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Mr. Yorihisa Suwa, of Japan Radio, presented his company's integrated system called "Total NAVIGATOR III," which uses electronic charts to add coastal and channel navigation to its navigation system. Displayed information includes:

• Navigational data - graphic coast line, depth, boundaries, dangerous zones, markers, scheduled route, ship track, other ship's track from automatic radar plotting aids (ARPA)

• Numeric data - time, ship's position, speed, total distance, course to steer, bearing and time to way point, cross track error, from metersheading, rudder angle, turn rate

Weather data - wind direction and velocity, atmospheric pressure, relative humidity, air temperature, water temperature

⚫ Hull motions - pitch, roll, metacentric height (GM), draft and trim, propeller slip ratio

• Engine data - propeller revolutions, propeller pitch, shaft horsepower, torque, main engine (M/E) loading, turbocharger revolution, M/E start air pressure, M/E temperature

The system allows the user to make an electronic chart from a paper chart, incorporating a computer with a digitizer. One electronic chart may have five mark (buoys, etc.) and seven line (coast line, depth contours, etc.) types at one time. One megabyte on a floppy disk holds a maximum of 15 electronic charts.

TECHNICAL REPORTS ON MULTI-BEAM TECHNOLOGY

Dr. Robert Tyce of the Ocean Mapping Development Center of the University of Rhode Island discussed

"Opportunities for International Cooperation in Swath Sonar Processing.” At this writing 82 swath bathymetry systems are being used world wide. The United States (29) and Japan (19) maintain the bulk of the systems, with Norway (8), Canada (5), U.S.S.R. (5), England (3), Germany (3), The Netherlands (3), France (2), Australia (1), India (1), Korea (1), and Spain (1). In the United States, recognizing the complex problems involved in integrating information from many different systems, the Defense Hydrographic Initiative was developed to deal with coordination among the Defense Mapping Agency, the Oceanographer of the Navy, and NOAA. The initiative treats three primary areas:

1. Standardization of hydrographic/ bathymetric data collection, processing/evaluation, archiving and analysis/integration.

2. Product and service identification and definition and implementation of the necessary support process.

3. Coordination of research and development (R&D) initiatives among academia, private industry, allied hydrographic offices, and international organizations as appropriate.

Implied is the development of digital products such as a Master Seafloor Digital Database (MSDDB) to include: topographic properties, man-made points, line and area features, gravity, magnetics, geoacoustic properties, and acoustic bottom properties. Dr. Tyce proposes the creation of an International Working Group that would take the following actions:

• Create regional directories of organizations and individuals involved in swath sonar processing: Organization, Name, Computer Type, Address, Phone Numbers, and Computer Mail Address.

• Combine regional directories into an international directory.

• Conduct regional meetings of working groups with agency sponsorship.

• Conduct international meetings of representatives of regional working groups with sponsorship assistance from agencies and sonar

manufacturers.

• Exchange processing software for swath bathymetry and imagery among working group members.

• Exchange swath sonar ship tracks and data through existing organizations.

Dr. Akira Asada, of JHD, presented a paper titled "New Bathymetric Surveying and Processing System Based on Sea Beam 2000." This was a discussion of the system on their new survey ship MEIYO, which begin surveying in March 1991. Navigation generally uses MX440GPS, MX4810GPS, and R-R LORAN-C in various order of priority depending on quality of the returns. This permits preparation of (1) a depth contour chart along the track, (2) a track chart, and (3) a sounding chart incorporating the navigation with the output of the Sea Beam system. JHD has modified the existing processing software and developed new programs to improve and extend the processing capability. Eventually they would like to have all processing in real time on ship board. The processing programs discussed in detail are as follows:

• Position-Fix Correction: This pro

gram is designed to remove spike errors in the fixes, to smooth meanderings produced by instability of the fixes, and to process differences in level that result from data from combinations of GPS satellites.

