Summary of Contents for IMCA Mini RadaScan
- Page 1 Mini RadaScan Microwave Radar Sensor for Dynamic Positioning Operations IMCA M 229 October 2015...
- Page 2 Asia-Pacific, Central & North America, Europe & Africa, Middle East & India and South America. IMCA M 229 This report has been prepared in order to give IMCA members an overview and review of the Mini RadaScan position reference sensor as used within dynamic positioning applications.
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Page 3: Table Of Contents
Responders ................................11 Operation ......................13 Dashboard ................................13 Multiple Sensor/Multiple Target Operation ....................14 Mini RadaScan Interoperability and Compatibility ..................14 Servicing and Maintenance ................. 16 Software Upgrades .............................. 16 Recycling and Disposal ............................16 10 Applications ......................17 11 Operational Experience .................. -
Page 5: Preface
This 4 5 6 7 document describes the Mini RadaScan product, which is part of the range of microwave relative positioning systems offered by Guidance Marine (see www.guidance.eu.com). IMCA has published IMCA M 209 – RadaScan microwave radar sensor for dynamic positioning operations. This document provides an overview of the Mini RadaScan system. -
Page 6: Glossary Of Terms
Reflection RF signal received by the sensor from the responder Responder Purpose built hardware unit mounted on a structure, which retransmits a modulated version of the signal it receives from a Mini RadaScan sensor Radio frequency Received RF signal Series1... -
Page 7: Overview
Mini RadaScan has the same friendly and familiar user interface as RadaScan. In the rest of the document, the term sensor will be used to refer to the Mini RadaScan unit unless stated otherwise. -
Page 8: Components
Components A Mini RadaScan system consists of three main components: a sensor unit for the detection and processing of reflections; a responder(s) unit, which reflects the signal from the sensor; a marine computer used to configure and control the sensor using the dashboard software. -
Page 9: Features
Responder location must be selected to ensure line of sight is maintained throughout the operation; requires the use of manufacturer’s own responders; like all microwave based sensors, sea reflections can cause problems in still conditions if the installation instructions are not followed carefully. IMCA M 229... -
Page 10: Installation
Installation Sensor Wiring Diagram The Mini RadaScan installation cable routing is shown in Figure 2. Figure 2 – Mini RadaScan components cable routing Sensor Placement Sensor placement varies with each application therefore the information hereafter is provided as a general guideline. -
Page 11: Responder Placement
This change requires service access and should be carried out by trained personnel during installation. In multi-target tracking mode, the DP system may require that the reported heading is aligned with the on-board gyro(s). This must be done through the Mini RadaScan user interface repeated prior to commencing any DP operation. 6.4.3... -
Page 12: System Design
System Design Sensor Properties Figure 4 shows the internal components of the Mini RadaScan sensor. Figure 4 – Mini RadaScan dome (left); base (centre); rotor and base (right) There are three main modules in the sensor. The rotor includes: receive (Rx) and transmit (Tx) antenna arrays;... -
Page 13: Measurement Principles
By measuring the beat frequency within a few Hz and compensating for the Doppler shift, the Mini RadaScan sensor is able to measure the range with great accuracy. However it should be noted that the sensor only reports the range from the sensor to the responder and not the horizontal distance to the structure (see Figure 6). - Page 14 It represents a fixed reference point (reference bearing) used to provide a consistent relative bearing measurement. The convention is that the bearing reported by the sensor shows 0º when the antenna is facing the connection panel and increases in a clockwise direction. IMCA M 229...
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Page 15: Responders
The algorithms use gating and validation functions and do not alter the data transmitted to the DP system. It is important for the Mini RadaScan to provide unfiltered measurements to avoid adding any unnecessary lag or delay in the DP control loop. Any filtering/smoothing on the data should be carried out by the vessel DP system if required. - Page 16 It is therefore important for personnel not to alter the position of the responder once installed and it is recommended that a notice to this effect is posted next to the responder. IMCA M 229...
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Page 17: Operation
The Mini RadaScan blanking zone is configured once during the installation and determined by the field of view where responders can be observed by the sensor (i.e. not obstructed by the vessel structure or any other metallic surface). -
Page 18: Multiple Sensor/Multiple Target Operation
Mini RadaScan data. In order to enhance safety during operations, slave consoles are only able to view the current status of the sensor and are unable to gain service access, start tracking or change the blanking zone. - Page 19 Figure 12 – Target devices: transponder (left); responder (right) When using multiple targets, because of the differing modulation types, certain rules must be adhered to. A comprehensive guide to the differences between these targets is available. 94-0271-4-A RadaScan Series 2 Responder Buying Guide.pdf IMCA M 229...
