Short answer
Distributed Acoustic Sensing (DAS) turns a single fiber optic cable running along a pipeline, power cable or fence into thousands of virtual microphones. One interrogator typically covers tens of kilometres and reports leaks, excavation, illegal tapping, pig passage and fence climbing in real time, with location. DuyuSense develops these systems using its patented DAS signal-processing method.
How does DAS detect pipeline leaks?
DAS detects leaks by picking up the acoustic noise that pressurised fluid makes as it escapes through an opening, along with the change in vibration around the pipe. Each event reaches the control room with a location accurate to within metres.
Distributed Temperature Sensing (DTS) is a strong complement for leak detection: escaping gas cools the surrounding soil through expansion, while liquid and hot-product leaks warm it. Running DAS and DTS on the same fiber bundle lets the acoustic and thermal signatures confirm each other.
- Acoustic leak signature: continuous, broadband flow noise
- Tracking of negative pressure wave effects along the fiber
- Cross-checking with DTS cooling or warming anomalies
How can excavation, third-party interference and illegal tapping be prevented?
DAS captures the vibration that excavators, picks, shovels and drilling equipment transmit into the ground before any damage occurs. Response teams can be dispatched while digging is still metres away from the pipe.
Illegal tapping attempts produce a distinctive acoustic signature because of mechanical work close to the pipe wall. Vehicle approach, footsteps and manual digging along the right of way (ROW) are reported as separate classes.
- Machine digging versus manual digging
- Drilling or cutting attempts on the pipe wall
- Vehicle and pedestrian activity in the ROW
Can DAS track pigs and ground movement?
Yes. DAS tracks a pig (pipeline cleaning or inspection tool) through the periodic impacts it makes crossing girth welds, showing its position and speed continuously. A stuck pig can be located directly.
In landslide, subsidence and fault zones, ground movement appears as low-frequency strain change on the fiber. For slow, long-term deformation, Fiber Bragg Grating (FBG) strain sensors provide calibrated, high-sensitivity measurement at critical points.
How is DAS used for perimeter intrusion detection (PIDS)?
A DAS-based perimeter intrusion detection system (PIDS) detects climbing, cutting, walking, digging and vehicle movement through fiber cable attached to a fence or buried along a boundary. Because the cable carries no electronics or power, field maintenance is minimal.
Typical sites include airports, power plants, substations, data centres, military facilities and land borders. When buried, the system is invisible, which makes it hard for an intruder to spot or defeat.
- On fences: climbing, cutting, shaking
- Buried: walking, running, digging
- Vehicle detection and vehicle type classification
- Camera integration: automatic slew to the alarm location
How are buried power cables and high-voltage lines monitored?
Buried power cables are monitored with DAS through fibers laid alongside the cable or integrated into it. Excavation and third-party interference along the cable route are detected before they turn into faults.
On overhead lines, the OPGW fiber in the earth wire can be used to monitor wind-induced vibration, icing effects and impact events. Combined with DTS, cable temperature and loading can be tracked over the same infrastructure.
How do event classification and false-alarm reduction work?
Event classification works by extracting time, frequency and spatial features from the raw DAS signal and feeding them to signal-processing and machine learning models. The goal is to separate harmless sources such as traffic, rain, wind and animals from real threats.
False-alarm rate is closely tied to signal-to-noise ratio (SNR). DuyuSense's patented DAS signal-processing method uses noise reduction to improve spatial resolution and SNR, with the aim of higher event-detection accuracy.
- Feature extraction: spectral energy, duration, spatial extent
- Classifiers trained on site-specific labelled data
- Zone-based sensitivity and alarm thresholds
- Event correlation to suppress recurring nuisance sources
How is DAS deployed on existing fiber infrastructure?
In most cases DAS runs on a spare (dark) fiber in the telecom cable already laid along the pipeline or power cable route. One interrogator typically covers tens of kilometres, with single-channel range often cited around 40-50 km.
DuyuSense offers engineering support from feasibility and fiber characterisation to pilots, site-specific training of the event library, and system integration with SCADA and security software.
- Fiber route and quality analysis (OTDR, loss budget)
- Pilot section selection and field tests
- Site-specific calibration of event classes
- SCADA, VMS and control room integration
| Criterion | DAS (fiber optic) | Cameras, radar and point sensors |
|---|---|---|
| Coverage | Typically tens of km continuous from one interrogator | A device and mast every few hundred metres |
| Field power | No power or electronics along the cable | Power and communications needed at every node |
| Buried and underground events | Detects digging, leak and drilling vibration | Cameras and radar cannot see below ground |
| Visibility | Buried and covert | Visible, can be targeted or bypassed |
| Weather and lighting | Not optically affected by fog, darkness or rain | Cameras degrade in fog and darkness |
| Use of existing assets | Can use spare fiber in the ROW | Requires new installation |
| Visual verification | No imagery, but cues cameras | Cameras provide visual confirmation |
Frequently asked questions
How precisely can DAS locate a pipeline leak?
DAS typically locates events along the fiber with a spatial resolution of a few metres. Actual performance depends on leak rate, line pressure, distance between fiber and pipe, and soil conditions. For small leaks, combining DAS with Distributed Temperature Sensing (DTS) improves detection reliability.
Can existing telecom fiber be used for DAS?
Usually, yes. A spare strand of standard single-mode fiber laid along a pipeline or power cable route is generally sufficient for DAS. Distance from the pipe, burial method and splice losses all affect performance, so fiber characterisation before commissioning is recommended.
How many kilometres can one DAS interrogator cover?
A single DAS interrogator typically covers tens of kilometres, with single-channel range often cited around 40-50 km. For longer pipelines, several interrogators are placed at stations along the route so that the entire line is covered without gaps.
What events can DAS perimeter security tell apart?
A DAS-based perimeter intrusion detection system (PIDS) can distinguish climbing, cutting and shaking on fences, walking, running and digging over buried cable, and vehicle movement. Classification relies on signal-processing and machine learning models trained on site-specific data.
How are false alarms reduced in DAS systems?
False alarms are reduced through high SNR, classifiers trained for the specific site, zone-based thresholds and event correlation. DuyuSense's patented DAS signal-processing method suppresses noise and improves SNR, helping separate harmless sources such as traffic, wind and rain from real threats.
Does DAS replace security cameras?
DAS complements cameras rather than replacing them. It detects and locates events along a long boundary, and a camera is then slewed to that point for visual confirmation. This reduces the number of feeds operators must watch continuously and lowers their workload.
Can buried power cables be monitored with DAS?
Yes. Using fibers laid with the cable or integrated into it, DAS detects excavation and third-party interference along the route. Adding DTS allows cable temperature monitoring as well, supporting loading and hot-spot analysis from the same fiber infrastructure.
What does DuyuSense offer for pipeline monitoring projects?
DuyuSense develops DAS and FBG monitoring systems and offers engineering support for feasibility, fiber analysis, pilots, site-specific training of event classification and system integration. For pilots and project partnerships, contact contact@duyusense.com.