ord

70

80

90

100

110

dBg

AW

SK1-lim

70

80

90

100

110

dBg

VGW

SK2-lim

70

80

90

100

110

dBg

HW

SK3-lim

70

80

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100

110

dBg

Mix

Mix-lim

Input

VGW

HW

Mix

Input H1 Input H2

VZ1 H1 VZ1 H2VZ5 H1 VZ5 H2

5. Gg H1 5. Gg H2OW 5. Gg

-10 dB-12 dB

Limits:red

O-Spectra:black

Input: 26 ZVZ1: 35 ZVZ 4: 43 Z5. Gear 27 Zi = 1.1764

9.11.2009 19

Evaluation of Order Spectra

10 20 30 40 50 60 70 80 90 Ord

45

60

75

90

105

dBgVGW

VGW-lim

The order spectra of the synchronous channels and of the mix channel are compared with alimit curve. Every order of the limit curvehas an underlying error code. This error codeis generated from transmission ratios in a semiautomatic fashion. If the limit curveis exceeded, the error code gives rise to anerror message in plain text.

The limit curves consist of portions, whichare generated by a learning process and ofportions which are set to fixed values.

The learn rnode is used for those spectralportions, where there are results from driving experiments available yet. Generally thisholds true for tooth spacing problems,ghost orders and bearing noise (in themix channel).Fixed limits are adopted from driving experiments,usually for the gear mesh and for the side bands.

9.11.2009 20

Measurement Report

A protocol is generated for every unit. It holds information about unit type,serial number, time of measurementand defect report.

There are three kinds of report:

Short:: serial numbers only for goodunits, defect report for failing units.Normal: Report line for every unitLong: All measurement values in tabular form.

Around 300 measurement resultsare stored in a protocol database forstatistical evaluation. 5000 units useabout 20 Mbyte of disk space.

The test stand control system can request several protocol variantsfor own recording purposes.

9.11.2009 21

10 20 30 40 50 60 70 80 90 Ord

20

40

60

80

100

dBg

MaxBnd

MinBnd

StdDev

AW-avg

SK1-lim

10 20 30 40 50 60 70 80 90 Ord

20

40

60

80

100

dBg

MaxBnd

MinBnd

StdDev

AW-avg

SK1-lim

Spectral Limits

Limit curve from Average + Offset + n times standard deviation. Overridden by minimum and maximum polygons and by the fixed hats.

Hats for gear mesh orders and their side bands

9.11.2009 22

Learning

For all measurements, the following statisticalproperties are computed:

Average (AV) undStandard deviation (STD)

From these numbers, a limit L is generatedaccording to

L = AV + Offset + n* STD.

The offset and the multiplier of the standard deviation is selectable. For spectral measures,an offset of 5 dB and a std-factor of 3 is normally used. Maximum and minimum values set upper and lower bounds for the limit L.

A new learn consist of a base learn (usually 5 units), where all units are accepted that are below maximum polygons and below hats.

The base learn is followed by an additional learning (usually 100 units). Here every unit is evaluated against the already established limitcurves. Only error free units will be added to the learning sample.

Another available choice consists of a indefinite learn process with a selectable time constant.

During the whole learning process, the fixed limits apply. This assures, that all known data (like limits from car experiments) will be used as a guidance during the process.

What is learned Learning methods

9.11.2009 23

Cabin noise components

Noise sources

There are many different transfer paths for the sound and the vibration from the gearset to the drivers ear.

Each path has its own frequency dependent transfer function

Noise from the motor, wind and tires may mask certain frequency bands from the gears.

These effects induce the speed, torque and vehicle dependent noise perception of the gear sets.

Transfer paths

9.11.2009 24

Averaging over microphone postions

M2M1 M3 M4 AccelSpeed

OrderResamp

FFT

+

Average

Spectro-gramm

Order-tracks

To compensate for the cabin resonance's, four microphones are positioned within the cabin:Front left, middle and right position, one in the rear. The energy of the microphone signals is averaged in the spectral order domain.

One sensor is mounted on the transmission to allow for the simultaneous analysis of the gearbox vibration data.

9.11.2009 25

Order spectrograms

Order spectrograms are recorded for the gearbox vibration signal and for the cabin sound field.

From these order tracks for arbitrary orders and order spectra for arbitrary speeds can be generated:

1) Ordnungs-Spektrogramm 4. Gang Zug

Order track for the 65. order

2) Order spectrum at 2241 RPM

9.11.2009 26

Vibration and Cabin Noise, Spectral Cuts

Spectral Cut Cabin Noise: 12 db higher than background at 2640 RPM/110 Km/h

12 dB

Spectral Cut Vibration: 50th order of 100 dBg at 2700 RPM

9.11.2009 27

Vibration and Cabin Noise, Order Cuts

9.11.2009 28

Order Tracking

The critical noise sources in a car are usually the gear mesh orders and their sidebands.

