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Standoff Chemical Agent Detector

CATSI™ – Compact Atmospheric Sounding Interferometer

Chemical Warfare Agents (CWAs) and Toxic Industrial Compounds (TIC) standoff detection of the presence of threats in the air of any toxic gas over a range of more than 5 km.

The Compact Atmospheric Sounding Interferometer (CATSI™) is a fast scanning interferometer covering the spectral range from 3 μm to 18 μm (560 cm−1 to 3300 cm−1) providing state-of-the-art radiometric accuracy for thermal emission measurements.

The differential technology (real time scene background radiation optical subtraction) offers better sensitivity and spectral purity than most other IR spectroscopic techniques. The spectroradiometer is based on the ABB MR Series of Fourier Transform interferometer.

The CATSI – CWAs Standoff Detector system offers an outstanding performance and is easy to use. The graphical user interface of the software provides clear and simple commands and real-time spectral feedback.


  • Real-time detection of CWA and several TICs
  • Detect and identifies in up to 5 km distances
  • Day & Night operation
  • Optimal sensitivity through adaptive processing of the background environment
  • Automated self-calibration sequence
  • Intuitive user-friendly interface


  • Standoff detection saves lives
  • Invaluable tactical and strategic information
  • Unattended operation
  • Highest sensitivity on the market
  • Longest reliable detection range
  • Low false alarm rate
  • Benchmarked against COTS systems (IPT 2008)

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Models & Specs

CBRNE Contamination Avoidance

The armed forces ability to detect and identify CBRNE hazards (Chemical, Biological, Radiological, Nuclear and Explosive warfare (including terrorism) hazards) is becoming the center stage of the army transformation. A key element is the availability of reliable and effective chemical threats standoff detection solutions offering the troops with advanced early-warning capabilities for contamination avoidance.

CATSI (Compact Atmospheric Sounding Interferometer) is a militarized sensor developed by Defence Research & Development Canada (DRDC) under the Canadian Forces Chemical Agent Sensor project. The design of CATSI meets the needs of the CF for the standoff detection of Chemical Warfare Agents (CWA) and Toxic Industrial Compounds (TIC).

Using sophisticated recognition pattern algorithms, this innovative system integrates a proven Fourier-Transform Spectroscopy (FTS) sensing technique that can automatically scan the surrounding atmosphere to detect, classify, identify and report the presence of chemical agents in gaseous form while discriminating against both natural and manmade surrounding interferents.

The CATSI chemical agent sensor is produced under license with the permission of Defence R&D Canada, an Agency of the Canadian Department of National Defence. See “A militarized sensor for passive standoff detection of CWA

Troops protection

CATSI – a fully militarized standoff chemical agent detector – offers advanced warning of chemical threats to protect troops and strategic facilities to keep control of the battle field

Easy to deploy and to use, CATSI provides reliable geolocalized chemical threats alerts. This information truly simplifies field operations and deployment scenarios by providing a decisive tactical advantage. This innovative product assists commanders in taking timely decisions with high confidence level.


  • Designed for use with CBRNE attire
  • Operation in the most demanding environments
  • Benchmarked against COTS systems (IPT 2008)
  • Technology validated by Canadian Defence and currently deployed within DND

Tactical and strategic information

  • Chemical warfare agents identification
  • Simplifies field operations and deployment scenarios by providing a decisive tactical advantage
  • Assists commanders in taking timely decisions with high confidence level
  • Seamless integration with defense information networks
  • Keep troops at a safe distance from chemical threats
  • Increase reaction time

Reliable results

  • Longest reliable detection range
  • Highest sensitivity on the market
  • Low false positive and false negative alarm rates
  • Field proved instrument design
  • MIL-STD compliant

CATSI project history

The CATSI project originated in 1995 from DRDC-Valcartier as a DND (Department of National Defence) effort to develop the technology of a highly sensitive field-rated instrument for the remote detection of chemical vapors. Relying on ABB expertise for the development and delivery of CATSI, DRDC-Valcartier has been provided with the first generation of field-deployable Fourier-Transform Infrared (FTIR) spectroradiometer capable of differential detection (real time scene background radiation optical subtraction).

In 2005, DND initiated a project with the requirement to bring the CATSI technology to manufacturing maturity and included the delivery of Engineering Demonstrator Model (EDM) units. Under the lead of DRDC- Valcartier, the CATSI-EDM demonstrator units were built on the extension of experience learned from the original CATSI prototype, and the performance expected from today’s technologies. The CATSI-EDM project was completed in 2009 with the delivery of the demonstrator units. CATSI is the result of more than 10 years of extensive research leaded by DRDC-Valcartier on the passive standoff detection of chemical vapors.

