Tritech International Vehicle Sonar Developments Mike Broadbent Business Development Manager Oceanology 2012 - UUVS
Overview About Tritech Mechanical Scanning Sonar - Improving the performance High Speed Imaging Multibeam the new generation of sonar AUV Operations what are the options?
About Tritech Our UK Locations: Head Office. Aberdeen Scotland. Our Global Distributor Network: Design & Production. Ulverston England. Our Industry Sectors: ENERGY Oil & Gas Renewable Hydro-Electric DEFENCE Military & MCM Law Enforcement Search & Rescue ENGINEERING Construction Civil Engineering Nuclear SURVEY Oceanographic Hydrographic Archaeology
The UUV product groups Seeing the way ahead: Mechanical Scanning Sonar Multibeam Imaging Sonar Cameras & Lighting Knowing the Vehicle Position: Precision Echo Sounders Bathymetric Systems igc & ifg USBL Tracking System Scanning the Seabed: Multibeam Imaging Sonar ROV Side Scan Sub Bottom Profiler Profiling Sonar 3D Imaging Sonar
Mechanical Scanning Sonar Improving the Performance
From Super Size to Super SeaKing DST The evolution of the UUV Scanning Sonar The Technological Steps: Digital electronics Composite Transducers CHIRP DST
Introduction of Composite Technology The Broadband Transducer Composite Transducer technology takes standard PZT material, slices and dices it into individual pillars, and encapsulates the pillars into a polymer matrix. The benefits: Broadband frequency response Better impedance matching to water Improved sensitivity in the thickness mode Greater range capability Acoustic shading can be designed into the transducer element for improved sidelobe suppression Monolithic Composite
Improved Sidelobe Suppression The Limitations of Monolithic To understand the benefits of sidelobe suppression, we need to analyze the limitations when using conventional Monolithic Transducers. Sidelobes can produce unwanted signals from acoustic reflections out of the main beam of the transducer. The sonar can t determine if the acoustic reflection is in the main beam or sidelobe. The Monolithic Beam Plot Response: Main Beam - wanted Side lobes - unwanted The sonar plotter will plot the unwanted signal at the bearing of the main beam. Monolithic Transducer Element
Improved Sidelobe Suppression The Benefits of Composite With appropriate shading designed into the composite transducer element:- The Composite Beam Plot Response: Main Beam - wanted The sidelobes are reduced to near zero. Side lobes - supressed Unwanted signals from reflections out of the main beam are minimised. The sonar plotter will plot a more realistic and less blurred image of the underwater scene. Composite Transducer Element
Introduction of DST CHIRP Technology CHIRP is an acronym for Compressed High Intensity Radar Pulse The frequency within the burst is swept over a broad range throughout the duration of transmit pulse. This creates a 'signature' acoustic pulse; the sonar knows what was transmitted and when. Using 'pattern-matching' techniques, it can now look for its own unique signature being echoed back from targets. Monotonic: CHIRP: The Benefits: Improved Signal to Noise Greater range capability Improved range resolution
Improved Range Resolution Limitations of the Monotonic techniques To understand the benefits of CHIRP, we need to analyze the limitations when using conventional single frequency (monotonic) techniques The ability of the acoustic system to resolve targets is determined by the pulse length. To get enough acoustic energy into the water for good target identification the transmit pulse length has to be relatively long. Range resolution = (pulse length x velocity of sound) / 2 A 50usec Pulse = 37.5mm Resolution (assuming 1500m/sec vos)
Improved Range Resolution The Benefits of CHIRP With CHIRP DST techniques we can:- Transmit longer pulses for good target identification and long range performance. Achieve improved range resolution due to matched filter receiver. Range resolution = Velocity of sound/(bandwidth*2) A 50usec Pulse = 7.5mm Resolution (assuming bandwidth of 100kHz) A theoretical improvement by a factor of 5!
