Fact-checked by Grok 2 weeks ago

Radar warning receiver

A radar warning receiver (RWR) is a passive support measures device deployed on platforms such as , ships, and vehicles to detect, identify, and analyze electromagnetic signals emitted by enemy radars, thereby providing operators with real-time alerts on threat location, type, and severity to facilitate evasion or countermeasures. Primarily functioning as an in environments, the RWR scans wide frequency bands—typically 0.5–18 GHz and sometimes up to 40 GHz—using superheterodyne or crystal video receivers to intercept radar pulses without emitting signals itself, ensuring stealthy operation. Key components of an RWR include multiple directional antennas (often four, spaced 90 degrees apart for 360-degree coverage), a /processor unit that de-interleaves overlapping signals and matches them against a preloaded emitter based on parameters like , repetition , and , and an integrated or audio for threat visualization. This processing enables prioritization of threats by lethality—distinguishing, for instance, between radars and fire-control systems for surface-to-air missiles—and supports with active defenses like jammers or dispensers. Developed from rudimentary detectors during , RWRs matured significantly during and immediately after the with systems like the AN/ALR-45, and continue to evolve in digital and AI/ML-enabled forms such as the AN/APR-39 family and Raytheon's cognitive systems (as of 2025), which offer enhanced for high-threat-density scenarios and improved accuracy in bearing estimation. These advancements have proven vital in modern aerial and naval operations, boosting platform survivability by enabling proactive maneuvers against radar-guided weapons.

Fundamentals

Definition and Purpose

A radar warning receiver (RWR) is a passive electronic support measure (ESM) device that detects, analyzes, and identifies (RF) emissions from enemy systems. As a receive-only system, it passively intercepts signals without transmitting any emissions, thereby maintaining the stealth of the host platform. This core functionality positions the RWR as an essential component of defensive , focused on threat awareness rather than disruption. The primary purpose of an RWR is to deliver timely warnings to operators, such as aircraft pilots, regarding potential threats including radar-guided missiles, anti-aircraft artillery, and radars. By alerting crews to incoming dangers, it enables rapid responses like evasion tactics, deployment of countermeasures, or adjustments to mission profiles, ultimately enhancing survivability in hostile environments. In fulfilling this role, RWRs boost through threat classification—differentiating modes such as search, acquisition, and tracking—while estimating key signal parameters like , , and type. Threats are then prioritized based on lethality, with visual and audio cues provided to the for immediate . Unlike active jammers that emit signals to interfere with radars and risk detection, RWRs remain covert by design. RWRs are predominantly integrated into military platforms such as fighter jets and helicopters.

Operating Principles

Radar warning receivers (RWRs) operate by passively intercepting and analyzing radio frequency (RF) emissions from hostile radars to provide timely threat warnings. The core detection process begins with specialized antennas that capture incoming RF signals across broad frequency bands, typically spanning 2 to 18 GHz for many operational systems, though modern variants extend coverage up to 40 GHz to address advanced threats in higher bands like Ka-band (27–40 GHz). These signals are then down-converted to intermediate frequencies (IF) using superheterodyne receivers, which offer high sensitivity (often -50 to -60 dBm) and selectivity for processing weak emissions at long ranges. Once captured, the RWR analyzes key signal characteristics to classify the emitter. Critical parameters include (PRF), which indicates the rate of pulses per second and helps distinguish search from tracking modes; (PW), revealing the radar's resolution and type; scan type, such as circular or sector patterns inferred from signal modulation over time; and modulation schemes like frequency agility or phase coding, which denote advanced operational modes. These attributes are extracted through to determine the radar's mode, platform, and potential intent, enabling differentiation between benign and hostile sources. Threat evaluation relies on comparing the analyzed parameters against an onboard emitter identification (EID) library, which stores signatures of known radar systems—such as the SA-6 (SAM) radar's distinct PRF and versus a fighter aircraft's . Matches prioritize threats based on lethality, range, and bearing, with libraries often containing over 1,000 entries updated via mission data loads. The minimum detectable signal strength is governed by the (SNR) threshold, typically requiring SNR > 1 (or 0 ) for reliable detection, though practical systems aim for 3–10 to reduce false alarms. The underlying physics is captured in the SNR for passive interception: \text{SNR} = \frac{P_t G_t G_r \lambda^2}{(4\pi)^2 R^2 k T B F L} where P_t is the radar's transmitted power, G_t and G_r are the transmitting and receiving antenna gains, \lambda is the wavelength, R is the range to the emitter, k is Boltzmann's constant, T is the system noise temperature, B is the receiver bandwidth, F is the noise figure, and L accounts for losses—this form derives from the one-way power received at the RWR, emphasizing sensitivity to emitter power and geometry over the two-way radar echo. Upon identification, the RWR generates outputs to the , including audio tones that vary by (e.g., beeps for high- tracking modes matching the emitter's PRF) and visual displays showing symbols on a circular bearing indicator, with icons denoting threat level, type, and . These cues integrate with interfaces for immediate , often triggering automated countermeasures. A key limitation of RWRs is their reduced effectiveness against low-probability-of-intercept (LPI) s, which employ techniques like hopping, low peak power, or wide bandwidths to minimize detectable emissions, thereby lowering the SNR below detection thresholds and evading .