CATSI Historical Perspective: 20 years of development


CATSI-EDM: Recent advances in the development and validation of a ruggedized passive standoff CWA sensor”, H. Lavoie et al. [SPIE proceedings 2008}]

“CATSI EDM – A New Sensor for the Real-Time Passive Stand-off Detection and Identification of Chemicals” J.M.Thériault et al. 2010 []

 “CATSI EDM – A militarized sensor for passive standoff detection of CWA”
J.-M.Thériault et al. 2010 []

CBRNe World, Autumn 2010, "CAT on a hot TICs roof", J.-M. Thériault

Differential Detection Operating Mode

Real time scene background radiation removal by optical subtraction

The performance of current deployed technologies used for passive standoff detection is impacted by the large clutter of infrared emissions generated by the interfering atmosphere, the background of a targeted scene and the self-emissions of the instrument.

CATSI is a fast scanning dual Field-of-View (FOV) spectral infrared system based on a concept developed by DRDC-Valcartier and designed to mitigate the clutter impact of external infrared emissions. Its advanced sensing technique utilizes a 4-ports FTIR interferometer design (2 inputs/ 2 outputs) allowing the target signature being detected in real-time and void of significant background clutter. It draws the advantages of differential detection mode which subtracts in real-time the background of the scene from the target signal, resulting in the suppression of the background component and sensor self-emission.

Gas detection by differential measurement

System description

CATSI features a modular architecture and consists of an optical sensor head mounted on a remotely operated pan & tilt tripod. The sensor can be operated from a local operator console which can operate by itself or via a remote operator console. The instrument power is supplied from an auxiliary power source (batteries) or electrical harnesses and power converter.

The main function of the optical sensor head is to capture the infrared radiation emitted from the scene, resolve the spectral contents of the captured radiation by means of a Michelson interferometer and then transmitting the spectral radiance signal to the control computer for real-time signal processing to chemical agent   detection information. The sensor optical head includes a view finder device (color CCD sensor), a input telescope coupled to a FTIR interferometer modulator, a digital compass and integrated black body used for self-calibration of the system.

The CATSI local operator console integrates the control and processing electronics used to remotely operate the optical sensor head with the pan & tilt scanner, and spectral analysis. The local operator console is equipped with a viewer display (night and goggles compatible), an audio and visual alarm system and also includes all the required operator’s controls used to enter GPS coordinates, modify the behavior or setting parameters of the scene scanning pattern, initiate self-test and calibrated the system.

The remote operator console consists of a rugged portable computer integrating the sophisticated software functions. It is used to configure the advanced settings of the optical sensor head such as sensitivity or resolution, scanning pattern behavior, system self-tests, etc. The remote operator console can interface to a network of up to six optical sensor heads operating simultaneously.

  • Dual Input Ports for optical subtraction
    • The resulting output signal is a subtraction of the two inputs in real time, requiring no processing
    • Optimal for faint targets identification

Performance demonstration

  • Users trial, BFC Valcartier, Sep 2007
  • Invitational trial ADIS IPT, Sep 2008
  • Lab test on real agents DRDC Suffield, Nov 2008
  • Passive ranging by triangulation, June 2009

Performance trial

Area detection and Identification System (ADIS) Invitational Performance Trial (IPT).
Conducted under realistic field conditions at 3.7 and 5 km from the cloud release point.

Rigorous Test Rules:

  • Gases: Unknown SF6 or F134 or No Gas
  • Release: Unknown time in a 5 minutes window
  • Cloud Size:
    • > 37 m @ 3.7 km ;
    • > 50 m @ 5 km

CATSI EDM successfully completed testing exceeding a probability of D&I of 80% with a 95% confidence requirement.

Standoff chemical agent detection

Because of its versatility, infrared spectroradiometry is used in several measurement applications defense and security applications. The ability to interrogate light that has interacted with a target by means of reflection, absorption or even indirectly allows acquiring important insight remotely. The electromagnetic radiation carries useful chemical and temperature information, answering important questions such as what is the chemical composition of the target and what is its temperature.

Infrared radiometry remote sensing: detection, identification and quantification of targets.

The ABB CATSI is able to sense the presence of chemical agents from a safe distance and in a completely covert manner, since it is a passive instrument. CATSI detects the infrared that is emitted or absorbed by the chemical species surrounding us. Chemical molecules leave a distinct signature, akin to a fingerprint, allowing the sensor to identify the species viewed in the line of sight. By scanning the surrounding space, CATSI is able to mount guard day and night autonomously and protect our troops and assets.

  • Troops and sites protection
  • Surveillance
  • Reconnaissance
  • Covert operations

Providing safety in a dangerous world

CBRNE – Chemical, Biological, Radiological, Nuclear and Explosive warfare (including terrorism) hazards

Our soldiers face many challenges. We owe it to them to protect their lives with all means available. Reducing the threat of chemical attacks has been a longstanding quest for defense forces throughout the world. Today, by using the ABB standoff chemical detectors, our forces can benefit from effective protection against chemical attacks.

