Position Reference System

Mega-Guard DP Position Reference Systems (PRS)

Features

The following Mega-Guard DP Position Reference Systems (PRS) are available:

  • DGPS/Glonass with NTRIP (DGN-5000)
  • Hydroacoustic Position Reference (HPR-5000)
  • Taut wire Position Reference (TPR-5000)

Third party position reference systems like DGPS with IALA, Seastar or Veripos and position reference  systems based on laser and radar are supported as well.

The Mega-Guard DP system supports up to 16 different position reference systems. The final position is calculated taking into account the reliability, accuracy and weighing factor of each position reference system.


DGPS/Glonass with NTRIP

The Mega-Guard DGPS/Glonass with NTRIP (DGN) position reference system is a cost effective DGPS solution to reach sub-meter accuracy with global coverage. The Mega-Guard DGN requires a mobile internet connection (VSAT) in order to receive position corrections via the so called NTRIP protocol. In many cases the position corrections via NTRIP is a free-of-charge service. The Mega-Guard DGN includes a GPS/Glonass L1 receiver which is capable of receiving both GPS and Glonass satellites. A seperate NTRIP Workstation (client) has access to the NTRIP Broadcasters who send position corrections via the internet.

The Mega-Guard DGPS/Glonass with NTRIP consists of the following components:

  • DGPS/Glonass L1 receiver with 24 channels and including SBAS correction and external RTCM104 input receiving corrections from NTRIP Workstation.
  • DGPS/Glonass antenna with 30 meter antenna cable.
  • NTRIP Workstation with NTRIP Client software and control software for the DGPS/Glonass receiver. The NTRIP Workstation is connected to the internet via a VSAT receiver (not part of scope of supply). The NTRIP Workstation transmits position corrections to the DGPS/Glonass receiver through RTCM104 protocol. The solid state (no moving components) Workstation includes a 17" TFT Colour Graphic Screen and a Trackball and is powered by 19~32VDC.

Third party reference systems

The following third party position reference systems are often used with the Mega-Guard DP system:

  • CyScan; laser position reference system with deck unit and mirror as installed on platform.
  • RadaScan; radar position reference system with deck unit and transponder as installed on platform.
  • Fugro 9200; DGPS L1 and L band receiver for receiving Seastar position corrections via L band. Options include: IALA beacon (external), L2 and Glonass.
  • Subsea7 LD5; DGPS L1/L2 and L band receiver for receiving Veripos position corrections via L band. Options include: IALA beacon and Glonass.
  • C-Nav-1000; DGPS L1 with IALA beacon receiver.

Hydroacoustic Position Reference

The Mega-Guard Hydroacoustic Position Reference (HPR) is applied as a cost effective and highly accurate position reference system for the Mega-Guard Dynamic Positioning System (DP2 and DP3). The position of the seabed USBL Transponders are used as reference points for the ship mounted USBL Transceiver. The USBL Transceiver, MRU and Gyro are connected to the HPR Control Cabinet.

The HPR Workstation accurately calculates the relative position of the vessel taking into account the data as received from the HPR Control Cabinet.  An USBL Transponder contains a release mechanism with floating collar for recovery of the Transponder from the seabed.

The Mega-Guard Hydroacoustic Position Reference consists of the following components:

  • HPR Workstation; a NMEA-0183 relative position output is provided for connection to the Mega-Guard DP.
  • HPR Control Cabinet
  • USBL Transceiver; two versions available: 10000, 3500 and one for 1500 meter water depth.
  • USBL Transponder; various models available depending on water depth and beam width.

The USBL Transceiver can be mounted in 2 different ways:

  • Hull mounted with Gate Valve and Deployment Machine.
  • Pole mounted with Over-the-side Pole.


Taut Wire Position Reference

The Mega-Guard Taut Wire Position Reference (TPR) is applied as a position reference system for the Mega-Guard Dynamic Positioning System (DP2 and DP3). The Taut Wire Deck Winch is deck mounted at port or starboard side of the vessel. The Mega-Guard TPR is very accurate, reliable and maintenance free as it is constructed as a full electric device (no hydraulics used for the winch).

The Mega-Guard Taut Wire Position Reference consists of the following components:

  • Taut Wire Deck Winch with a 500 meter long / 6mm thick steel cable and clump weight. The clump weight is lowered to the seabed and the cable is put to constant tension. The Deck Winch includes a Taut Wire Control Cabinet which calculates the relative position of the ship taking into acount the input from the MRU.  A NMEA-0183 relative position output is provided for connection to the Mega-Guard DP.
  • Taut Wire Control Cabinet, installed at a dry location, with control electronics for the deck winch. Powered by a three phase 440VAC power supply.
  • A Taut Wire Operator Panel is installed on bridge for controlling the Taut wire Deck Winch.

Sales and service

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Contact information

Praxis Automation Technology
Zijldijk 24A,
2352 AB Leiderdorp
The Netherlands

+31 (0)71 5255 353
info@praxis-automation.com

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