Fibre Optic Monitoring
Continuous Monitoring for Underground Cable Infrastructure
UNDERSTANDING FIBRE OPTIC MONITORING
Detecting Physical Disturbances Along Underground Cable Routes.
Underground cable infrastructure can be difficult to protect.
Power, telecommunications and other important cable routes can extend across large areas, often beyond locations that can be continuously observed using CCTV or other conventional security measures.
Cable theft, excavation, mechanical activity and other physical disturbances around these routes can result in damage and disruption. In many cases, the challenge is not simply protecting the cable itself but knowing that potentially damaging activity is taking place before the consequences are discovered.
Fibre optic monitoring provides a way to continuously monitor underground cable routes for physical disturbances. Using Distributed Acoustic Sensing (DAS), optical fibre becomes a sensing medium capable of detecting vibrations and activity along the monitored route.
This guide explains how fibre optic monitoring works, the role of DAS, the threats it can help detect and how the technology can form part of a wider underground cable protection strategy.
What Is Fibre Optic Monitoring?
Fibre optic monitoring uses optical fibre as a distributed sensor to detect physical disturbances along a monitored route.
For underground cable protection, a dedicated sensing fibre is installed alongside the infrastructure being protected. Distributed Acoustic Sensing (DAS) is then used to detect vibrations and disturbances affecting the fibre along the route. Rather than relying on individual sensors positioned at particular points, the fibre itself provides sensing along the monitored infrastructure.
For underground cables, this creates a way of detecting physical activity around routes that may otherwise be difficult to observe continuously.
Remark Group's solution can detect disturbances associated with cable theft, excavation, mechanical activity and rodent movement, generating real-time alerts when relevant activity is detected.
Why Is Underground Cable Infrastructure Difficult to Protect?
Underground cable routes present a different protection challenge from equipment located within a building, compound or other clearly defined area.
A route may extend across a considerable distance and pass through locations where continuous visual surveillance or physical security is impractical. The infrastructure itself is also below ground, making activity around the route more difficult to observe.
The risks can be deliberate or accidental. Cable theft and tampering can result in damage and service disruption, while excavation and other mechanical activity can also put underground infrastructure at risk.
Traditional security measures still have an important role. CCTV can provide visual coverage of selected areas, while fencing, access control and patrols can protect or monitor defined locations. The challenge is maintaining awareness of what is happening along the underground cable route itself.
Fibre optic monitoring addresses this gap by detecting physical disturbances along the monitored route as they occur.
How Does Fibre Optic Monitoring Work?
Remark Group's underground cable monitoring solution uses Distributed Acoustic Sensing (DAS).
A dedicated optical fibre is installed alongside the underground cable infrastructure being protected and connected to the monitoring technology.
The system sends pulses of light through the fibre. As the light travels along it, a small amount is naturally scattered back towards the source. Physical vibrations and disturbances affecting the fibre alter characteristics of this returned light.
DAS analyses these changes to detect activity occurring along the monitored route. The optical fibre therefore becomes the sensing medium itself, allowing disturbances to be detected at multiple points along its length rather than relying on individual electronic sensors positioned at intervals.
When relevant activity is detected, the monitoring system can generate an alert so that the disturbance can be investigated.
What Does DAS Mean?
DAS stands for Distributed Acoustic Sensing.
It is a fibre optic sensing technology that allows vibrations and disturbances to be detected along the length of an optical fibre. A useful way of understanding DAS is as turning the fibre into a continuous line of sensing points.
This makes it particularly relevant to linear infrastructure such as underground cable routes, where the infrastructure requiring protection may extend well beyond an individual building or compound.
What Can Fibre Optic Monitoring Detect?
The purpose of fibre optic monitoring is to identify physical disturbances around the protected cable route.
Remark Group's solution can detect disturbances associated with:
Cable Theft and Tampering
Attempted interference with underground cable infrastructure can create detectable physical disturbances. Monitoring can provide an indication of this activity while it is taking place, rather than relying solely on the resulting damage or loss of cable to reveal that an incident has occurred.
Concerned specifically about theft? Read: Cable Theft Detection: Can Attempted Cable Theft Be Detected Before Damage Occurs?
Excavation and Accidental Damage
Digging and excavation around underground infrastructure can put cables at risk even where there is no deliberate attempt to interfere with them. Physical disturbances associated with this activity can be detected along the monitored route.
Read: How Can You Reduce the Risk of Accidental Damage to Underground Cables?
Mechanical Activity
Other mechanical activity around the cable route can also create detectable disturbances and may indicate activity that could threaten the protected infrastructure.
Rodent Movement
Remark Group's solution can also detect disturbances associated with rodent movement where this presents a risk to the protected cable infrastructure.