Technical Components

Antennas and Receiving Systems

warning receivers (RWRs) employ specialized to capture incoming signals across wide bands, with spiral being particularly prevalent due to their broadband capabilities spanning 2–18 GHz and for effective detection of diverse emissions. , such as spiral or horn arrays, provide 360° azimuthal coverage essential for all-aspect threat detection, while directional are used in configurations requiring precise bearing measurements. These designs ensure sensitivity to pulsed signals in environments, often integrating cavity-backed structures to enhance gain and isolation. To achieve comprehensive spatial awareness, RWR systems typically utilize multiple antennas arranged in 4–8 quadrants on platforms, enabling 360° coverage and partial coverage through overlapping fields of view. This multi-antenna setup divides the surrounding into sectors, allowing simultaneous monitoring of threats from various directions and improving localization accuracy in dynamic scenarios. Naval and ground-based RWR variants may employ additional elements for broader angles, ensuring robust performance against low- surface threats. The receiving chain in an RWR begins with low-noise amplifiers (LNAs) to amplify weak incoming signals while minimizing added noise, typically achieving noise figures below 3 in modern implementations. These are followed by mixers that perform down-conversion from (RF) to an (IF) using superheterodyne architecture, facilitating easier signal handling and filtering. In digital RWRs, analog-to-digital converters (ADCs) then digitize the IF signals for subsequent processing, enabling high-resolution analysis of pulse characteristics. Key design challenges for RWR antennas and receiving systems include to fit constrained spaces without compromising , resistance to (EMI) from onboard systems, and managing high dynamic ranges—often exceeding 80 dB—to handle signals varying from distant weak emissions to nearby intense ones. These factors demand robust shielding and adaptive gain control to maintain across operational environments. The evolution of RWR receiving systems has progressed from vacuum tube-based designs in early models, which suffered from high power consumption and limited bandwidth, to solid-state implementations using (GaAs) and (GaN) technologies for enhanced efficiency and sensitivity. Modern GaAs or GaN LNAs provide noise figures under 3 dB, significantly improving detection of low-probability-of-intercept radars compared to historical receivers with figures often above 10 dB. Some advanced RWR antennas incorporate monopulse techniques to estimate the angle of arrival (AOA) with accuracies around 10°, leveraging or comparisons across antenna elements for rapid threat bearing determination. This method enhances directional precision without sequential scanning, critical for real-time evasion maneuvers.