These noise sources are highly speed dependent. Detailed speed dependent evaluation uses the track of mesh orders and sidebands over speed.

The gear mesh H1 base order and its harmonics are tracked over speed and compared with speed dependet limit curves.

The track form depends on torque, drive/coast and on the resonances within the gearbox and the test stand.

Within speed bands, average and maximum amplitudes can be evaluated and compared to limits. The single values are ideal for statistical analysis over time. Speed band

Tracked Value Curve 1 Curve 2 H1 Max Bd1 79.1 dB 75.5 dBH1 Aver Bd1 76.2 dB 71.9 dB

9.11.2009 29

Shown are measurements with the GSW shift roboter, which measures forces and displacement directly at the transmission shift mechanism.

Shifting effort is shown versus displacement

Positive forces: Shift into a gear

Negative forces: Shifting out of gear

A: Synchronisation work when shifting into a gear. Good repeatability

B: Shifting through after synchronisation. Varying force.

C: Shifting out. Small forces for good transmissions

D: Synchron ring missing

Shift force evaluation

AB

C

AB

C

AB

C

A B

C

A B

C

A B

C

D

D

9.11.2009 30

Evaluation of shifting effort versus lever displacement.

The synchronization is evaluated via the work that is needed (F*s). Therefore, the area of the curve above a window A is computed (work = force * displacement) . D: a transmission without a synchron ring.

The maximum force during shifting into a gear are limited with the polygon B

The maximum forces when shifting out are limited with a polygon C.

End position: a settable end position must be reached when shifting is finished.

Evaluation of Shifting Effort

AB

C

D

Schaltkraft über Weg für 150 Seriengetriebe. Bewertungsfenster erkennen fehlende Synchronringe und Schwergängigkeiten.

9.11.2009 31

Management of Multiple Test Benches

Server

Parameter Setting and Statistical Evaluation

Test Benches

Intranet

DataParameter

PC withInternet Explorer

Central archive of test results Parameter setting and statistical evaluation from every PC with intranet access.

9.11.2009 32

RotasAnalyzerRotas

Analyzer

MeasurementDatabase

MeasurementDatabase

Measurement Archives

Measurement Archives

RotasPresentation

RotasPresentation

Intranet StatisticsIntranet Statistics

Rotas Data Flow

Server or Test Stand

Test Stand

Work Group PC

Work Group PC has presentation software installedCan use Intranet statistcis via Internet Explorer

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ROTASAnalyzer

Measurement System Server

Measurement Database

SQL Server 2000

Measurement Database

SQL Server 2000

Arc

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\outbox: \inbox:

Collector Service

Parameter Database

Parameter Database

Local Copy

Measurement Transfer over Network

9.11.2009 34

Order Spectra

Spectra are stored for the individual rotors in the transmission

An additonial Mix spectrum represents the order amplitudes of all parts combined

The spectra are either peak hold amplitudes or averaged amplitudes over a ramp

Limits can be self learned or manually set. The amplitude of gear mesh orders can be set individually by a database

9.11.2009 35

Order spectra of production units can be displayed in Campbell or in 3-D graphs. Cuts in the order or in the unit direction show order amplitude versus units or the spectrum of one unit. The pictures show the order spectra of 300 production units. A ghost order of 118 is present in the first 40 units tested.

Spectral Statistics

9.11.2009 36

Order Tracks

During the ramps, spectral components are evaluated over the speed.

Usually, the main gear mesh orders and their harmonics are tracked.

In addition, energy in order bands may be tracked as well.

Track limits (shown in red) can be self learned or set manually.

9.11.2009 37

Complete Data Report of a single Unit

Macro controlled display of archived data.

The database is used for searching of serial numbers, test results etc.

Then the presentation software displays a full measurement report

Sensor Group 1

9.11.2009 38

Intranet Statistics

The information of the SQL measurement database can be retrieved via the intranet.

The production results and the measurements can be seen online.

An arbitrary time interval can be selected for the analysis.

9.11.2009 39

Statistical Evaulation for Types and Benches

Test results The evaluation can be done over gearbox types or over test benches.

Any time interval can be specified.

9.11.2009 40

Measurement Statistics and Bench Comparison

Over 300 individual measurement results can be evaluated.

The comparison of test benches makes it easy to administer large production facilities.

9.11.2009 41

Reject Analysis, Top n and Type Specific

The results are shown both in tabular and in graphical form

9.11.2009 1 Transmissions, Gearboxes and Axles RotasPro Noise Analysis.

Documents

Transcript of 9.11.2009 1 Transmissions, Gearboxes and Axles RotasPro Noise Analysis.