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IXSEA presentation of 10 november 2011 Flat bandwith low frequency tranducers and processing for Hydrographic and Seismic applications

IXSEA presentation of 10 november 2011 Flat bandwith low frequency tranducers and processing for Hydrographic and Seismic applications

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  • 1. Low Frequency Sound Technologies HSB Workshop, Rotterdam, 10/11/2011, Frederic Mosca, PhD
  • 2. Contents
    • Ixsea Overview
    • High Resolution Seismic Reflection Theory
    • Low Frequency Sound Technology
    • ECHOES Results
  • 3. IXSEA Overview
    • 220 Employees
    • TurnOver 2010 : 41M€
    SYSTEMS SOLUTIONS PRODUCTS TECHNOLOGIES
  • 4. IXSEA Products and Technologies
    • Inertial Product Division: Gyrocompas and Navigation Sensors
    • (120 people in Marly)
    • Acoustic Product Division: Acoustic Positionning and Mooring
    • (50 people in Brest)
    • Sonar System Division: Acoustic Imaging (30 people in La Ciotat)
  • 5. Acoustic Research & Technology
    • 15 people in La Ciotat
      • Synthetic Aperture Sonar
      • Multi Beam Echo Sounder (fishing trancking, phase detection, bottom classification)
      • Low Frequency Sound Technology
      • Fiber Optic Hydrophone
      • Acoustic Barrier (active and passive)
      • Non Linear Acoustic (parametric and harmonic)
  • 6. Low Frequency Sound Technology Low Frequency 0.1 kHz 1 kHz 10 kHz 100 kHz 1000 kHz 1000 km 100 km 10 km 1 km 0.1 km Seismic Subbottom Profilers Passive Military Sonars Active Military Sonars Transmission and Positionning Imaging Sonar (SSS, SAS) MultiBeam Echo Sounder Fishery Echo Sounders and Sonars Acoustic Camera
  • 7. High Resolution Seismic Reflection
    • Or Subbottom Profiling, or Sediment Profiling
    • 20’s: Seismic Reflection
      • Large geophysical structure
      • Penetration : > 1 km
      • Resolution : ~10 m
    • 70’s: High Resolution Seismic Reflection
      • Fine sedimentary composition
      • Penetration: ~100m
      • Resolution: <1m
    • Oil Exploration
    • Geophysic Investigations
    • Mineral Explorations
    • Seafloor Process Investigations
    • Underwater Engineering
    • Hydrography
    • Quaternary Mapping
    • Habitat Studies
    • Archeology
  • 8. High Resolution Seismic Reflection: Principle Platform Trajectory Water Column Signal enveloppe Seismic profile Ref. X.Lurton, An introduction to Underwater Acoustics
  • 9. High Resolution Seismic Reflection: Theory
    • Reflection of sound at a boundary between 2 different media
    • Different media in acoustic:
    • Plane wave reflection coefficient:
    At each interface an echo is generated Medium 1 Medium 2 p i p t p r
  • 10. High Resolution Seismic Reflection: Theory
    • Scattering by Surface Roughness
    • True plane wave reflection coefficient:
    • With R, the Rayleigh parameter:
    Medium 1 Medium 2 p i p t p r h θ
  • 11. High Resolution Seismic Reflection: key parameters
    • Detection of the reflected waves at the receiver depends on:
      • Source amplitude
      • Energy loss processes : spherical spreading and absorption
      • Reflection coefficient amplitude
      • Receivers geometry and sensitivity
      • Ambient noise level at the detector
  • 12. High Resolution Seismic Reflection: key parameters
    • Detection of the reflected waves at the receiver depends on:
      • Source amplitude
      • Energy loss processes : spherical spreading and absorption
      • Reflection coefficient amplitude
      • Receivers geometry and sensitivity
      • Ambient noise level at the detector
    Work near the bottom Solid state source
  • 13. High Resolution Seismic Reflection: key parameters
    • Detection of the reflected waves at the receiver depends on:
      • Source amplitude
      • Energy loss processes : spherical spreading and absorption
      • Reflection coefficient amplitude
      • Receivers geometry and sensitivity
