What Is WaveRadar Rex2? A Practical Guide to multi-application Wave Measurement

What Is WaveRadar Rex2? A Practical Guide to multi-application Wave Measurement

WaveRadar Rex2 is an advanced wave measurement system developed by RS Aqua. Using radar technology, Rex2 measures wave height, wave period and sea level in real time for offshore and marine applications.

A tried and tested platform across multiple industries, it’s compact and operates at low power and has minimal export restrictions. This makes it particularly suitable for organisations that want real-time data without the use of crew which adds further to operational costs.

How does WaveRadar work?

At the heart of Rex2 is a frequency modulated continuous wave (FMCW) microwave radar, operating at around 26GHz. Mounted above the water, Rex2 continuously measures the sea surface, capturing the raw data needed to build a picture of the changing wave profile.

Choosing a system: What to look for

Choosing a wave measuring system is more than just comparing technical specifications between different products.  

Accuracy may matter, but so does:

• Installation requirements 
• Reliability in rugged conditions  
• Reducing maintenance requirements 
• How easy it is to extract data into meaningful insights  
• Hazardous zone certification 

Rex2 was developed to address these conditions.  In this guide, we explain how the system works, where it can be used and which factors buyers should examine when comparing available solutions.  

What should buyers look for in Wave Measurement systems?

 Buyers should assess measurement range, accuracy, sampling rate, data latency, durability, power consumption, installation requirements. The right wave measurement system should produce reliable, timely data in the intended environment while remaining practical to install, operate and maintain. 

Evaluate the entire measurement process, starting with measurement to processing and using the data. Systems and existing technologies need to be integrated and in some cases, this can save on costs.  

How accurate are wave measurement systems?

The accuracy of a wave measurement system depends on the sensor’s specification, its mounting position and the conditions at the deployment site. Correct positioning is essential. Obstructions, vessel movement, shielding and reflected waves can all affect the accuracy of the resulting data. 

Rex2 has a stated distance-measurement accuracy of 3 to 6 millimetres. Its performance has also been assessed against an independent wave-measurement system in operational offshore conditions. 

During trials aboard the Stena Saga in the eastern North Sea, significant wave-height data from Rex2 was compared with data from a nearby Datawell Directional WaveRider buoy operated by the Swedish Meteorological and Hydrological Institute. Regression analysis produced an R² value of 0.900, indicating a strong relationship between the two datasets, with a mean residual of 0.289 metres. 

The sensor and buoy were not measuring the same area of water, so differences in location, wave conditions and the methodology of the study did attempt to limit this effect. Even with these real-world variables, the results demonstrated a strong correlation between Rex2 and an established independent wave-measurement system.

Why does data latency matter in wave measurement?

Low data latency helps ensure that the reported measurement reflects the current sea surface. This is particularly important when wave data informs time-sensitive decisions such as crew transfers, vessel movements, berthing and equipment deployment. 

At output rates of up to 10Hz, Rex2 uses a burst data mode that carries out an upward and downward frequency sweep together. At outputs rates up to 5Hz the measurements are synchronous, meaning that the measurements are exactly evenly spaced in time. 

This technique reduces the time between averaged samples and removes the lag associated with the legacy measurement method. The result is closer synchronisation between the measured sea surface and the data output. 

What makes a wave measurement system suitable for marine environments?

A marine wave measurement system should use corrosion-resistant materials and be capable of sustained exposure to saltwater, sea spray and changing weather conditions. Relevant hazardous-area certification may also be required for offshore installations. 

Rex2 is constructed from 316 stainless steel and PTFE to provide corrosion resistance in marine environments. Its durability was assessed during a continuous deployment of more than one year at Sandown Pier, where the sensor was installed close to the water and exposed to sea spray throughout the seasons.

What’s the advised compliance rating?

Compliance is an important consideration when choosing a wave measurement system, particularly for offshore installations. Platforms and other industrial sites can contain hazardous zones where flammable gases or vapours may be present, meaning electrical equipment must meet specific safety requirements before it can be installed and operated. 

Choosing a sensor with internationally recognised hazardous-area certifications gives operators greater flexibility over where it can be deployed, while helping projects meet the safety and regulatory requirements of different regions. 

How much power does a wave measurement sensor require?

Power requirements vary between sensors, but low consumption is particularly valuable for remote or off-grid installations. Buyers should check average and peak consumption, supply requirements and whether the system can operate using batteries or renewable energy. 

Rex2 has an average power consumption of 0.4 W and a peak consumption of 1 W. It operates from a 9-36 VDC power supply. 

This low power demand makes the system suitable for installations where grid power is unavailable and energy must be supplied through batteries, solar panels or other renewable sources. 

What installation factors should buyers consider?

Buyers should consider sensor size, weight, mounting position, measurement distance, power availability and access for maintenance. Vessel installations may also require motion compensation to separate wave movement from vessel movement. 

Rex2 is compact and weighs approximately 8.5 kg without its mounting flange. Its 3-to-80-metre measurement range supports installation across a variety of fixed-platform, coastal and vessel-based mounting positions. 

The radar operates using a frequency-modulated continuous-wave sweep around a 26 GHz midpoint. This frequency band is not subject to the export controls encountered by certain 10 GHz sensors, which may simplify international deployment. 

What is WaveView Connect?

WaveView Connect software is a processing and display programme, for static or moving vessel installations. WaveView Connect uses information from a motion reference unit to compensate for vessel movement. This helps distinguish changes in the sea surface from changes caused by the vessel itself. 

What data outputs should a wave measurement system provide?

A wave measurement system should provide data in a format and at a rate that can be used by existing monitoring, navigation or operational systems. Buyers should also establish whether raw measurements require separate processing software. 

Rex2 provides a user-configurable output rate of 2 to 10 Hz. Data is available directly through RS485, with optional USB and Ethernet connections. An onboard LCD displays the real-time measurement distance, providing a quick local indication of the sensor’s status. 

WaveView Connect processes raw measurements from one or more Rex2 sensors and produces a range of deterministic, spectral and tidal parameters, including:

• Significant wave height 
• Maximum wave height 
• Wave period 
• Peak wave period