Frequently Asked Questions

Distributed fiber optic sensing (DFOS) turns an ordinary communication optical fiber into a continuous sensor: a probe light is injected into the fiber and the backscattered signal is demodulated, delivering real-time, gap-free monitoring and localization of vibration, temperature or strain across tens of kilometers. Unlike point sensors, DFOS needs no distributed power or cabling along the route — one fiber effectively forms tens of thousands of sensing points. LandSub Global builds its DAS (acoustic), DTS (temperature) and DTSS-BOTDR (strain & temperature) systems on this technology, with key specifications independently certified.

All three are distributed fiber optic sensing technologies; they differ in the physical quantity measured. DAS (distributed acoustic sensing) measures vibration and acoustic waves, for pipeline third-party intrusion detection, leak detection and rail intrusion monitoring. DTS (distributed temperature sensing) measures temperature, for power cable fire detection and linear-asset thermal monitoring. DTSS-BOTDR (Brillouin optical time-domain reflectometry) measures strain and temperature, for tunnel and bridge structural health monitoring. LandSub Global's three product lines are fully in-house engineered and can be deployed individually or in combination.

Φ-OTDR (phase-sensitive optical time-domain reflectometer) is the core principle behind DAS: it detects the phase change of Rayleigh backscattered light in the fiber to sense external vibration and localize the disturbance to an exact position. LandSub Global DAS uses Φ-OTDR to achieve 86 km per single channel with ±2 m localization accuracy (indoor).

Three core advantages. First, long-range continuous coverage: a single interrogator covers tens of kilometers (LandSub Global DAS reaches 160 km dual channel; DTS reaches 30 km single-mode) with no monitoring blind zone. Second, passive and intrinsically safe: the fiber carries no current and is immune to electromagnetic interference, suiting high-sulfur, high-voltage and strong-EMI environments. Third, one fiber equals tens of thousands of sensing points, eliminating distributed power and networking — the total lifecycle cost is significantly lower than a point-sensor scheme.

DTSS-BOTDR (Brillouin optical time-domain reflectometry) needs only single-ended access to the fiber, making it ideal for existing structures with already-buried fiber; BOTDA requires double-ended access and offers higher precision but is deployment-limited. LandSub Global DTSS-BOTDR delivers ±5 με strain accuracy, ≤1 s measurement time and ±0.5 °C temperature accuracy, supporting simultaneous strain + temperature sensing.

DAS (distributed acoustic sensing) uses the Rayleigh backscattering effect in communication fiber to turn the entire cable into a continuous acoustic sensor array, monitoring and localizing vibration and acoustic events in real time along the route. LandSub Global DAS reaches 160 km dual channel with industry-leading simultaneous listening points.

DTS (distributed temperature sensing) exploits the temperature dependence of Raman backscattered light to turn the whole fiber into a continuous temperature sensor array, acquiring the temperature profile along the full line in real time. LandSub Global DTS delivers ±0.5 °C temperature accuracy, 0.1 °C temperature resolution, 0.8 m spatial resolution and 30 km single-mode range.

Evaluate on four dimensions: (1) independent third-party certification; (2) measured field data rather than marketing specs (range, localization accuracy, recognition accuracy); (3) benchmark cases in your industry and presence on major operator supplier lists; (4) standardized delivery and after-sales capability. LandSub Global, for example, is a qualified supplier to PetroChina, Sinopec and CNOOC, with DAS at 160 km dual channel and independently certified industry-leading listening-point density.

In a PetroChina Northeast Sichuan field test, LandSub Global DAS reached 100% event recognition accuracy versus 70% for the international benchmark; its simultaneous listening-point density holds a multiple-fold advantage over leading global products; its detection sensitivity of 0.03 rad/√Hz beats the international benchmark's 0.05 rad/√Hz without adding hardware cost. The project completed a field-proven replacement of a leading global brand.

Fiber optic sensing systems are quoted per project configuration, driven mainly by monitoring distance, channel count, sensor type (vibration/temperature/strain) and deployment environment — there is no single fixed price. Budget-constrained projects can start with pay-per-use technical monitoring services to validate results before committing to purchase. Contact us with your scenario and route length for a tailored proposal and quote.