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Page 20: Servicing And Maintenance
Guidance Marine customer support team (customerservices@guidance.eu.com). Both the Mini RadaScan sensor firmware and the dashboard can be upgraded in the field using a USB memory stick or by transferring release files on the local network (e.g. marine computer). The two- step procedure involves: ... -
Page 21: Applications
10 Applications The Mini RadaScan sensor is built on the success of the larger RadaScan sensor. Although both products are in operation across a number of marine applications (Figure 13), the smaller footprint and mounting requirements of the Mini RadaScan has expanded the range of applications to smaller vessels. -
Page 22: Operational Experience
Artemis. The high transmit power (typically kW) usually associated with X-band radars means that it is important for the Mini RadaScan sensor to be located in a position or shielded so that other radar signals cannot interfere with it. - Page 23 0.125 m. At 200 m the tangential position will be accurate to 0.5 m. radial radial tangential tangential 0.25m radial radial tangential tangential 100m 0.25m radial tangential tangential 200m 0.25m Figure 15 – Error mode IMCA M 229...
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Page 24: Responder Angle Of Incidence
The natural tendency for any measurement system is for the errors to increase as the signal power decreases and Mini RadaScan is no exception. The Mini RadaScan sensor monitors the signal to noise ratio of the reflection. When this falls below a threshold, the measurement is suppressed and the fix is not supplied to the DP system. - Page 25 The geometry and environment are key to understanding the performance of a microwave radar system such as Mini RadaScan so tests done on land at about 2 m above the ground are not a good indication of the accuracy which is achievable in typical operations at sea.
- Page 26 Figure 19 – Accuracy scatter plot – Standard deviation: 0.230 m Figure 20 – Accuracy scatter plot – Standard deviation: 2.06 mrad Both range and bearing errors are quite a lot larger than in the most normal operating cases. This is nearly all due to sea reflection. IMCA M 229...
- Page 27 In a comparison with an alternative sensor (e.g. GPS), timing and other registration errors dominate over Mini RadaScan measurement errors. We can apply a high-pass filter which has unity gain for white noise while attenuating the wave motion. This gives us an upper bound on the standard deviation of the range and bearing measurements.
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Page 28: Frequently Asked Questions
No, not if the installation is carried out as instructed. Care must be taken to ensure that Mini RadaScan is not installed at the same horizontal level as the X-band radar. The recommended level separation distance is at least 3 m. - Page 29 7. Can Mini RadaScan be used in the proximity of personnel? Is it safe? Yes. Mini RadaScan is a local position reference sensor and only outputs low power transmission of the order of a few watts. The minimum safe distance is contained within the radome. There is no safety risk to personnel working on the Mini RadaScan equipped vessel or on the target installation.
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Page 30: Operational Experience
11.6 Operational Experience IMCA has received from its members favourable feedback on this system with accuracy down to 0.5m being reported. It has been described as flexible, reliable, accurate and easy to set up. Particularly noted were the good vertical angle and the acquisition range from 400 up to 1000m making it suitable for setting up on DP outside the 500m zone. -
Page 31: Specifications
85 to 264V AC 45-65 Hz 5A Marine computer TCP/IP over ethernet 100 Base-T DP system Serial over RS422 Supported DP manufacturers Kongsberg GE Energy (Converteam) Marine Technologies Rolls-Royce Navis Beier Radio Praxis Supported DP telegrams formats NMEA0183R (IEC 61162-1) NMEA0183P (IEC 61162-1) IMCA M 229... -
Page 32: Responder Specifications
Floating design and tested for immersion up to 1m Responder Dimensions Dimension 170 x 305 x 128 mm Weight 5 kg Dimension (boxed) 480 x 380 x 210 mm Weight (boxed) 11 kg Mounting Brackets Responder Compliance ATEX, UL certified IMCA M 229... -
Page 33: References
– Guidelines on installation and maintenance of DGNSS-based positioning systems Guidance Navigation Ltd, 94-0138-4 Mini RadaScan Operators Guide, UK Guidance Marine Ltd, 94-0396-4 Mini RadaScan (Dashboard) Installer's Guide, UK Skolnik MI, 1981, Introduction to Radar Systems, McGraw-Hill Book Co., Singapore 94-0271-4-A RadaScan Series 2 Responder Buying Guide Simon Kingsley and Shaun Quegan, Multipath, Understanding radar systems, section 7.4, Feb 1999, SciTech...
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