⚫ JMSA Uniform Format: The use of this program converts the data from the multi-beam system to a unified system. Software is available for Sea Beam 2000, Sea Beam, HS-10, HS-200, and Hydrosweep.

Erroneous Data Elimination: This program identifies and "corrects" spikes and anomalous readings based on integration of 100 shots looking fore and aft as well as right and left of the shot point, assuming that no topographic feature has only one spike datum. The program is designed to allow for complex topography near seamounts, scarps, trenches, etc. At present, processing of 100-shot points takes 18 seconds. One segment of a survey line, which corresponds to 150 MB, takes about a half day for processing.

• Contour Processing: This program translates the geographic positions to the longitude of the beam positions as the heading of the vessel usually differs from the direction on an X-Y chart. This leads to inaccurate cross track distances on a Mercator projection.

• Digital Color Printer Application: Programs written for the Pictography 2000 color thermal printer with a capacity of 2048x2560 pixels permit quality mesh map presentations of the processed soundings. With this software, three-dimensional image processing, magnitude mapping of sea bottom inclination, and direction mapping of sea bottom inclination can be produced in color coded mesh maps.

Other programs listed but not discussed include GPS Differential Postprocessing and Track Chart Processing. For the Sea Beam 2000 system programs include Contour Processing TimeSequential, Sounding Chart, Root Mean

Square (RMS) Error Calculation, RollSquare (RMS) Error Calculation, RollBias Assessment, Tidal Correction, Sound Velocity Path (SVP) Recalculation, and Sounding Accuracy Assesstion, and Sounding Accuracy Assessment. Dr. Asada pointed out that the Sea Beam system uses a mean speed of sound assumption. This would produce errors of just over 1% for depths shallower than 4,000 meters and worse than that at greater depths. He presented a series of examples showing how the Ray Curve, SVP, and Surface Layer Refraction corrections are influenced by the mean speed of sound assumption. Finally, examples were shown of the survey of the area of Mikura Seamount comparing real-time contour maps with postcruise processing (2 days). The real-time map is useful in identifying areas of poor sounding for resurvey ing areas of poor sounding for resurvey before leaving the area. The combination of the existing Sea Beam 2000 system with the error check and correction software developed by JHD is tion software developed by JHD is providing extremely high quality bathyproviding extremely high quality bathymetric information with a low failure

rate.

Continuing with the theme of error correction, Dr. Thomas Stepka of NOAA gave a paper on “An Automated Method of Detecting Errors in Beam Pointing Angles in Swath Sonar Arrays." The beam angle error is a function of the deviation about a ship's pitch, roll, and yaw axes. Conventionally, a "patch test" is run over a test area and the results are plotted by hand. However, the method requires a smooth bottom and is very labor intensive with marginal statistical significance due to the small number of points used. NOAA has awarded a contract to the TAU Corporation to develop an automated patch test analysis system. The system was delivered in August 1991. The algorithm developed (1) selects an initial estimate of pitch, roll, and yaw deviations and computes the depth for each model; (2) computes the sum of the squared differences between models at every sounding in the user-defined area

(usually several hundred); (3) estimates new biases based on old estimates and partial derivatives of the model depth function; (4) computes new models based on new error angle estimates; and (5) continues iterations until the sum of squared differences ceases to decrease ("total number of iterations is usually 5 to 12"). Results to date indicate that the system can detect pitch and roll biases "accurately and repeatedly." Similar results for yaw have not been achieved, due to, for example, the ship's gyro input not sufficiently accurate and tests need to be run on steeper slopes.