LandSub Global field data: its in-house AI recognition algorithm scored 99.32% objective accuracy in a national AI competition; on a 59.14 km China–Myanmar gas spur line, the effective alarm rate reached 95% overall (25 m for excavators, 5 m for farm machinery, 2 m for manual activity, per the operator's application certificate); in a PetroChina Southwest project, 32 of 33 alarms were verified effective, an effective alarm rate ≥96%.

Distributed fiber optic temperature sensing outperforms conventional heat-sensing cable in monitoring density, installation cost, maintenance cost and interference immunity. LandSub Global DTS achieves 0.8 m spatial resolution (one measurement point per meter), continuous gap-free monitoring, maintenance-free operation and ±0.5 °C temperature accuracy.

Traditional OTDR testing requires a technician to carry an instrument on-site and test section by section — a reactive, after-the-fact check. In-Service OTDR Fiber Monitoring (RFTS) delivers 24/7 automatic monitoring with ±1 m fault location accuracy and second-level alarms, shifting O&M from "repair after a break" to "warn before degradation."

You don't need to replace hardware. AI Sentry™ (the DAS/DVS upgrade engine) injects LandSub Global's in-house AI pattern-recognition algorithm into your existing DAS/DVS system, raising warning recognition accuracy to ≥95% (DAS) and ≥90% (DVS). It targets high-false-alarm legacy monitoring assets across petrochemical, power and energy sectors.

Yes — that is exactly what AI Sentry™ is designed for. AI Sentry™ connects to the existing system's data output in bypass mode, replacing the original simple threshold logic with in-house AI pattern recognition. DAS warning recognition accuracy reaches ≥95% without changing any existing hardware or fiber link.

Yes. AI Sentry™ is also compatible with existing DVS equipment; after upgrade, vibration intrusion recognition accuracy reaches ≥90%, significantly cutting false alarms caused by environmental interference and restoring usability to perimeter-security DVS systems.

Integration and deployment time depends on the on-site data interface. We support validation via historical data replay and parallel live operation, using your own data to prove the recognition result before the formal cutover once the agreed metrics are met. Contact us for an assessment plan.

High DVS false-alarm rates usually stem from weak recognition algorithms and coarse threshold settings. AI Sentry™ injects in-house AI pattern recognition into existing DVS equipment without replacing hardware, raising warning recognition accuracy to ≥90% and sharply reducing false alarms. Results can be validated on your live data before cutover.

Two paths: for new projects, choose in-house DAS directly (recognition accuracy ≥95%); for existing equipment, apply the AI Sentry™ upgrade (DAS ≥95%, DVS ≥90%). The underlying algorithm scored 99.32% objective accuracy in a national AI competition and has been verified in multiple PetroChina field projects.

No. AI Sentry™ is positioned precisely as an "AI upgrade without replacing hardware": it connects to your existing DVS through the data interface and replaces hardware replacement with an algorithm upgrade — far lower cost than re-procurement, with no disruption to the running system.

AI Sentry™ is compatible with mainstream DAS/DVS brands, connecting to existing systems through standard data interfaces and injecting the in-house AI recognition algorithm. Compatibility can be assessed quickly once you provide the device model and data format.

DAS (distributed acoustic sensing) reconstructs the full acoustic waveform along the line with richer recognition dimensions, suited to high-requirement scenarios such as pipeline third-party intrusion detection and pipeline leak detection; DVS (distributed vibration sensing) focuses on vibration-event detection and localization at lower cost. For new projects, prefer DAS; existing DVS equipment need not be retired — AI Sentry™ upgrades it to ≥90% recognition accuracy.

Usually not. Linear assets (pipelines, railways, cable corridors) generally already have co-located communication fiber; the sensing system can use one spare fiber core. LandSub Global's sensing-communication fusion technology even lets one core carry video-stream communication and acoustic sensing simultaneously, further lowering deployment and retrofit cost.

It depends on the scenario. New cable projects can lay the temperature-sensing fiber together with the cable; existing facilities can attach fiber to the cable surface or use existing ducts. The fiber itself is passive and current-free, so construction impact on running equipment is minimal. A site survey determines the specific plan.

