FAQ RaySense Fiber Optic Sensor Cable

Frequently Asked Questions About the RaySense Distributed Acoustic Sensor (DAS)

Demonstration Video of the RaySense system and its Capabilities

What is Distributed Acoustic Sensing (DAS)?

Distributed Acoustic Sensing (DAS) is a groundbreaking technology that transforms standard optical fibers into an extensive array of highly sensitive acoustic sensors. By leveraging existing fiber-optic cables, DAS provides continuous, real-time acoustic data over extensive distances, offering unmatched precision and reliability. This article delves into the intricate workings of DAS, its diverse applications, and its numerous advantages, illustrating why it stands at the forefront of modern sensing technologies.

How Distributed Acoustic Sensing (DAS) Works

  1. Utilizing Optical Fiber: At the heart of DAS technology are standard telecommunication optical fibers, which are already widely deployed and easy to install in various environments. These fibers are typically used for data transmission but can be repurposed for acoustic sensing without any modifications.
  2. Laser Pulse Technology: A laser pulse, generated by a DAS interrogator unit, is transmitted through the optical fiber. As the pulse propagates along the fiber, it interacts with the minute imperfections and variations in the fiber’s glass structure.
  3. Backscatter Phenomenon: These interactions cause a small portion of the light to be scattered back toward the interrogator unit in a process known as Rayleigh scattering. The pattern of this backscattered light holds critical information about the vibrations and acoustic signals along the fiber.
  4. Advanced Signal Processing: The DAS interrogator unit analyzes the backscattered light to detect changes induced by acoustic vibrations. By precisely measuring the time it takes for the backscattered light to return, the system can accurately determine the location and nature of these changes along the fiber.
  5. Acoustic Data Generation: The variations in the backscattered light correspond to the acoustic signals that interact with the fiber. Advanced algorithms process this data to produce detailed information about the acoustic environment, enabling the detection of specific events and conditions.

Applications of Distributed Acoustic Sensing (DAS)

  1. Seismic Monitoring: DAS technology is instrumental in the oil and gas industry for conducting seismic surveys. It enables the detection and mapping of underground resources and provides continuous monitoring of the integrity of wells and pipelines. This capability is crucial for preventing leaks and other potential hazards.
  2. Infrastructure Monitoring: DAS is widely used to monitor the condition of critical infrastructure such as pipelines, railways, and bridges. By detecting vibrations and movements, DAS can identify potential issues like leaks, structural weaknesses, and unauthorized activities, enabling timely maintenance and intervention.
  3. Security and Surveillance: DAS offers an effective solution for perimeter security in sensitive areas, including borders, military installations, and critical facilities. The technology can detect and pinpoint intrusions by sensing footsteps, vehicle movements, and other disturbances, providing a robust security layer.
  4. Environmental Monitoring: DAS plays a significant role in environmental studies by monitoring natural phenomena such as earthquakes, landslides, and subsurface activities in real time. This real-time data is invaluable for early warning systems and disaster response strategies.
  5. Traffic Monitoring: DAS systems are deployed alongside roadways to monitor traffic flow, vehicle speeds, and the types of vehicles passing by, based on their acoustic signatures. This application aids in traffic management, congestion reduction, and the planning of transportation infrastructure.

Applications of Distributed Acoustic Sensing (DAS)

  1. Seismic Monitoring: DAS technology is instrumental in the oil and gas industry for conducting seismic surveys. It enables the detection and mapping of underground resources and provides continuous monitoring of the integrity of wells and pipelines. This capability is crucial for preventing leaks and other potential hazards.
  2. Infrastructure Monitoring: DAS is widely used to monitor the condition of critical infrastructure such as pipelines, railways, and bridges. By detecting vibrations and movements, DAS can identify potential issues like leaks, structural weaknesses, and unauthorized activities, enabling timely maintenance and intervention.
  3. Security and Surveillance: DAS offers an effective solution for perimeter security in sensitive areas, including borders, military installations, and critical facilities. The technology can detect and pinpoint intrusions by sensing footsteps, vehicle movements, and other disturbances, providing a robust security layer.
  4. Environmental Monitoring: DAS plays a significant role in environmental studies by monitoring natural phenomena such as earthquakes, landslides, and subsurface activities in real time. This real-time data is invaluable for early warning systems and disaster response strategies.
  5. Traffic Monitoring: DAS systems are deployed alongside roadways to monitor traffic flow, vehicle speeds, and the types of vehicles passing by, based on their acoustic signatures. This application aids in traffic management, congestion reduction, and the planning of transportation infrastructure.

What parts does a fiber optic system includes?

The RaySense fiber optic security system usually includes sensor cable in the length of choice, End line unit and laser unit/Server (APU). Other accessories are optional and needed to be added separately.

How long of a fence or ground can the RaySense system monitor?

The Maximum length is 100km/62mile but the RaySense family of products is sold in 1 or 2 channels and each channel can monitor 5km/3.1 miles to 100km/62mi.
In order to cover a longer perimeter, multiple systems (APUs) can be combined to cover the whole perimeter line.

If the sensor cable gets cut or broken what happens?

If the fiber optic sensor cable gets cut, an alarm will trigger in the exact location of the cut or fault. The RaySense DAS system would detect up to the cut location as well. If installed in a 2-channel redundant cut-resistant configuration, no loss of signal or detection will happen with a single cut.

How accurate is the RaySense detection?

Detection performance and detection accuracy are ±3 m (10 ft) on standard chain link fences. Two disturbances must be separated by a minimum of 20 meters (65 feet) to be reported separately because vibrations on the fence can travel sideways and affect a larger area of the cable.

Can the sensitivity of the sensor be adjusted?

Sure! The RaySense artificial intelligence (AI) is doing most of the work! But in case fine tuning is needed, there are options to set up software assignable and adjustable zones. Each zone can have its own sensitivity and detection characters.

Does the system need any calibration before I can use it?

The RaySense is a highly sophisticated system that can detect and analyze very long cables. A certified technician would have to perform a calibration process to adjust the system performance to each site.

Does wind or rain can cause false alarms?

The way the RaySense system works: Distributed Acoustic Sensing (DAS) sensors “listen” to the cable acoustics and are able to determine by comparing the signal to a large database of signatures as of what the acoustic signature looks like such as cut, climb, digging, vehicle and more.

Vibrations caused by wind, rain and small animals are usually not be picked up by the system as they don’t match the database of acoustic signatures we would like to detect.

Can the RaySense work on any fiber optic cable?

The RaySense system operates by monitoring a standard single-mode fiber optic cable. Although it is theoretically possible to monitor any fiber optic cable, for security purposes, it is highly recommended to use the RBtec special cable, which is specifically designed for outdoor, direct burial, and security applications. However, in situations where the customer already possesses a fiber optic cable and no other alternative is available, it is still possible to use it.

If the cable got cut can it repaired?

Yes! Like any fiber optic cable the RaySense cable can be repaired by a fusion splicing.

Have any other questions? please contact us at Info@rbtec.com

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