DAS
Distributed acoustic sensing
Registration and localization of vibroacoustic events along a fiber-optic line.
Explore DASFiber-optic sensing and signal processing for engineering systems
A4 Sensors develops instruments and software for distributed acoustic and temperature sensing, optical microphones, structural monitoring, and FPGA-based computing solutions.
Technologies and capabilities
Core capabilities
Two classes of distributed sensing, fiber-optic acoustics, high-speed digital processing, and structural monitoring.
DTS
Distributed temperature sensing
A temperature profile along sensing cable for industrial and linear assets.
Explore DTS
OPTICAL MIC
Optical microphones
Discrete fiber-acoustic elements, a shared interrogation line, and per-channel processing.
Explore optical microphonesFPGA
FPGA development
Multichannel acquisition, FPGA signal processing, high-speed interfaces, and application software.
Learn more about FPGA development
SHM
Structural health monitoring
Field sensors, data acquisition, server-side processing, and continuous asset observation.
Explore the SHM projectDistributed sensing
DAS and DTS: distributed acoustic and temperature sensing
A measurement unit interrogates the sensing fiber along an asset. Distributed acoustic sensing (DAS) registers vibroacoustic events, while distributed temperature sensing (DTS) produces a temperature profile along the line.
Distributed acoustic sensing
Registers signals along an optical line and associates an event with a location. Designed for long routes, perimeters, and industrial assets.
Distributed temperature sensing
Measures a temperature profile along the sensing cable. A4 Sensors has applied the technology to heat-exchange equipment and cryogenic processes.
Operating principle
Signal path through the measurement system
A physical event changes the optical response, passes through the measurement unit and processing algorithms, and the result is displayed in software or delivered to an external system.
Fiber-optic microphones
Fiber-optic microphones on a shared sensing line
A fiber-optic microphone converts sound pressure on a membrane into an optical signal change. A DAS unit interrogates the line, while software processes each sensing element separately.
- 01
Sensing element
In the documented design, fiber is wound around an acoustically sensitive membrane, while weakly reflecting Bragg gratings separate measurement sections.
- 02
Shared optical line
A sequence of microphones connects to one measurement unit without local electrical power at every sensing element.
- 03
Per-channel processing
The software layer extracts and processes the acoustic signal from each microphone on the line.
- 04
Experimental verification
A working prototype was developed, followed by a three-microphone experiment and field trials in 2025.
FPGA development
FPGA firmware, drivers, and application software
We develop high-speed data-acquisition and processing systems. The scope can include FPGA firmware, ADC integration, drivers, communication protocols, and application software.
Development scope
We acquire and synchronize data from multiple ADC channels, implement I/Q processing and spectral analysis, and configure transport over PCIe, JESD204, and Ethernet.
When required, we also develop drivers, communication protocols, data recording, server-side components, and the measurement-system user interface.
Structural health monitoring
Continuous structural health monitoring
The system continuously relates structural condition to operating conditions. Field-sensor data passes through a protected acquisition node, is stored on a server, and is available to specialists in a unified interface.
Configuration of one implemented project as of 20 February 2024
- 7
- accelerometer-inclinometers
- 24
- displacement sensors
- 22
- strain sensors
- 3
- temperature sensors
- 6
- thermometric strings
- 1
- weather station
- 01
Field layer
Sensors record dynamics, displacement, temperature, strain, and weather conditions directly on the structure.
- 02
Acquisition and processing
Measurement channels converge at a protected acquisition node, where data is normalized and transferred to the server.
- 03
Software and alerts
The server stores history, compares values with defined criteria, and presents current conditions and notifications to specialists.
Experience and projects
Real assets, measurement systems, and working prototypes
A4 Sensors develops distributed measurement systems, infrastructure monitoring, and experimental fiber-optic acoustics.
01
Structural monitoring of a transport bridge
Field sensors, server infrastructure, an archive, and an interface for monitoring acceleration, temperature, displacement, weather, and strain.
02
Temperature profile of heat-exchange equipment
The project included a method for placing sensing cable in twisted tubes and measuring temperature along its full length.
03
14 km slurry-pipeline monitoring trial
A fiber-optic line was used to register acoustic events and test simulated leak scenarios at multiple points along the route.
04
Fiber-optic microphone prototype
A sensing element was assembled and field-tested, producing phase maps and spectrograms of the acoustic signal.
05
DTS for cryogenic and industrial processes
The instrument was used at LNG facilities for distributed temperature monitoring under cryogenic conditions.
Software and integration
A software environment designed for the project
We develop both individual services and integration gateways, as well as complete software systems for measurement equipment. The architecture is selected for the workload, data model, and customer infrastructure: REST, gRPC, WebSocket and TCP, industrial Modbus TCP and IEC 60870-5-104, relational, S3-compatible and time-series storage, containerized and virtualized deployment, Prometheus, and Grafana. If an existing solution is not sufficient, we develop the software component required for the project.
DTS / web interface
Example measurement-system interface
- Network layer
- REST / gRPC / WebSocket
- Industrial integration
- Modbus TCP / IEC 104
- Operations
- Docker / Prometheus / Grafana
Contact A4 Sensors