Signal Processing and Threat Identification

The signal processing in radar warning receivers (RWRs) begins with (DSP) techniques applied to digitized (RF) inputs, where raw pulses are analyzed to extract pulse descriptor words (PDWs). Each PDW encapsulates key parameters such as time of arrival (TOA), (PW), (RF), pulse amplitude (PA), and pulse repetition interval (PRI), enabling the system to characterize individual radar pulses. This extraction occurs via field-programmable gate arrays (FPGAs) or dedicated processors that convert analog RF signals into a digital stream, normalizing parameters for efficient handling— for instance, frequencies in MHz and pulse durations in microseconds. A critical step in the is deinterleaving, which separates overlapping PDWs from multiple emitters in interleaved pulse trains to reconstruct coherent signal streams for each source. Algorithms employ clustering methods, such as chain algorithms that compute distances between PDW parameters like start frequency (SF), end frequency (EF), and TOA, grouping pulses into emitter-specific clusters while accounting for challenges like pulse overlap, dropped pulses, or multipath effects. This process is essential in electronic support measures (ESM) environments, where RWRs must sort signals from stable PRI emitters to avoid misassociation. Once PDWs are extracted and deinterleaved, they are matched against a library—a comprehensive database of known radar signatures compiled from global on adversary systems. These libraries, often containing over 1,000 entries representing emitter modes from various , store parametric profiles including ranges, PRI patterns, scan types, and modulation schemes for systems like surface-to-air missiles (SAMs) and airborne . Updates occur through mission data files (MDFs) generated via the Integrated Reprogramming (EWIR) process, with annual revisions or expedited loads (24-72 hours) to incorporate new , ensuring the library reflects current operational environments. Identification relies on , where observed PDWs are compared to library entries using similarity metrics on parameters like and PRI. Core algorithms enhance detection and classification reliability. Constant false alarm rate (CFAR) processing maintains a stable detection threshold by estimating local levels from surrounding cells, adapting to varying while preserving a fixed probability of false alarms—typically around 10^{-6}—to identify pulses amid clutter. In advanced systems, techniques, such as k-nearest neighbors (KNN) or support vector machines (SVM), enable adaptive by training on library data to recognize subtle variations in emitter signatures, achieving accuracies exceeding 92% for new parameter sets. These methods weigh parameters like (highest importance) and to prioritize matches. Threat identification often employs Bayesian inference as a statistical foundation for probabilistic matching, computing the posterior probability of a specific threat given observed parameters T_i (e.g., RF, PRI). The key equation is: P(\text{Threat} | T_i) = \frac{P(T_i | \text{Threat}) \cdot P(\text{Threat})}{P(T_i)} Here, P(T_i | \text{Threat}) is the likelihood of observing parameters under a hypothesized threat, P(\text{Threat}) is the prior probability based on mission context, and P(T_i) normalizes over all possibilities; this framework quantifies confidence in library matches, reducing ambiguity in noisy data. Processed threats are presented on symbolic displays for pilot awareness, using icons like a diamond for high-priority SAM sites and a spike for fighter locks or launches, positioned by on a circular or tabular interface. Alerts employ audio tones and visual flashing, with priority queuing derived from signal strength estimates (approximating range via received power) and lethality assessments, escalating from search modes to or warnings. Significant challenges arise in dense signal environments exceeding 100 emitters, where interleaving and crowding degrade deinterleaving accuracy, potentially overwhelming processors and increasing misidentification rates. Unknown or novel threats, not matching entries, trigger "growler" alerts—distinct warnings for unrecognized signals—prompting manual analysis or countermeasures while highlighting the need for adaptation.