A detected disturbance does not necessarily mean cable damage has occurred. It provides an alert that relevant physical activity has been detected so that the event can be investigated.
Where Can Fibre Optic Monitoring Be Used?
Fibre optic monitoring is particularly relevant where important underground cable routes extend across areas that are difficult to observe continuously. This can include power, telecommunications and other underground cable infrastructure across commercial, industrial and critical infrastructure environments.
Suitability depends less on the sector itself and more on the infrastructure: the cable route, its importance and the physical risks surrounding it.
The technology can be considered for both new cable infrastructure and existing underground routes where additional monitoring is required.
How Does Fibre Optic Monitoring Fit Into a Wider Cable Protection Strategy?
Fibre optic monitoring is not a replacement for every other form of security or infrastructure protection.
Different measures perform different roles:
| Protection Measure | Role |
|---|---|
| CCTV | Provides visual coverage and can help verify activity within the camera's field of view |
| Physical security | Helps restrict access to buildings, compounds and other defined areas |
| Security patrols | Provide physical inspection and a visible security presence |
| Fibre optic monitoring | Detects physical disturbances along the protected underground cable route |
The value of fibre optic monitoring is therefore not that it makes other measures unnecessary. It provides a different layer of visibility.
Where conventional measures are concentrated around specific locations, fibre optic monitoring provides sensing along the underground route between them. The appropriate combination will depend on the infrastructure, environment and risks being managed.
Can Fibre Optic Monitoring Be Added to Existing Underground Cables?
Yes. Remark Group's solution can be deployed alongside new and existing underground cable infrastructure. For new projects, monitoring can be considered alongside the cable infrastructure from the outset.
For existing routes, the current infrastructure, cable route and practical requirements for introducing the dedicated sensing fibre need to be assessed.
The fact that underground infrastructure is already operational does not therefore automatically rule out fibre optic monitoring. For a closer look at this question, read: Can Fibre Optic Monitoring Be Added to Existing Underground Cable Infrastructure?
What Should You Consider When Planning Fibre Optic Monitoring?
Fibre optic monitoring should be planned around the infrastructure and risks rather than treated as a standard installation.
Important considerations include:
The infrastructure being protected-
Which underground cables require monitoring and how important are they to the site or operation?
The cable route-
Where does the infrastructure run and what is the environment around it?
The physical risks-
Is the concern theft, excavation, mechanical disturbance, rodent activity or a combination of threats?
New or existing infrastructure-
Can monitoring be considered as part of a new cable project, or does the sensing fibre need to be introduced alongside an established route?
Existing protection measures-
What CCTV, physical security and operational measures are already in place, and where are the gaps in visibility?
Response to alerts-
How will a detected disturbance be reviewed, investigated and responded to?
The objective is to understand where visibility of the cable route is limited and whether continuous monitoring would provide useful additional protection.
What Are the Benefits of Fibre Optic Monitoring?
For suitable underground cable routes, fibre optic monitoring can provide:
Continuous route monitoring
Monitoring takes place along the protected cable route rather than only at individual security points.
Detection while activity is occurring
Relevant physical disturbances can generate alerts while the activity is taking place.
Visibility across difficult-to-observe infrastructure
Underground and linear cable routes can be difficult to monitor continuously using visual security measures alone.
Detection of deliberate and accidental activity
Monitoring can identify disturbances associated with attempted theft as well as excavation and other mechanical activity.
Deployment alongside new or existing infrastructure
Monitoring can be considered for new projects or introduced alongside established underground cable routes following assessment.
The value ultimately depends on the infrastructure and risk. Fibre optic monitoring is most relevant where greater awareness of physical activity along an underground cable route would improve its protection.
Choosing a Fibre Optic Monitoring Partner
The technology is only one part of an effective underground cable monitoring solution.
Deployment needs to take account of the cable route, surrounding environment, infrastructure being protected and physical risks that need to be detected.
A monitoring partner should therefore be able to understand the site requirements, establish an appropriate approach and support the installation and commissioning of the solution.
Where monitoring forms part of a wider protection strategy, consideration should also be given to how it sits alongside existing physical and electronic security measures.
Fibre Optic Monitoring from Remark Group
Remark Group provides DAS-based fibre optic monitoring for underground cable protection.
Our Duct Protection Fibre solution uses a dedicated sensing fibre installed alongside the protected underground cable infrastructure. Distributed Acoustic Sensing continuously monitors the fibre for physical disturbances, generating real-time alerts when relevant activity is detected.
Looking to protect underground cable infrastructure? Speak to Remark Group about your cable route, the risks you're facing and whether fibre optic monitoring could provide an additional layer of protection.
