Multibeam data quality assurance at Genavir. Karine Abel Michaux

Transcription

1 Multibeam data quality assurance at Genavir Hervé Bisquay Karine Abel Michaux Pascal Viollette

2 GENAVIR Genavir is the operator of the civilian french oceanographic fleets : 10 vessels / 5 deep water vehicles / seismic equipment Status Group of Economic Interest Employes Missions 320, including : - crewmen (200) - technical staff (70) - vessels and underwater vehicles operations - vessels and equipment maintenance - data acquisition and data quality assurance - navigation and QC software development

3 Kongsberg Swath sonars operated by Genavir Vessels vessels sonars Frequency (khz) Marion Dufresne (120 m) L Atalante (80 m) Thalassa (75 m) L Europe (30 m) EM EM EM EM EM EM /300/400 ME70 90 ME70 90 EM /300/400 Thalia (25 m) EM2040D 200/300/400 Haliotis (9 m) Geoswath 250 Alis (30 m) EM Underwater vehicles AsterX (AUV 3000 m) EM /300/400 IdefX (AUV 3000 m) EM /300/400 Ariane (HROV ) EM /300/400

4 The largest vessel Marion Dufresne 120 m EM122 / SBP120 / EM710 The smallest Haliotis 9 m Geoswath 250 khz

5 MB data acquisition on board french vessels The actors Who is responsible for what? Scientific staff (Ifremer, university or other institute) The customer : - survey operations management - data post processing Electronic Technical Officers (Genavir - crew members) Responsible for the electronic equipment - maintenance Multibeam operators (Genavir) MB real time operations Post processing operators (Genavir) Data post processing (on-demand)

6 Data flow Onboard ashore Portable hard disks (hand carried) ftp transfer Multibeam data acquisition : - EM data : SIS (.all,.wcd,.kmall) ARTECH Genavir Technical intermediate data base (one year of data) SISMER French national marine scientific data base Genavir QC

7 Genavir quality plan A quality plan for each equipment type describes : - the nature and the level of the data that has to be supplied by Genavir - the quality assurance procedures Navigation data : L, G, Z (vessels and underwater systems) Genavir has to provide «level 2» data. Level 2 : data corrected and validated Other data (including multibeam : - Bathymetry - Seabed image - Watercolumn ) Genavir has to provide «level 1» data. Level 1 : technical validation (correction of instrumentation errors )

8 Genavir Documentation DINES documents (for each equipment) Acquisition Guidelines (for each vessel) Data archiving guidelines (for each vessel) Genavir cook books (for each equipment) - description of the equipment - Performances (accuracy, resolution, max range ) - Operating recommandations (survey lines, parameters settings ) - Equipement parameters settings - Quality control - Data logging guidance - Genavir operating and maintenance manuals Scientific staff Electronic officers and multibeam operators

9 Performances control and monitoring Transducer tests Electrical measurements Every year Acoustic performances - Self noise level measurements - Swath width control Every year Patch tests and control on test areas -roll/pitch/heading calibration - bathy/imagery accuracy testing - Positioning accuracy testing -After each critical change : - HW or SW upgrade - transducer or motion sensor displacement (every year for coastal vessels)

10 Transducers control Measurement of the electrical impedance Method 1 : with an external tool (Impedance analyser -> Hioki) Example : L Atalante EM122 Tx 48 modules 1 module = 18 channels

11 Transducers control Measurement of the electrical impedance Method 2 : Kongsberg (telnet bist tool) Example : L Atalante EM122 Tx 48 modules 1 module = 18 channels Total = 864 channels Z@12 khz

12 Self Noise level measurement The aim -> to check the acoustic performances of the equipment / vessel Kongsberg Bist : Measurement of the noise on the Receive transducers Example : L Atalante - EM122 03/02/2018 Wind 7 kts Sea state 2 - depth = 2000 m - Speed = 0 to 10 kts Noise level per channel Noise level (history)

13 Swath width control Example : L Atalante EM710 Ping mode = auto Max Opening angle = 2x70 Depth = 20 to 2000 m Mean(Bso) = -23 db The swath width predictions are issued from Kongsberg : «EM710 Product description». The coverage curves have been calculated with the following hypothesis : - three bottom types (-20 / -30 / -40 db) - noise level = 40 db - Opening angle = 2x70

