High Precision GPS Compass

Dredging operations require significant volumes of highly accurate GPS data to ensure close coordination between numerous offshore assets. Not only do dredging companies require the location, but also the orientation of ships, which is crucial for preventing catastrophic accidents and maintaining efficiency (e.g. one degree off heading for a Trans-Atlantic journey can cost 1000s of Euros in fuel). IoT technology is becoming ever prevalent in this field, by bringing offshore assets online, dredging companies gain a new level of autonomy over their operations. This is exactly the reason why Boskalis approached SODAQ for an innovative GPS Compass solution.


  • < 1m horizontal position accuracy (STD)
  • < 0.6 degrees roll/pitch and heading accuracy (STD)
  • Concurrent reception of GPS, GLONASS, Galileo and BeiDou
  • -20 to 70°C operating temperature


Boskalis sought to develop a GPS Compass module to support their Tug Management System (TMS), which involves numerous offshore assets moving at the same time to transport heavy materials. It was crucial that the system can monitor longitudinal and lateral position, velocity, roll/pitch and heading with great accuracy. The biggest challenge with digital compasses is the magnetic interference on the point of installation. As ships are generally made of iron, the potential magnetic distortion is unknown and differentiates with weather conditions. Even if the current distortion was known, the sensors need to be calibrated frequently. For that reason the traditional magnetic compass solutions are not suitable and an alternative had to be built. After reviewing various market competitors, SODAQ was selected to take on this challenge.


To overcome the magnetic distortion the SODAQ engineering team decided to use two u-blox ZED-F9P high precision GNSS modules (interconnected over a serial interface) to provide a very accurate GNSS based position, heading and roll/pitch using the latest Real Time Kinematic (RTK) technology.

At its base it was decided to use a BeagleBone Industrial (embedded Linux board with an extended temperature range and conformal coating) to act as the core of the system. The advantage of the Linux system is the availability of many tools and the possibility to use modern languages like node.js and python3. The software is built around a message broker for MQTT messages. This makes it possible to exchange data in a very flexible way and is the key to a design that is easy to change or extend when there are new requirements. By using a read-only file system and a part of the RAM for storing temporary data, there is no degradation of the internal flash storage.

For monitoring the internals an additional temperature and humidity sensor is added to the baseboard. This baseboard acts as a mounting plate for the BeagleBone, the PoE (Power over Ethernet) and other power modules, the two ZED-F9P GNSS units and an optional communication module (e.g. Cellular, LoRa or Radio).Additionally, two Taoglas multi-band (L1 and L2) active GNSS antennas were selected to receive up to 180 GNSS channels. To display the information from the two high precision GNSS modules, there is a web interface that is showing the real-time data. Powering the unit by PoE (Power over Ethernet, 802.3at) makes it possible to connect the complete unit using just one cat5e cable, with a maximum length of 100m.

All communication to and from the unit is done by using the Ethernet connection. The IPv4 Ethernet connection can have 2 IP-addresses, a DHCP address and also a fixed address. This makes it possible to use the unit, without modification, in a network without DHCP and DNS server. There is no need to open the unit to change settings, the complete configuration is possible by the web-interface. The used IPv4 communication protocols are http, web-sockets, sockets, telnet and ssh. All hardware is selected to build a heavy-duty, long-lasting and flexible system, suitable for harsh environments. With the flexible software architecture it is possible to keep the units up to date and ready for future requirements.


At this point, 25 complete compass devices have been deployed in the field and are being used when they are mounted on the ships.
As the latest generation dual-band L1 L2 GNSS systems are used a much higher positioning accuracy is obtained than that existed before when using similar technologies. Also, the cost is significantly lower than any competing solution as well.

This project has given SODAQ enormous experience in high precision positioning, with the ZED-F9P module. Therefore, there is an ambition to apply the same technology to other high-precision positioning solutions, as well as scaling up the production and sales of the GPS Compass product.

How can we make IoT work for you?

Our experienced engineers are ready to deliver innovative low power tracking and sensing solutions for your next big operation. Please get in touch using the Get in Touch button on the bottom right, send an email to sales@sodaq.com or give us a call at +31 30 300 0301.

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Alessandro Verdiesen
Project Manager
+31 35 300 0301

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