Historical Development

Origins in World War II and Early Cold War

The origins of radar warning receiver (RWR) technology emerged during World War II as Allied forces sought passive means to detect and evade German radar-directed threats. The British Boozer system, developed in the early 1940s and designated ARI 1618, was fitted to RAF bombers to intercept emissions from German Würzburg radars, which were used for fire control and targeting night fighters. This simple receiver-based device activated a warning light or indicator upon detecting the characteristic Würzburg signals in the 480–600 MHz band, alerting aircrews to imminent targeting without providing directional information. Post- advancements in the United States built on these passive detection concepts, transitioning tail warning radars toward electronic support measures (ESM) for broader threat awareness. The AN/APS-13, originally a lightweight active tail warning radar introduced late in , saw continued use during the (1950–1953) on U.S. fighters like the F-86 Sabre for basic rear-hemisphere detection of approaching aircraft up to 800 yards. Operating in the UHF band around 410–420 MHz, it evolved into passive ESM configurations that emphasized signal interception over transmission, laying groundwork for dedicated RWRs amid emerging jet-age threats. The Cold War's intensification, particularly the deployment of Soviet S-75 (NATO SA-2 Guideline) surface-to-air missiles in the early , accelerated the need for specialized RWRs to counter radar-guided air defenses. These systems, operationalized by from 1965, prompted rapid U.S. development of dedicated receivers like the AN/APR-25 (S/C/X-band radar homing) and AN/APR-26 (missile launch warning), fielded on aircraft such as the F-4 Phantom and F-105 Thunderchief from 1965 through 1972. Integrated as the Radar Homing and Warning (RHAW) suite, these analog devices detected Fan Song acquisition and tracking radars associated with SA-2 launches, providing audio and visual alerts to enable evasive maneuvers. A pivotal deployment came in 1967, when the U.S. Air Force retrofitted AN/APR-25/26 RWRs onto F-4 Phantoms operating over , coinciding with intensified Rolling Thunder operations. This integration allowed pilots to detect SAM radar locks, significantly reducing aircraft losses to radar-guided missiles by enabling timely warnings and countermeasures deployment. Early RWR-equipped missions demonstrated improved survivability, with post-deployment analyses crediting the systems for averting numerous potential shootdowns amid the SA-2 threat. Despite these advances, early RWRs suffered from inherent limitations, including narrowband operation that covered only specific frequency ranges, reliance on analog processing without digital signal analysis, and absence of emitter identification, rendering them vulnerable to false alarms triggered by friendly or unrelated radar emissions. These constraints often overwhelmed crews with ambiguous warnings in cluttered electromagnetic environments, limiting tactical utility until subsequent refinements. Marking a key milestone, the AN/APR-36 entered operational service in 1969 as the first dedicated U.S. Air Force RWR, succeeding the APR-25/26 with enhanced analog circuitry that provided approximate bearing to detected threats via a display, though it still omitted specific threat typing or prioritization. Deployed initially on F-4 variants, this system represented the pre-digital pinnacle of RWR evolution before the 1970s shift to integrated digital processing.

Technological Generations

The evolution of radar warning receivers (RWRs) has progressed through distinct technological generations, each marked by advancements in signal detection, processing, and threat assessment capabilities. The first generation, spanning the 1960s to 1970s, relied primarily on analog systems using crystal-video detection for basic radar signal interception and bearing determination. These early RWRs, such as the introduced in 1970, operated over limited fixed frequency bands and suffered from high false alarm rates due to rudimentary filtering, often requiring manual crew interpretation for threat prioritization. The second generation, emerging in the to , introduced initial digital processing to enable basic signal identification and reduce false alarms through pulse descriptor word (PDW) analysis, which examined parameters like pulse repetition interval and . This shift from purely analog to hybrid digital architectures allowed for wider coverage, typically 2–12 GHz, improving to diverse emissions. Systems in this era marked a foundational milestone in real-time processing, transitioning RWRs from passive detectors to more actionable warning tools. By the third generation in the to , RWRs incorporated fully integrated receivers with programmable threat libraries for automated emitter classification, alongside 360° azimuthal coverage via multi-antenna arrays. Innovations included mode recognition to distinguish search from tracking patterns, enhancing pilot . The U.S. Navy's AN/ALR-67, entering service around 1978, exemplified this generation as the first to employ advanced pulse train deinterleaving and squadron-level software reprogramming for adaptability. The fourth generation, from the to , leveraged software-defined radios (SDRs) for flexible, multi-threat handling across expanded spectra, incorporating geolocation features to estimate emitter positions via time-difference-of-arrival techniques. These systems achieved high identification accuracy, often exceeding 95% for known threats, through enhanced and integration with countermeasures suites. Representative examples include variants of the AN/APR-39 family, such as the AN/APR-39D(V)2, which provided precise threat discrimination and operational growth for electronic attack. Fifth-generation RWRs, developed from the 2010s onward, integrate cognitive systems using (AI) and to detect and classify unknown or novel threats in , adapting algorithms dynamically without predefined libraries. These advancements enable reduced size and weight for unmanned aerial vehicles (UAVs) while maintaining robust performance against agile, low-probability-of-intercept radars. Recent demonstrations, such as Raytheon's AI/ML-powered RWR tested in 2025, highlight cognitive capabilities that prioritize threats autonomously, marking a shift toward autonomous decision support in contested environments.