14 Patch test The aim -> to detect any fine misalignment between Multibeam and motion sensor Example : roll calibration L Atalante EM122 / Phins 2 Feb 2018 Globe SW Corr = 0 Corr = -0.04

15 Accuracy testing on test areas Example : Thalia EM2040D 300 khz Renard test area (Bay of Brest) depth = 20 m Bathy (0.5 m) Bathy statistics (standard deviation) 15

16 Accuracy testing - test areas Example : Thalia EM khz Renard test area (Bay of Brest) depth = 20 m Seabed image Backscatter statistics (mean BS)

17 Positioning accuracy testing Example : Thalia EM2040 Camaret (Bay of Brest) depth = 20 m DRMS = 0.15 m σx= 0.12 m σ Y= 0.08 m DRMS = 0.15 m

18 Genavir Quality assurance tools From data acquisition to data base Before the cruise - Metrology Sensor location database - Alice checklists before the cruise During acquisition - Quartao real time QA SW After the cruise - Susanne Survey data status monitoring - Tinars post processing QA Information distribution - Madida documentation data base

19 Metrology : sensors location and orientation Metrology is a table maintained by Genavir. It provides : - Location and orientation of the sensors in the vessel reference coordinates system - Waterline height - Equipment installation parameters Origin of the data : dry docks surveys and patch tests

20 Alice : pre-cruise checklist Alice is an application used to assist the electronic officers during the pre-cruise checklist : - consistency checks on the sensors before the cruise - tests on the sensors and the connections between sensors

21 Quartao : real time QC Quartao is an application used to assist the operator in real time : - Time series display (navigation, attitude, vertical depth, sound velocity, swath width ) - Comparison between devices, statistics computation - Alarm messages in case of suspicious data

22 Susanne : cruise data management Susanne is a tool to assist the quality control staff to check the data flow between the vessels and our national data base (Sismer). It is a data base dedicated to cruise data status monitoring : - where is the data? - what about the completeness and the integrity of the data? - have the QA operations been completed?

23 Tinars : Post processing QC.all /.wcd files Tinars report (.html file) Fully automatic process (no operator intervention) The aim is to have just after the cruise : - a detailled summary of the survey - some basic quality indicators

24 Tinars report : installation parameters - Reports the SW versions and the installation parameters at the end of the cruise Tinars report (.html file) - Compares the actual parameters with the reference (metrology data base)

25 Tinars report : data view Data plots (mainly time series) : - runtime parameters : ping mode, opening angle - bathy : vertical depth, swath width, quality factor - backscatter : BSo, BSn - water column : mean amplitude before the first return of the bottom - Sensors : navigation, attitude, sound speed, time synchro

26 Tinars report : quality control For each ping, basic estimation of the quality of : - multibeam data : depth, backscatter, water column - sensors : navigation, attitude, sound velocity - Tinars quality criteria : 0 : untested / 1 : good / 2 : out of stat / 3 : doubtful / 4 : false / 9 : missing For example : If Surface SV SV Profile > 3m/s : Sound velocity is 3 (doubtful)

27 Madida : EDMS (Electronic document management system) Madida is a database accessible to the fleet users (web site) It is dedicated to provide with information on the equipment : - general information : technical specifications, documentation, configuration - an operational history : maintenance reports, patch tests results, data analysis reports Access by equipment type Acces by vessel Acces by cruise

28 Madida : equipment documentation Description of the system : Installation, specifications, performances (DINES) Kongsberg documentation (operator, installation, maintenance) Sensors interconnections Genavir documentation (operation and maintenance cookbooks) Data format description (.all,.kmall )

29 Madida : cruise reports For each cruise : A short report of the survey operations (results achieved, difficulties, shortcomings ) with attached documents : - Data analysis - Patch tests results - Transducer tests - Tinars report -

30 Conclusion : - Everybody agree that QA is important, while it does not cost any money or any time But : Is the director ready to pay more QA guys? Is the chief scientist ready to survey cross check lines?

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