ABB offers the CATSI, a unique solution for standoff chemical agent detection. This militarized sensor automatically scans the surrounding area to detect, identify and report the presence of chemical agents while discriminating against natural and manmade substances. With its library of more than 100 warfare chemical agents and dangerous toxic industrial chemicals (TICs), CATSI is the perfect tool to quickly assess and avoid these types of threats in the field and around critical assets.

CATSI – Compact ATmospheric Sounding Interferometer

Available in line-of-sight and imaging models:

  • CATSI Mk4
  • iCATSI


CATSI Mk IV is a militarized sensor designed to meet the needs of the Canadian Forces for standoff detection of Chemical Warfare Agents (CWA) and Toxic Industrial Compounds (TIC).

Using sophisticated recognition pattern algorithms, this innovative system integrates a proven Fourier-Transform Spectroscopy (FTS) sensing technique that can automatically scan the surrounding atmosphere to detect, classify, identify, and report the presence of chemical agents in gaseous form while discriminating against both natural and manmade surrounding interferents.

See data sheet for system description and list of specifications.

High Detection and Identification Capabilities at Long Distances

CATSI Mk IV is the production evolution of the field-tested CATSI Engineering Demonstrator Model (EDM) and the CASSIDI chemical remote sensing algorithms. It has the capability to efficiently detect low concentrations of CWA and TIC at distances up to 5 km. The CATSI Mk IV offers unmatched sensitivity in order to provide high-quality detection and identification results. Its optical input and collection field of view are optimized for long distance measurement

Networked Detection for Efficient and Versatile Protection

Up to six CATSI Mk IV detector units can be controlled by a single remote operator interface. This allows the protection of a large perimeter even in complex terrains or urban settings. Also, a network of CATSI Mk IV can determine the range of chemical threats and plot it on a map on the remote operator interface to simplify decision making in the presence of threats.

CATSI Mk IV for standoff gas detection

  • Ruggedized and fully militarized sensor to meet CF global operations, offering advanced warning of chemical threats to protect troops and strategic facilities
  • Based on real-time optical subtraction allowing suppression of background radiation & instrument self-emission (technology validated by Canadian Defence)
  • Innovative capability development  with emphasis on:
    • Highly sensitive field-rated sensor (input optics):
    • Long range remote sensing: Detect and identifies in up to 5 km distances:
    • Very Wide Area surveillance (Scanning of entire battlefield):
  • Automatically scans the surrounding area to detect, identify, and report the presence of suspect agents while discriminating against natural and manmade interferents
  • Library containing more than 100 dangerous threats (encrypted and updatable library):
    • Chemical Warfare Agents (CWAs)
    • Toxic Industrial Compounds (TICs)
    • Non-Traditional Toxic Agents (NTAs)
  • Provide situation awareness to commander with alarms, and provide ATP 45 NBC4 (Allied Technical Publication 45 Nuclear Biological and Chemical 4) report generation for seamless integration with other defence information systems


  • Enhanced sensitivity using background suppression
  • Easy to deploy and to use
  • Fully unattended system
  • Continuous 24h day and night operation
  • High resolution viewfinder display (boresight camera) for context visualization
  • Automated self-calibration and Initiated Build-In-Test (IBIT)
  • Provides reliable 3D geolocalized chemical threats alerts
  • User friendly software interface with intuitive results (audible and visible alarms)
  • A service life expectancy of 10 years
  • MIL-STD compliant


  • Unrestricted 360° azimuthal surveillance scanning with depression/elevation angles ranging from −10° to +40°
  • Operate with a local console or a remote console, which can be located at up to 70 m from the sensor
  • Networkable solution (of up to 6 units for large coverage)
  • Provisions for wireless communications
  • Using AC/DC, DC/DC power sources and auxiliary batteries
  • Operation temperature: −32 to 49°C

CONOPS and Challenge: Wide Area Chemical Monitoring

Innovative elements



  • Multi-pixel imaging differential spectroradiometer for standoff detection and quantification of chemical threats
  • Small scanning detector array with a long cut-off
    • Linear array of 16 × 1 photodiodes
    • 10 mrad, single pixel field of view with measurement rate 10 iFOV/sec
    • Extended spectral range coverage: 7–14 μm
    • High sensitivity

Optimization of FOV and Fill Factor

  • Line detector scanning provides spatial information
    • Fewer pixels à high pixels throughput à high sensitivity
    • Cube rate > 3 cubes/s
    • LWIR spectral range cut off > 14 um

iCATSI operating principle

Summary of characteristics

Operational modes

 Direct mode:

Differential mode:



SF6 release (500 m of distance)

Gas releases field trials

  • iCATSI F134 gases detection:
  • Configured in optical subtraction
  • Line scanning MCT (24 x 16 pixels window)
  • F-134, 50 L in one minute
  • Real time display
  • Colormap proportional to probability of presence (black: none; red: high)


Telescope and camera modules

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