Systems and Applications

Early and Mid-Generation Examples

One prominent example from the 1970s is the AN/ALR-56 radar warning receiver, which was integrated into the F-15 Eagle fighter upon its entry into operational service in 1976 and was later integrated into the F-16 Fighting Falcon. This digital system provided 360-degree azimuth coverage through multiple antennas mounted on the aircraft's extremities, enabling rapid detection and identification of over 20 distinct threat emitters, including surface-to-air missile radars. Deployed extensively by the U.S. Air Force, the AN/ALR-56 demonstrated its effectiveness during the 1991 Gulf War, where F-15s equipped with it evaded numerous radar-guided threats in high-density environments. Its performance included long-range detection exceeding 100 kilometers for typical SAM radars, with a low false alarm rate to minimize pilot distraction. In the , the AN/ALR-67 emerged as a third-generation RWR, entering service with the U.S. Navy's F/A-18 Hornet in 1983 as part of an integrated electronic countermeasures suite. This system featured advanced to handle frequency-agile and pulsed-Doppler radars, providing visual and aural alerts for threat bearing, type, and priority while interfacing with jamming pods for coordinated responses. Widely adopted across platforms, the AN/ALR-67 was exported to allies including and , enhancing in multinational operations. By the late 1990s, thousands of units had been produced, solidifying its role in carrier-based aviation. The 1990s saw upgrades to systems like the AN/APR-39, a compact RWR tailored for U.S. Army rotary-wing such as the AH-64 Apache and UH-60 Black Hawk, with significant enhancements introduced in the mid-1990s through the AN/APR-39A(V)1 variant. This digital upgrade incorporated a programmable threat library optimized for low-altitude operations, automatically classifying signals from anti- and short-range missiles while delivering 360-degree coverage via quadrant antennas. Its lightweight design suited the space constraints of helicopters, enabling evasive maneuvers and deployment against ground-based threats. These early and mid-generation RWRs, while revolutionary in transitioning from analog to processing, faced limitations against emerging low-probability-of-intercept (LPI) radars in the 1990s, which used low-power or agile emissions to evade detection by pulse-based receivers.

