Survey Equipment
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LGBX SERIES Differential GPS Receiver
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 DGPS Receiver |
OMNISTAR System Overview The NAVSTAR Global Positioning System (GPS) is a satellite positioning system developed and operated by the United States Department of Defence. The world has free access to this GPS service; however the accuracy has been downgraded so that user can only expect to be within 100 metres of the true position 95% of the time using single GPS receiver. In order to the inadequate accuracy, differential GPS is applied (DGPS) to improve their accuracy. Fugro has setup a worldwide system of GPS reference stations. Differential correction are transmitted every second from all reference station to the Network Control Centre (NCC) at Perth, Western Australia, which operates 24 hours a day, 365 days a year. These corrections are uploaded to a communication satellite, which transmits the corrections to LGBX GPS Receiver in a standard correction format (RTCM). The system network reference stations are able to give an accuracy of 1 – 2 metres . |
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ODOM ECHOTRACK Survey Echo Sounder FEATURES
The Bathy-500 Electronic Survey Instrument used to generate precision chart recordings and digital data output. Technologically sophisticated, utilizing modern, microprocessor based electronics and a thermal chart recorder mechanism. igital processing enables the instrument to offer fully automatic bottom digitising capabilities. When interfaced with a NMEA 0183-compatible position sensor, the echo sounder provides complete, integrated hydrographical survey environment. Performance
Acoustics
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TSS-SG BROWN Gyrocompass MERIDIAN FEATURES
The Meridian gyrocompass is suitable for the ever-changing needs of a modern integrated navigation bridge system. This includes highly accurate performance with low cost of ownership and system flexibility. Due to the Meridian's small size and fast settle time of less than 45 minutes, there is no limit to the type of vessel for which it is suitable. The versatility and flexibility of the Meridian Gyrocompass can be clearly demonstrated with the remote control unit option which is supplied with the gyrocompass system. This gives freedom for the operator to install the main unit in the most convenient location whilst installing the remote control unit where it can be seen and regularly used. The heart of the Meridian Gyrocompass is the element, which is a dynamically tuned gyroscope (DTG). The DTG is a high precision technology which, due to its size, accuracy, reliability and shock resistance is used in many different applications. With a standard connection to GPS, Loch and the acceptance of very fast rate of turn (up to 200° per second), the heading is very stable and the compass can be installed on vessels of any size. The DTG is a maintenance-free dry element with a mean time between failure of 30,000 hours.
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ULTRA-SHORT BASELINE - USBL
FEATURES
GENERAL DESCRIPTIONS The Ultra-Short-Baseline (USBL) acoustic positioning method, also referred to as Super Short Baseline (SSBL), involves measuring the range and bearing from a vessel based transceiver to a single, subsea transponder. The seabed transponder which may be mounted on a mobile target such as an ROV or on a fixed target such as a seismic cable ground station, is initially positioned using data from the ship's GPS. The USBL system then provides a range and bearing estimate of the transponder relative to the ship's position. Range is calculated by measuring the time taken from sending a transponder interrogation signal to receiving its reply. Bearing is derived by comparing the small differences in the time of arrival of the reply signal at each receiver element within the transceiver. Such small delays (microseconds) are analysed as 'time-phase' differences and this data processed to provide a best fit solution. Because there are more than three receivers in the transceiver head, the redundant information can be used to get a measure of consistency and therefore quality of the position fix. DYNAMIC POSITIONINGOne of the main applications for USBL is as a position reference input for vessels fitted with a dynamic positioning (DP) system.. By deploying a transponder on the seabed and using the USBL system to calculate its relative position, a ship's DP computer can use the information to hold the vessel in the same position, on the same heading whatever the disturbing forces from wind, current and wave action. Operationally, the USBL method is very efficient as acoustic positioning can commence as soon as a transponder has been deployed in the water. At the core of the Sonardyne’s USBL system is the under hull acoustic transceiver and Navigation Processor. USBL TRANSCEIVER The innovative design of the USBL transceiver means that unlike other more complex systems, there is no need for an expensive mechanical tracking head. By providing near hemispherical acoustic coverage below its fixed deployment position, the transceiver is able to interrogate reference transponders and mobile beacons whatever their direction from the vessel.
USBL Transceiver
NAVIGATION PROCESSOR The Navigation Processor commands the transmission of acoustic signals from the transceiver to the transponders, decodes the data received back and formulates the appropriate telegram to pass to the DP desk. The unit also processes signals from VRUs, Gyro Compass' and (D)GPS. The standard operator interface consists of a 1 7" rack mountable colour monitor with integrated keypad. This facilitates system initialisation, whereby job specific parameters can be changed and positioning tasks monitored. Alternatively, the USBL display can be integrated within a customer's DP console.
