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4DVib

Remote inspection of structures

A survey system that uses interferometric radar technology to capture high-frequency displacement and vibration data

The 4DVib solution from Sixense is a remote structural inspection system that harnesses interferometric radar technology to capture high-frequency displacement and vibration data without the need for physical access to the structure. Designed for situations where traditional contact-based instruments are impractical or unsafe to install and commission, 4DVib simultaneously monitors multiple points on a structure to deliver precise movement measurements and insights into vibrational behaviour. With measurement accuracy down to just a few microns under optimal conditions, it provides an exceptionally detailed view of how structures respond to dynamic loads and environmental influences.

Sixense - 4DVIB
Sixense’s 4DVib solution is a non contact movement and vibration monitoring solution

Located facing the target structure, the 4DVib unit emits frequency-modulated electromagnetic waves that allow it to differentiate between points based on their distance and capture their motion over time. This interferometric approach enables the system to record structural displacement, vibration frequencies, and natural modes at very high sampling rates — all from a safe distance and without interfering with ongoing operations. The technology’s ability to measure both static and dynamic responses makes it invaluable for characterising structural behaviour under normal conditions as well as during stress events.
 

SIXENSE 4DVib remote inspection of structures

4DVib is the ideal solution where there is a requirement to assess the movement and vibration characteristics of critical infrastructure, including bridges, towers, stay-cable systems, and other complex structures. It supports structural behaviour characterisation, serviceability verification, comfort analysis, seismic resistance evaluation, and acceptance testing — all the while removing the need for physical sensor installation on the structure(s) itself. By combining cutting-edge radar data with Sixense’s expertise in interpretation and simulation, 4DVib delivers timely, actionable insights that enhance safety, optimise maintenance planning, and reduce monitoring costs.

The 4DVib solution gives you:

Displacement measurements using 4DVib

The 4DVib unit is set up facing the structure to be inspected.

The 4DVib unit measures the distance between itself and the inspected structure at very high frequency.

Multiple points of the structure are monitored simultaneously and differentiated automatically based on their distance to the 4DVib unit. Measurements are therefore made without the need to access the structure, and can be made with or without dynamic stress.

Under optimum conditions, measurements are accurate to between 2 and 3 microns. High-frequency movement measurements make it easy to calculate displacement velocities (vibration in the same way as a geophone), and the natural frequency modes of the structure.

4DVib and its applications

  • Structural behaviour characterisation
  • Structural fitness for service verification
  • Comfort measurements
  • Structure acceptance measurements
  • Earthquake resistance characterisation
  • Cable / Stay tension measurement

Principle of operation

How interferometric radar works:

The radar unit emits frequency-modulated electromagnetic waves that enable target points to be differentiated on the basis of their distance from the device (1 point every 75 cm).

Differential interferometric analysis of the return signals calculates distance variations with a field accuracy of around 0.02 mm.

The added benefits of using 4DVib:

Cutting-edge expertise

developed from 20 years of experience and in-house development: the world’s leading specialist in the provision of accurate and immediately usable measurements

Measurement expertise, structural expertise, on-site intervention expertise

our teams understand your needs and understand how to provide you with the data you want

The availability of dedicated local teams

as a result of our extensive network

The proposal of an instrumentation solution tailored to the needs of the project

with the option to combine several different sensor types

Datasheet