Modern and Advanced Systems

In the , the AN/ALR-69A radar warning underwent significant upgrades for the U.S. , entering the system development and demonstration phase with flight tests beginning in late 2005. This all- system replaced the legacy AN/ALR-69, featuring a / that enabled software-reprogrammable libraries for improved detection , accuracy in dense environments, and overall reliability. Initial spirals incorporated GPS integration to provide single-ship geographic location of emitters, supporting precise targeting with GPS-guided munitions. By the 2010s, multiservice systems like the AN/APR-39E(V)2 advanced the field with fully architecture for enhanced threat discrimination across rotary- and fixed-wing platforms. With development contracted in 2019 and initial production beginning in 2024, achieving initial operational capability in 2025, it offered 360-degree coverage, instantaneous wideband frequency agility from 0.5 to 40 GHz, and digital RF memory capabilities for realistic of countermeasures against agile threats. This system improved mission survivability by automatically detecting, identifying, and prioritizing emitter types, bearings, and lethality levels in complex electromagnetic environments. Entering the 2020s, artificial intelligence and machine learning integration marked a leap in RWR capabilities, exemplified by Raytheon's Cognitive Algorithm Deployment System (CADS) tested on an F-16 in late 2024 with procurement expected in early 2025. This upgrade embeds AI/ML processing at the sensor level using cognitive algorithms to sense, identify, and prioritize threats in real time with minimal latency, even for unknown signals, enhancing aircrew decision-making on legacy platforms. Similarly, BAE Systems' AN/ALR-56M, with its 2020 processor modernization, delivers broad-spectrum, long-range detection and adaptive filtering to counter advanced radar threats, including those associated with hypersonic missiles, on aircraft like the C-130J Super Hercules. Modern RWRs emphasize multi-spectral operation to cover diverse bands and types, alongside reductions in size, weight, and power (SWaP) for seamless integration into constrained platforms. In fifth-generation like the F-35, the radar incorporates integrated electronic support measures (ESM) functions, fusing radar warning data with passive sensing for comprehensive awareness without dedicated standalone RWR hardware. These systems have seen deployment in high-threat operations. Internationally, India's DRDO-developed DR-118 indigenous RWR, rolled out in the for the Su-30MKI fleet, detects, classifies, and geolocates radar emitters to bolster resilience against regional adversaries. As of November 2025, the system has been rolled out across the Indian Air Force's Su-30MKI fleet.

Integration and Future Trends

Countermeasures Integration

Radar warning receivers (RWRs) integrate with electronic countermeasures () systems, such as jammers and /flare dispensers, to enable automated responses to detected threats. In airborne platforms, RWRs provide real-time threat data to ECM jammers like the tactical jamming system, which is pod-mounted on aircraft such as the EA-18G Growler for noise jamming on identified threat frequencies. This integration allows the RWR to cue the jammer automatically upon threat identification, enhancing defensive capabilities against radar-guided missiles. Additionally, RWR outputs trigger and dispensers, such as the system, for expendable decoy deployment to seduce incoming threats. Platform-specific implementations vary by operational domain. In airborne systems, the F-35 Lightning II exemplifies where RWR data merges with the Distributed Aperture System () to create a unified threat picture, automatically prioritizing cues for ECM activation or pilot maneuvers. Naval applications feature shipboard electronic support measures (ESM) like the AN/SLQ-32, which incorporates RWR functions to detect threats and cue integrated countermeasures, including decoy launchers and jammers for surface vessel protection. Ground vehicles, such as tanks, employ limited RWR integration due to terrain constraints and lower radar threat density, often relying on complementary laser warning receivers rather than full RF spectrum coverage for ECM triggering. The operational workflow begins with RWR detection of radar emissions, followed by for threat identification, which then triggers responses such as frequency-specific or chaff/ dispensation. This sequence provides pilots or operators with maneuver advice, such as evasive turns, based on geolocated threat data. In integrated suites like the EA-18G Growler, this automation reduces response times to threats, enabling countermeasures deployment in under one second to improve survivability against agile radar systems. Despite these advantages, challenges persist in data fusion for networked environments, where RWR intelligence is shared via tactical data links like to coordinate multi-platform efforts. Such sharing enhances collective defense but risks and latency in high-density threat scenarios. Another issue is avoiding self-jamming, where onboard emissions could degrade the RWR's own detection sensitivity, necessitating advanced frequency management techniques.