CHIRP DST The Results To demonstrate the benefits of CHIRP, an experiment was conducted using a sample of chain in a test tank. Monotonic Sonar blurred image CHIRP Sonar chain links clearly visible
Tritech Mechanical Scanning DST Sonars today Ultra Compact Sonar Advanced Broadband Sonar Dual Frequency Sonar
Ultra Compact Sonar Micron DST 78.5mm Ultra small size bringing sonar capability to the smallest of underwater vehicles 75m (246ft) Operating Range 700kHz CHIRP Operating Frequency Hard boot protection for transducer Depth rated to 750m (2,460ft) 3000m (9842ft) option 35 Vertical 3 Horizontal 700kHz CHIRP
Advanced Broadband Sonar Super SeaPrince DST 146mm Broadband capability for improved range, resolution and flexibility 100m (328ft) Operating Range 675kHz CHIRP Operating Frequency Broadband capability (500kHz 900kHz) Hard boot protection for transducer Depth rated to 4000m (13,123ft) 38 Vertical 2.3 Horizontal 675Khz CHIRP
Dual Frequency Sonar Super SeaKing DST 225mm Dual mode capability providing Low frequency for long range sonar visibility, and High frequency for medium range high resolution images Advanced Dual Transducer Low Frequency Mode: 325kHz CHIRP Operating Frequency 300m (984ft) Operating Range High Frequency Mode: 675kHz CHIRP Operating Frequency 100m (328ft) Operating Range Depth Rated to 4000m (13,123ft) 6800m (22,309ft) option
Dual Frequency Sonar Super SeaKing DST Long Range (325kHz Transducer) 325kHz Short Range (675kHz Transducer) 675kHz 20 Vertical Beam 3 Horizontal Beam 300m 100m 40 Vertical Beam 1.8 Horizontal Beam Dual transducers result in a beamwidth which is optimised for application.
The Surface Control & Display Software SeaNet Pro V2 Interface to all existing and new Tritech subsea sensors (including multibeam) Display a multitude of Tritech sensors and third party data at any one time Customise window layout to user preference Wizard driven Geo-referenced Sonar data Output functions Remote networkability Auto Dynamic Range
High Speed Imaging Multibeam the new generation of sonar
Multibeam Imaging Sonar Gemini 720i Multibeam set new standards for underwater vehicle sonars. It offers a real-time high frequency imaging solution which is suitable for the very small ROVs and AUVs. The Benefits: Real-time imaging provides easy interpretation and rapid visualisation. Advanced composite transducers and time-delay beamforming provide sharp high resolution imagery across the full field of view. Wide bandwidth provides range resolution of 8mm. 256 dynamically focused beams provide high resolution near field imagery to 0.2m Mech Scan Sonar single Beam Multibeam Sonar 256 Beams
Multibeam Imaging Sonar Gemini 720i Curved transmitter array provides even power distribution across the full field of view. Transducers angled 10 down provide optimum seafloor coverage and range performance. Transducer spec: 720kHz operating frequency 120 horizontal field of view. 20 vertical beam (tilted down by 10 ) 256 beams 1 Acoustic Angular Resolution 0.5 effective angular resolution
Multibeam Imaging Sonar Gemini 720i Integrated Sound Velocity Sensor provides constant updates of VOS ensuring accurate target imaging. Fast Ethernet (10/100baseT) comms and VDSL for twisted pair cables to 1000m. Solid state therefore inherently more reliable. The Disadvantages of Mutibeam: Several units required to cover 360 field of view. Higher cost than Mech Scanning Sonar.
Multibeam Imaging Sonar Gemini 720i in operation Medium Range Obstacle Avoidance Short Range Inspection Mattress Inspection Courtesy Acergy
AUV Operations What are the options?
Mech Scanning Sonar in AUV Applications Some of the Options Ultra Compact Sonar: Advanced Broadband Sonar: Dual Frequency Sonar:
Mech Scanning Sonar in AUV Applications Some of the Options Add Sidescan capability: Tritech Single Frequency options: 325kHz - 1 BW, 180m acoustic slant range. 675kHz - 0.5 BW, 120m acoustic slant range. CHIRP technology. Low power requirement. Very cost effective. Other Manufacturers Options: Dual Frequency. Synthetic Aperture SS options
Mech Scanning Sonar in AUV Applications The Software Interface
Mech Scanning Sonar in AUV Applications The Software Interface
Mech Scanning Sonar in AUV Applications SeaNet Post Mission Analysis
Multibeam Sonar in AUV Applications Some of the Options Gemini 720i Sonar: Custom Gemini 720i Sonar: DLL DLL SDK DLL to support high level computer programming.
Multibeam Sonar in AUV Applications The Gemini SDK A DLL acts as the interface between the Sonar Head and the Seanet and Gemini software packages. The SDK provides the software engineer with the tools to implement this interface into other software packages such as an AUV control program. DLL available for Win32 and Linux. Etc. etc..
Multibeam Sonar in AUV Applications The Gemini SDK The data returned by the Gemini sonar covers a field of view of 120 degrees. Each line of data returned consists of 256 values representing the image from -60 to +60 degrees at a particular range. The range resolution is 8mm.
Multibeam Sonar in AUV Applications Gemini EVO Post Mission Analysis
Gemini 720i Sonar in an AUV Application CAUV Cambridge Autonomous Underwater Vehicle Photos Courtesy of Simon Rogerson SCUBA magazine CAUV is a student developed autonomous submarine. The CAUV team are developing small AUVs for use under the Arctic ice sheets. Barracuda is one of their AUV platforms. Barracuda Image Courtesy of James Rickenbach CAUV
The UUV product groups