Navigation Processor
TRANSPONDERS Sonardyne USBL is compatible with the vast majority of Medium Frequency (MF) transponders that are currently in use world-wide including Sonardyne's own 'COMPATT' transponders and new Super Sub-Mini which can be used to position ROVs and towfish. Options available with Sonardyne transponders include high power transducers, acoustic release mechanisms, depth rating to 6,000 metres and a choice of battery packs depending on length of deployment and anticipated interrogation intervals.
Transponders
Note: Although more convenient to install, a USBL transceiver requires careful adjustments and calibration. The stability of the acoustic data is dependent on the ambient noise and can be 0.2% of slant range when suitably accurate vertical reference units and gyros are interfaced to the Navigation processor. The overall system accuracy will be dependant upon the quality of these external sensors.
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TIDE GAUGE Model 740 Portable Water Level Recorder FEATURES
SPECIFICATION Transducer
Range
Accuracy
Calibration
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 Water Level Recorder |
CM800 SIDESCAN SONAR SYSTEM FEATURES
The CM800 and NMEA 0183 navigation data interface comes as a standard package of this, also allows the operator to enter the tow fish layback. The geographical position of any object is available just by pointing at it with the cursor. Furthermore, the cursor can also be used to directly measure the dimensions of an object, including its height.
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KVH SAILCOMP 103AC Digital Compass/Nav Repeater FEATURES
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MAGNETOMETER SURVEY GA052Cx/GA-72CD FEATURES
The GA-52Cx and GA-72Cd Locators detect the magnetic field of iron and steel objects and energized power lines. Both provide audio detection signals that peak in frequency when the locator's tip is held directly over the target. The GA-72Cd has the option of nulling or peaking.
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SIMRAD HS50 HEADING SENSOR FEATURES
Simrad HS50 is a GPS compass that provides true heading output with position, velocity and rate of turn information in addition. This product replaces several vessel instruments with one compact navigation package; gyrocompass, GPS system, speed log and Rate of Turn (ROT) indicator. The HS50 requires no scheduled maintenance or re-calibration. The system offers flexible configuration of the output variables and interface setup, depending on the vessel and application. It is easy to operate, install, and align.
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DREDGE HEAD DEPTH INDICATOR With a constant flow of air down a hose pipe the ‘back pressure' due to the head of water, can be measured, digitised, displayed and output to the HYDROpro computer software. The Control head requires regulated air flow. The air is input and the internal lead has a T-junction with the flow feeding into a plastic hosepipe. At the other end of the T junction there is a precise pressure transducer which produces a 4-20 ma current corresponding to 1 to 3 atmospheres pressure (bars) – this transducer is decided upon and time of order but is typically for 20m depth (2 bar). The signal from the pressure transducer is passed to the Analog to Digital system, which converts it to an average period. A constant depth measurement can be added, during field calibration time, as the hosepipe cannot be feed to the actual cutter depth in most cases.
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SUB BOTTOM PROFILER A Bubble Pulser, model SPR-1200 seismic profiling system operates at 200 joules and 80 milli-second sweep speed fires rate at 100 milli-seconds will be used. The bubble pulser source will be towed at 14 metres behind the navigation antenna. Seismic data will be received via string of 8-element hydrophones towed, at 14 metres behind the antenna, parallel to the bubble pulser source. The TSS will amplify the seismic signals. TVG. Amplifier and filter via the kronhite filter with a setting of low and high band pass of 700-3000Hz. Seismic records will be produced as hard copy on an EPC graphic recorder.
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VAN DER VEEN GRAB SAMPLER
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DIRECT READING CURRENT METERING
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TOPCON GTS-230N ELECTRONIC TOTAL SOLUTION FEATURES
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Total station engineered for top performance at any job site. With rugged physical enhancement, the Topcon GTS-230N is an undemanding instrument even under the most demanding conditions. Enhanced technology assures accuracy and efficiency under any work condition. Topcon GTS-230N is outfitted with versatile software that enhances any surveying project. Specification: Topcon GTS-230N
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TOPCON AT-G4/G6 AUTOMATIC LEVEL Levelling Accuracy FEATURES
Standard deviation for 1 km (1 mile) double – run levelling is 2.5mm (0.013ft)
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