      • Ambient noise level at the detector
    Working at low frequency
  • 14. High Resolution Seismic Reflection: key parameters
    • Detection of the reflected waves at the receiver depends on:
      • Source amplitude
      • Energy loss processes : spherical spreading and absorption
      • Reflection coefficient amplitude
      • Receivers geometry and sensitivity
      • Ambient noise level at the detector
    • Receiving antenna position
    • Platform self-noise reduction
    • Tow-fish or UUV
    • Baffling
    • Antenna length
    • Bottom slope
  • 15. High Resolution Seismic Reflection: Linear System Theory
    • From a Linear System Theory point of view:
    Source Function Medium Function Sediment column Dirac comb
  • 16. High Resolution Seismic Reflection: Source spectrum effect
    • Dirac comb convolution
    Sediment column Absorption Ideally flat BW source F t Sediment column Absorption Real source F t
  • 17. High Resolution Seismic Reflection: Image quality
    • Resolution:
    • Contrast:
    SL Source Level Spectrum F SL max SL max -3dB B A 0 A 0 /2 A t T A s
  • 18. High Resolution Seismic Reflection: Intrinsic tradeoff
    • Good penetration = Low Frequency
    • Good image quality = Large Source Bandwidth
    • Bandwidth proportionnal to frequency (quality factor, Q)
    • So Good image quality = High Frequency
  • 19. High Resolution Seismic Reflection: Sound technologies
    • Accelerating Water Mass
      • Boomers
      • Air guns
      • Sleeve guns
    • Implosive Source
      • Vaporchoc
      • Flexichoc
      • Water guns
    • Explosive Source
      • Dynamite, gas exploders, blasting gaps
      • Sparkers
    • Controlled waveform
      • Piezoelectric transducers
      • Magnetostrictive transducers
    Ref. Woods Hole University website Air Gun Principle Ref. Woods Hole University website
  • 20. High Resolution Seismic Reflection: Sound technologies Impulsive source Resonant source Poor Performance… … but strong potential Ref. Verbeek et al. (1995) ; Moscher et al. (1999) Boomer Airgun Sparker Piezoelectric Energy output High (230dB) High (235dB) Medium (225dB) Low (215dB) Typical BW 0.5-5kHz 20-300Hz 0.5-5kHz Q = 10% Arbitrary WF No No No Yes Directivity Yes No No Yes Repeatability High Poor Poor High Deep-tow Capability No No <1000m Full depth Other Bubble pulse Bubble pulse
  • 21. High Resolution Seismic Reflection: Chirp technology
    • From Radar technology. Schock et al., 1989
    • Linear frequency modulated pulse:
      • B = bandwidth
      • T = pulse duration
      • f 0 = central frequency
    • Auto-correlation property
    c/2B B.T
  • 22. High Resolution Seismic Reflection: Chirp technology Sediment column Absorption Pulse source F t Sediment column Absorption Chirp source F Better penetration
  • 23. High Resolution Seismic Reflection: Chirp technology
    • Process Gain: PG = 10log(BT) ~ 20dB
      • For instance B = 2kHz and T = 50ms
    How increasing Q ? Boomer Airgun Sparker Piezoelectric Energy output High (230dB) High (235dB) Medium (225dB) High (235dB) After pulse compression Typical BW 0.5-5kHz 20-300Hz 0.5-5kHz Q = 10% Arbitrary WF No No No Yes Directivity Yes No No Yes Repeatability High Poor Poor High Deep-tow Capability No No <1000m Full depth Other Bubble pulse Bubble pulse
  • 24. Low Frequency Sound Technology: Coupled resonator
  • 25. Low Frequency Sound Technology: Design Process
    • Analytical Model
    • Equivalent Circuit Model
    • Finite Element Modeling
    • Prototyping
    • Test in Tank or Lake
    • Design evaluation
  • 26. Low Frequency Sound Technology: Flapping Tonpilz
    • Piezoelectric Stack
      • Dilatation / Compression resonator
      • Motor
      • Pre-stress
    • Tail Mass
      • Unidirectionnal transmission
    • Head Mass
      • Acoustic Impedance Matching
      • Flapping Disc Resonator
    Q = 100% High SL Depth limited
  • 27. Low Frequency Sound Technology: Janus-Helmholtz
