DAS
Distributed acoustic sensing
Registration and localization of vibroacoustic events along a fiber-optic line.
Explore DAS ↗Fiber-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.
Technology and expertise
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 microphones ↗FPGA
FPGA development
High-speed interfaces, DMA, memory, and streaming digital signal processing.
Explore FPGA capabilities ↗
SHM
Structural health monitoring
Field sensors, data acquisition, server-side processing, and continuous asset observation.
Explore the SHM project ↗Distributed sensing
DAS and DTS: one optical line, two classes of measurement
A measurement unit interrogates sensing fiber installed along an asset. DAS registers vibroacoustic events; DTS builds a distributed temperature profile.
Distributed acoustic sensing
Registers signals along an optical line and associates an event with a location. A4 project materials cover long routes, perimeters, and industrial assets.
Distributed temperature sensing
Measures a temperature profile along the sensing cable. Project materials include heat-exchange equipment, cryogenic processes, and long linear assets.
Signal path
From a physical event to data in the customer 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.
- 01
Physical event
Temperature, vibration, sound, or strain changes the parameters of the sensing fiber.
- 02
Optical response
The fiber acts as a distributed sensor or connects a sequence of discrete sensing elements.
- 03
Measurement unit
Optical and electronic subsystems interrogate the line and produce a digital measurement stream.
- 04
Signal processing
Streaming algorithms, digital filtering, and FPGA processing isolate the measured event.
- 05
Software and integration
The result is displayed in a web interface or delivered to an external software environment.
Optical microphones
Discrete acoustic elements on a shared fiber-optic 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
The available materials show a working prototype, a three-microphone experiment, and results from 2025 field trials.
FPGA development
From the digital signal path to a complete measurement system
We design the digital layer of measurement systems around the required data rate, latency, volume, and operating conditions. We can develop a single subsystem or take responsibility for the complete signal path, from FPGA and ADC to application software.
End-to-end engineering for the task
We work with high-speed multichannel I/O, PCIe/XDMA, JESD204, Ethernet/TCP, drivers, and protocols. Our scope includes stream synchronization, I/Q and spectral processing, recording, storage, and data visualization.
We combine architecture, FPGA firmware, DSP, and software into a complete solution designed around the requirements of a particular instrument.
Structural health monitoring
SHM: from a field sensor to the control-room system
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 project materials cover distributed measurements, infrastructure monitoring, and experimental acoustic systems.
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