Passive RF sensing

providing modular air defense systems with early warning capability

Modern air defense depends on detecting threats as early as possible, without revealing your own position. Passive RF sensors deliver that capability.

Operating silently, they detect and geolocate hostile emitters in real time, allowing air defenders to maintain EMCON, gain valuable decision time, and cue other sensors or weapon systems for precise targeting.

Passive RF technology augments traditional radar systems—which are effective but exposed—by adding persistent, rapidly deployable sensors that deliver full Electronic Support Measures (ESM) capability. Aligned with the ‘mix, mass, modularity’ principles of modern IAMD, these sensors enable defenses that are flexible, scalable, and reconfigurable.

CRFS sensor networks seamlessly integrate into layered defense architectures—from Forward Operating Bases to strategic infrastructure—delivering real-time RF intelligence. The TRL‑9 technology fills a critical gap in an integrated air defense ‘Find, Fix, Track, Target, Engage, Assess (F2T2EA)’ process.

c-UAS VSHORAD SHORAD MRAD bubble

c-UAS / VSHORAD / SHORAD / MRAD

  • Operate in a contested & congested

  • EMOE

  • Function in GNSS-denied environments

  • Customizable signal detectors

  • Non-library-based detection

  • Radar augmentation

  • Interoperable with C2 software

  • Proven TRL-9 in real-world deployments 

Air defense applications

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Radar augmentation

A passive RF sensor network complements radar by acting as an early warning system, detecting hostile airborne targets without alerting the enemy and cuing targeting radar.

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Detect the signal of interest, not the platform

Custom built signal detectors search for specific signals (including telemetry, video links, payload data transfer) rather than for specific platforms.

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Highly accurate 3D TDoA geolocation

Time Difference of Arrival accurately geolocates the position of RF emitters in three dimensions by analyzing the time difference between each sensor and using advanced algorithms.

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Operate in GNSS-denied environments

CRFS has several tools to continue spectrum monitoring and geolocation missions in GNSS-denied environments.

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Operating under EMCON

Passive RF sensors allow air defenders to operate under EMCON as they can listen without emitting, increasing survivability and helping to monitor blue force comms.

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Interoperability

Through open API architecture, you can use CRFS’ spectrum monitoring and geolocation capabilities in your C2 system.

 

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Expertise

A CRFS Guide to Airborne Target Identification

Passive RF detection for Integrated Air and Missile Defence Systems (IAMD)

Passive Geolocation with 3D TDoA Whitepaper

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Book a call with an air defense advisor

Let’s discuss your air defense requirement, 3D TDoA, operating in GNSS-denied environments, and operating under EMCON.

Related reading

Augmenting Radar Systems with 3D TDOA
Air defense
Augmenting Radar Systems with 3D TDOA
by CRFS Marketing
Radar is a tried and trusted method of monitoring aircraft activity in the surrounding area. It is also, in certain circumstances, a blaring beacon advertising its own location to ...
Adding a fused passive sensing layer to IAMD systems
Air defense
Adding a fused passive sensing layer to IAMD systems
by Jaimie Brzezinski
BLUF: A radar-centric F2T2EA architecture depends on emitting RF energy, creating electromagnetic signatures that can be detected and geolocated by an adversary for ...
Passive air defense: geolocating airborne targets using detector-based 3D TDoA
Air defense
Passive air defense: geolocating airborne targets using detector-based 3D TDoA
by CRFS Marketing
While radar is a widespread and versatile tool for detecting and locating in the battlespace, it has a critical Achilles heel. As active systems, radars have their own EMS ...

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