"Sea Beam System of the Ocean Research Institute, University of Tokyo" was the paper given by Dr. Kensaku Tamaki. Sea Beam mapping cruises on the HAKUHO-MARU have been made to the Nankai Trough (1989), the Japan Trench (1990), and the Manus Basin (1991). Future cruises are planned for the Ayu Trough (1992), Kuril Trench (1992), and the Mid-Indian Ridge (1993). The presentation was mainly on the data handling systems. Data processing was managed by a fourchannel serial (RS232-C, 9600 bps) interface inside a DG S/140 minicomputer. The real-time mapping system is operated by a Yokogawa-HewlettPackard 350 SRX workstation with 24 MB used for processing. Data from the Magnavox Series 5000 used for shipboard data (navigation, etc.) and from the Sea Beam system are stored in a 300-MB hard disk. All data files are accessible from shipboard workstations via an optic fiber cable Ethernet LAN. Formats and byte addresses for the various parameters are given in several detailed tables.

Dr. Katsutoki Matsumoto, of the Metal Mining Agency of Japan, presented for his colleagues Kouhei Maeda, Madao Saito, and Nobuyuki Murayama all of the Deep Ocean Resources Development Co. Ltd., a paper titled "Equipping R/V HAKUREI-MARU No. 2

with MBES and Test of MBES. MBES refers to Multi-Beam Echo Sounder, which was the Krupp-Atlas Hydrosweep. The HAKUREI-MARU is designed and equipped for exploration for mineral resources on the deep seabed. Thus the multi- and narrow-beam systems were tested with respect to their suitability for ocean mining surveys. For surveys deeper than 5,500 meters, the ship was modified to reduce underwater noise. Improvements were to install a high skew propeller and to add stern tunnel fins, auxiliaries, and pumps in the engine room and pipe lines were made vibration-proof in support. This reduced the noise level 12 dB at 12 knots and 26 dB at 8 knots. Tests in the spring of 1991 in the Izu-Ogasawara (Bonin) Trough of a 30-kHz narrow-beam echo sounder and the 15-kHz Atlas Hydrosweep showed good results in 9,000 meters thanks to the noise reduction procedures. In returning to port, the Hydrosweep system was used to survey the complicated sea bottom off the Boso Peninsula and was successful in producing a real-time seafloor contour map.

Dr. Norman Cherkis of the U.S. Naval Research Laboratory discussed "Multi-Beam Echo Sounding and SeaMARC II Acoustic Imaging in the Norwegian Sea." The R/V EWING, of the Lamont-Doherty Geological Observatory, during the summer of 1990 took about 22,000 km of track line over the Aegir Ridge in the North Atlantic. This cruise combined data from the Hydrosweep multi-beam echo sounder with the SeaMARC II acoustic imaging system. Data from the ongoing survey were transmitted by satellite back to land every third day, where backscatter analysis was done. This was done to determine the amount of acoustic energy absorbed by the sediment which, in turn, was used to model sedimentary features and infer processes, particularly in areas where there was no seismic profiling information. The photographically merged data from the two

systems proved a successful way to interpret structural lineations and other fine-scale features.

Industry representative Mr. Hideharu Morimatsu of Furuno Electric Co., Ltd. presented "Development of Multiple Narrow Beam Echo Sounders for Shallower Waters." Two systems, the HS-200 II (150 kHz, maximum depth 600 meters) and the HS-500 II (500 kHz, maximum depth HS-500 II (500 kHz, maximum depth 50 meters), and the attendant software package "Sea Map PC" were discussed. The systems have been used in several practical situations including not only primary bathymetric surveying but in confirming locations of objects placed on the seafloor. In this example, an array of artificial fish shelters, each a 3-meter cube, was found not to be placed as planned. The area surveyed was 400 by 500 meters with an average depth of 130 meters varying about 5 meters. At 5 knots it took 200 seconds to survey with about 400 pulses emitted. Processing of the data for a bathymetric map, using their software with a conventional PC, is rapid. For a 40-minute survey and 4,440 transmissions, it took 22 minutes to initially process, 13 minutes to generate the grid, and 13 minutes to plot the chart on an X-Y plotter.

