Distributed Acoustic Sensing (DAS) turns an optical fiber into thousands of virtual acoustic and vibration sensors. It enables continuous monitoring over long distances and is increasingly used for pipelines, railways, power cables, perimeter security and other critical infrastructure.
DAS and DVS (Distributed Vibration Sensing) are sometimes used interchangeably in the industry. However, their actual capabilities can be very different.
For HERTZINNO, the distinction is simple:
DVS focuses on detecting and locating vibration. DAS adds advanced signal analysis and event intelligence.
A DAS interrogator sends laser pulses into a standard single-mode optical fiber and analyzes Rayleigh backscattered light.
When vibration, acoustic energy or mechanical disturbance affects the fiber, the returned optical signal changes. By analyzing these changes, the system can determine where an event occurs and how the signal changes over time.
This allows one optical fiber to monitor many kilometers of infrastructure without installing thousands of conventional point sensors.
Fiber → DAS Interrogator → Distributed Acoustic Data
Fiber cable → laser pulse → vibration source → backscattered signal → DAS interrogator
DVS is primarily designed for distributed vibration detection.
A typical DVS workflow is:
Detect → Locate → Alarm
This is suitable for applications where the main requirement is to identify whether vibration has occurred and determine its location.
However, real industrial environments contain many sources of vibration.
For example, a buried pipeline may experience signals caused by:
If every vibration directly generates an alarm, operators may receive too many nuisance or false alarms.
This is where advanced DAS becomes more valuable.
DVS
Fiber ➡️ Vibration Detection ➡️ Localization ➡️ Alarm
DAS
Fiber ➡️ DAS Interrogator ➡️ Analysis Server ➡️ Signal Analysis ➡️ Event Classification ➡️ Alarm Decision
HERTZINNO DAS can be combined with a dedicated Analysis Server for advanced event processing.
Instead of immediately converting every detected vibration into an alarm, the system analyzes the signal first.
The workflow becomes:
Detect → Locate → Analyze → Classify → Decide → Alarm
The Analysis Server can evaluate multiple signal characteristics, including:
Time-domain features — how the signal changes over time.
Frequency-domain features — which frequency components are present.
Time-frequency characteristics — how frequency changes during an event.
Spatial characteristics — whether an event is stationary or moving along the fiber.
By combining these features, the system can distinguish different types of activities and determine whether they represent a real threat.
Show several events such as:
Excavation → High Risk
Vehicle → Recognized / Filtered
Walking → Low Risk
Mechanical Vibration → Recognized
Abnormal Event → Alarm
For many DAS applications, detecting vibration is relatively easy.
The more difficult challenge is determining:
Is this vibration actually important?
A highly sensitive system without event classification may generate large numbers of unnecessary alarms.
For example, in pipeline monitoring, a passing truck and an excavator operating directly above the pipeline may both create strong vibration.
Their risk levels, however, are completely different.
With intelligent event analysis, the system can evaluate the signal before generating an alarm.
This helps reduce unnecessary alarms and allows operators to focus on events that require action.
| Capability | HERTZINNO DVS | HERTZINNO DAS |
|---|---|---|
| Distributed vibration detection | Yes | Yes |
| Event localization | Yes | Yes |
| Basic alarm | Yes | Yes |
| Advanced signal analysis | Limited | Yes |
| Analysis Server | Not required | Supported |
| Time-frequency analysis | Limited | Yes |
| Event classification | Limited | Yes |
| Intelligent alarm filtering | Basic | Advanced |
| Complex event recognition | Limited | Yes |
In simple terms:
DVS tells you where something happened.
DAS helps determine where it happened, what happened, and whether it matters.
Advanced DAS is particularly suitable for applications where long-distance monitoring and event classification are both important.
DAS can detect excavation, heavy machinery, vehicles and other third-party activities along a pipeline route.
Event classification helps distinguish real threats from normal environmental activity.
DAS can monitor long fences, borders and critical infrastructure using buried or fence-mounted optical fiber.
A fiber installed alongside railway infrastructure can detect train movement and abnormal trackside activity over long distances.
DAS can monitor underground or overhead cable routes and identify construction activity or external interference.
Suggested image: DAS application overview
Pipeline | Railway | Power Cable | Perimeter
Distributed fiber sensing provides a major advantage: one optical fiber can act as thousands of sensing points.
But detection alone is only the beginning.
HERTZINNO DAS combines distributed acoustic sensing with advanced signal processing and an Analysis Server to provide more meaningful information from every detected event.
The objective is not simply to generate more alarms.
It is to generate better alarms.
HERTZINNO DAS — From Distributed Sensing to Distributed Intelligence.