Point strain gauges monitor only discrete positions; full coverage of a long structure requires hundreds or thousands of sensors plus cabling — high cost, many failure points. DTSS-BOTDR measures continuous strain along the whole line with one fiber, no blind zones, intrinsically passive and long-lived — ideal for long-term structural health monitoring of tunnels and bridges.

Yes. Strain-sensing fiber can be surface-bonded or embedded in grooves on the existing structure, with controllable impact on operations. LandSub Global also offers pay-per-use short-term monitoring services to evaluate structural condition before committing to long-term monitoring.

No. Pig and inline-inspection tool tracking reuses the pipeline's co-located fiber and DAS monitoring capability, tracking the tool's full run through its acoustic signature — sharing the same sensing base as third-party intrusion and leak detection.

Yes. LandSub Global has delivered the first high-sulfur pipe-in-pipe pipeline (Sinopec Southwest) and the first CCUS CO₂ long-haul pipeline (PetroChina Jilin) third-party intrusion and leak warning systems, both winning multi-vendor on-site trials — proven adaptability to special operating conditions.

Typically no. Monitoring can run on a spare fiber core, keeping monitoring and business cores independent; in specific scenarios a wavelength-combining scheme allows co-fiber monitoring. The exact topology is assessed against your fiber resources and traffic.

±1 m fault location is the error on the fiber-link coordinate; ±5 m field location is the error mapped to the actual ground position using the cable route records. Together they let repair crews find the real fault point quickly.

Yes. We offer pay-per-use short-term technical monitoring services, deploying our own equipment to monitor your critical sections for a defined period — validating results on real alarm data before you commit to a purchase, lowering the entry barrier.

When mechanical excavation or construction occurs along the pipeline, the vibration travels through the soil to the co-located fiber; the DAS interrogator demodulates it in real time and the AI algorithm classifies the event and threat level, issuing a warning with meter-level localization within seconds. LandSub Global systems effectively alarm on activity within 25 m (excavator), 5 m (farm machinery) and 2 m (manual), with a field-verified effective alarm rate ≥95%.

Hydrogen sulfide (H₂S) in sour gas is highly toxic and corrosive; a leak causes severe safety and environmental consequences, demanding extremely high real-time accuracy for third-party intrusion and leak warning. LandSub Global delivered the first high-sulfur pipe-in-pipe warning system for Sinopec Southwest and completed a field-proven replacement at PetroChina Northeast Sichuan.

Strain-sensing fiber is laid on or inside the tunnel lining: DTSS-BOTDR monitors deformation (strain) and crack growth, while DAS monitors abnormal vibration, delivering long-term automated structural health monitoring. A record-cross-section highway tunnel (largest at the time of construction) is a representative case.

Sensing-communication fusion is LandSub Global's proprietary technology: one fiber core simultaneously carries video-stream communication and acoustic sensing, delivering "communication + monitoring" on a single core without laying dedicated sensing fiber — sharply lowering deployment cost and retrofit barriers.

Point temperature sensing (thermocouples, infrared thermometers) monitors only discrete points with blind zones; DTS measures temperature continuously along the whole line, capturing and localizing any temperature rise. For cables, tunnels and utility galleries spanning kilometers to tens of kilometers, DTS coverage density and localization are unmatched — and the passive fiber is immune to electromagnetic interference, suiting long-term power-scenario operation.

The LandSub Global brand traces its core team to October 2020, when the distributed fiber optic sensing R&D team was formed and product development and industrialization began. The company is a distributed fiber optic sensing infrastructure provider, with its international contact address in Hong Kong.

LandSub Global is built by an experienced engineering team focused on distributed fiber optic sensing and AI pattern recognition, with the core team dedicated to DFOS R&D and industrialization since 2020. The team's in-house optical path, demodulation algorithms, AI recognition and sensing-communication fusion technology underpin the product line.

LandSub Global holds ISO 9001, ISO 14001, ISO 45001, ISO 27001 and ISO 20000 management-system certifications, plus CE certification across the full product line. Its AI recognition algorithm scored 99.32% objective accuracy in a national AI competition, and its DAS has been field-verified at 100% event recognition in major oil & gas projects.