Mr. Shin Tani of JHD, substituting for Dr. Takeshi Matsumoto of the Japan Marine Science and Technology Center (JAMSTEC), showed a "Comparison of the Bathymetric Data of HS-10 Multi Narrow Beam Echo Sounder with Sea Beam Data." Two surveys of with Sea Beam Data." Two surveys of the Japan Trench at a depth below 6,000 meters, one by the R/V 6,000 meters, one by the R/V HAKUHO-MARU with a Sea Beam system in 1990 and the other by the M/S YOKOSUKA in 1991, were used to compare the systems. The chart produced from the HS-10 system plots about 50 meters deeper than that from the Sea Beam bathymetry. Small-scale features at such depth seem to be a problem for the HS-10 system, as apparent false features are generated

as well as nonrecognition of established features. In general, short-wavelength topographic features clearly present in Sea Beam are reduced in the HS-10 reconstructions. Some of the differences may be explained by differences in the gate settings with cross track "noise" responsible for artifacts in the HS-10 system.

The final presentation was given by RADM Andreasen, substituting for CAPT John C. Albright of NOAA. The paper, "Use of Differential GPS at the National Ocean Service," described the efforts to develop and test a system for vessel positioning that improves the positions available for either the Standard Position Service (SPS) or the Precise Position Service (PPS) provided by the Global Position System (GPS). The differential system uses a static GPS receiver at a known location to determine the satellite range correction for each satellite as it passes by. These corrections are transmitted to the user for the position calculation at sea. The differential GPS (DGPS) corrections change slowly so that a transmission of one per 20 to 30 seconds is sufficient. The improved satellite range information results in a longer survey window and thus use of low angle satellite passes, which formerly were unacceptable. Initial tests of the technique were in Hawaiian waters using a commercial COMSAT earth station facility. The corrections were eventually sent to the Pacific Ocean Region (POR) satellite where they were received by the survey ship DISCOVERY. A 19-hour test of the system while the ship was docked showed an average agreement of 5.8 meters. A second test at about 175 nautical miles at sea, checked with Mini-Ranger lines of position, showed an average agreement of 7 meters. Technical problems with the transmission terminals and failure of the Pacific Ocean Region satellite produced a downtime of 50%. To avoid such non-DGPS related failures, a joint NOAA-U.S. Coast Guard system where

radio beacons are used promises to be useful to within 300 nautical miles of the coast line. The accuracy of this system is thought to be about 10 meters or 2 standard deviations. The radio beacon system was tested in July 1991 on the RUDE using the Montauk Point, New York beacon. Here the MiniRanger and the DGPS positions agreed to about 5 meters. Radio beacon systems are planned for operations in the Gulf of Mexico near Corpus Christi and near Freeport, Texas, and for Cape May, New Jersey, and Cape Henry, Virginia, as well as the Montauk Point beacon. In addition, a “fly-away" DGPS system is being tested. This system is composed of two GPS receivers and a VHF radio data link. The system was tested successfully in Lake Michigan on a 22-foot launch. It is considered that the DGPS systems either fixed or fly-away will become the primary positioning system for mapping, especially in near-shore areas of the EEZ.

Pat Wilde joined the staff of the Office of Naval Research Asian Office (ONRASIA) in July 1991 as a liaison scientist specializing in ocean sciences. He received his Ph.D. in geology from Harvard University in 1965. Since 1964, he has been affiliated with the University of California, Berkeley in a variety of positions and departments, including Chairman of Ocean Engineering from 1968 to 1975 and Head of the Marine Sciences Group at the Lawrence Berkeley Laboratory (1977-1982) and on the Berkeley campus (1982-1989). He joined ONRASIA after being the Humboldt Prize Winner in Residence at the Technical University of Berlin. Dr. Wilde's speciality is in paleooceanography and marine geochemistry, particularly in the Paleozoic and Anoxic environments. He maintains an interest in modern oceanography through his work on deep-sea fans, coastal and deep-sca sediment transport, and publication of oceanographic data sheets showing the bathymetry with attendant features off the West Coast of the United States, Hawaii, and Puerto Rico.

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