    • Janus
      • Symetric transducer
      • Nodal plane
    • Fluid cavity
      • Helmholtz resonator
    Q = 100% Full Depth Medium SL
  • 28. Low Frequency Sound Technology: Bandwidth Flatness
    • Bandwidth Flatness Matters:
  • 29. Low Frequency Sound Technology: Transmission Chain Power Amplifier Transducer Waveform Generator Power Supply Impedance Matching 10dB
  • 30. Low Frequency Sound Technology: Transmission Chain Power Amplifier Transducer Waveform Generator Power Supply Impedance Matching 3dB Compensation Stage
  • 31. High Resolution Seismic Reflection: Sound technologies Boomer Airgun Sparker Flapping Tonpilz Janus-Helmholtz Energy output High (230dB) High (235dB) Medium (225dB) High (235dB) After pulse compression Medium (225dB) After pulse compression Typical BW 0.5-5kHz 20-300Hz 0.5-5kHz Q = 100% Q = 100% Arbitrary WF No No No Yes Yes Directivity Yes No No Yes No Repeatability High Poor Poor High High Deep-tow Capability No No <1000m No Full Depth Other Bubble pulse Bubble pulse Bad Weather Operability
  • 32. High Resolution Seismic Reflection: ECHOES Family 600Hz 1500 Hz 3500 Hz 5000 Hz 10000 Hz
  • 33. ECHOES 1500 : Description
      • BW = 650Hz – 2500Hz
      • Source Level : 200dB (ref.1µPa@1m) (@2kW)
      • Equivalent Source Level : 225dB (ref.1µPa@1m)
      • Typical Resolution : 40cm
      • Typical Penetration : 250m
      • Full Depth Capability
      • Bad Weather Operability
      • Application
        • HR Seismic (Boomer/Sparker Range)
        • Acoustic Tomography
        • Long Range Communication
      • References:
        • IFREMER
        • Universities (Tokyo, Alger)
        • DORD, TUS, Svarog, De Beers
    GAPS Beacon GPS Underwater Housing (power supply, synchro, com’ ) Phins 6000 Echoes 1500 6000m
  • 34. ECHOES 1500 : Results 55ms 145ms 400m 40cm resolution
  • 35. ECHOES 3500 : Description
      • BW = 1800Hz – 5200Hz
      • Source Level : 210dB (ref.1µPa@1m) (@3kW)
      • Equivalent Source Level : 235dB (ref.1µPa@1m)
      • Typical Resolution : 20cm
      • Typical Penetration : 100m
      • Hull-mounted
      • 6000m Water Column Capability
      • Application
        • HR Seismic
        • Hydrographic / Oceanographic Vessel
      • References:
        • IFREMER (3 vessels)
        • Hydrographic Institute (France, Portugal)
        • Yuzmorgheo, P.R. China
  • 36. ECHOES 3500: Results 605ms 870ms 150m penetration
  • 37. ECHOES 5000: Description
      • BW = 2000Hz – 8000Hz
      • Source Level : 190dB (ref.1µPa@1m) (@1kW)
      • Equivalent Source Level : 215dB (ref.1µPa@1m)
      • Typical Resolution : 12cm
      • Typical Penetration : 50m
      • Tow fish, Pole-mounted, AUV
      • Full-depth Capability
      • Application
        • HR Seismic
        • UUV payload
        • Coastal and Lake survey
      • References:
        • IFREMER (AUV ASTERIX, ROV VICTOR 6000)
        • MARUM
        • La Rochelle University
  • 38. ECHOES 10000: Description
      • BW = 5000Hz – 15000Hz
      • Source Level : 210dB (ref.1µPa@1m) (@2kW)
      • Equivalent Source Level : 230dB (ref.1µPa@1m)
      • Typical Resolution : 7cm
      • Typical Penetration : 10m - 20m
      • Hull-mounted, Pole-mounted
      • Application
        • HR Seismic (Parametric SBP range)
        • Mine detection
        • Archeology
      • References:
        • IXSURVEY
  • 39. ECHOES 10000: Results 0ms 25ms 4m
  • 40. ECHOES 10000 vs ECHOES 5000 10kHZ 5kHZ
  • 41. Conclusion and further research
    • SBP = tradeoff between resolution and penetration
    • Chirp Technology
    • Bandwidth Matters! (Large and Flat)
    • Technologies:
      • Flapping Tonpilz
      • Janus-Helmholtz
      • Compensation stage
    • Other research
      • Janus-Hammer Bell for Very Long Range Acoustic Communication
      • High Signal-to-Noise Ratio Fiber Optic Hydrophone
      • Mills Cross Parametric Communication
    100bits/s @ 1000km DSS0 – 10dB
  • 42. Thank you! Questions ?