Emerging Technologies and Challenges

Recent advancements in radar warning receiver (RWR) technology are leveraging (AI) and (ML) to enable real-time adaptation to novel threats, surpassing traditional library-based classification methods. For instance, RTX's demonstrated the first AI/ML-powered RWR in February 2025, utilizing the Cognitive Deployment System (CADS) to detect, classify, and prioritize enemy radar signals dynamically without relying solely on predefined emitter libraries. This cognitive approach employs algorithms that learn from incoming signals in flight, enhancing aircrew on fourth-generation . In 2025 flight tests on such fighters, the system achieved faster threat identification and prioritization compared to conventional RWRs, improving pilot response times and overall survivability. The integration of () technology is further advancing RWR sensitivity and bandwidth, allowing detection of low-probability-of-intercept (LPI) and stealthy emissions. -based amplifiers enable noise figures as low as 2.5 and operation across wider bands, supporting coverage up to millimeter-wave regimes for countering advanced threats. Key challenges persist in countering adaptive adversaries, including cognitive s that alter waveforms in and drone swarms employing coordinated . Cybersecurity vulnerabilities in updatable threat libraries expose RWRs to remote or denial-of-service attacks, necessitating robust and secure over-the-air updates. Additionally, international export controls on dual-use and components hinder technology sharing among allies, complicating joint development efforts. Looking ahead, future RWR trends emphasize miniaturization for unmanned aerial vehicles (UAVs) and , where compact, low-power systems integrate into swarming operations. Multi-domain architectures will fuse RWR data across air, sea, and space platforms for holistic threat awareness. Driven by rising hypersonic threats, the broader market, including RWR components, is projected to expand significantly, with related drone sectors growing from $4.15 billion in 2025 to $6.69 billion by 2030.

References

  1. [1]
    Radar Warning System - EMSOPEDIA
    The Radar Warning Receiver (RWR) systems have the tasks to detect the E.M. Signals emitted by radar systems and to issue a warning when the intercepted ...
  2. [2]
    Understanding Radar Warning Receivers and… - Duotech Services
    Apr 4, 2025 · An RWR is an advanced electronic system designed to detect, identify, and analyze radar signals emitted by tracking and targeting systems.
  3. [3]
    RADAR WARNING RECEIVERS AND DEFENSIVE ELECTRONIC ...
    While the primary function of the RWR is detection of threats to facilitate evasion, the RWR can also be used to support ECM (jammers) which are another key ...<|control11|><|separator|>
  4. [4]
    AN/APR-39 Digital Radar Warning Receiver Family
    This fully digital system provides 360-degree coverage to automatically detect and identify threat types, bearing, and lethality.Apr-39e(v)2 · An/apr-39e(v)2 Benefits · In The News
  5. [5]
    None
    ### Summary of Radar Warning Receiver (RWR) from the Document
  6. [6]
    What is Electronic Warfare? | L3Harris® Fast. Forward.
    This is the system's “receive” capability, and it is usually performed by a subsystem called radar warning receiver (RWR). Address threats head on. If the RWR ...
  7. [7]
    [PDF] THE RADAR WARNING STORY
    The need for aircraft self-protection assets was the driving force behind a seminar held in. August 1965, and led to a recommendation for the development of ...
  8. [8]
    [PDF] Electronic Warfare Fundamentals
    radar warning receiver (RWR) will provide no attack warning unless the threat uses some detectable radar energy for acquisition prior to launching an IR ...<|control11|><|separator|>
  9. [9]
    Radar Warning Receiver Market Size, Share & Growth Forecast 2035
    Sep 18, 2025 · Frequency Band. Ka-Band (27–40 GHz); K-Band (18–27 GHz); Ku-Band (12-18 GHz); X-Band (8–12 GHz); C-Band (4–8 GHz); S-Band (2–4 GHz); L-Band (1–2 ...
  10. [10]
    None
    ### Radar Equation for Signal-to-Noise Ratio (SNR) in Detection
  11. [11]
    Spiral Antennas - CAES
    CAES is a leading designer and manufacturer of spiral antennas. CAES Spiral Antennas are standard equipment on advanced electronic warfare systems worldwide.
  12. [12]
    AN/APR-39 Radar Warning Receiver (RWR) - GlobalSecurity.org
    Jul 7, 2011 · The system retained the former AN/APR-39A low band vertically polarized blade antenna. The new, more sensitive, circularly polarized spiral ...
  13. [13]
    [PDF] am-423 cavity-backed spiral antenna - L3Harris
    The AM-423 is a planar, cavity-backed spiral antenna operating from 2-18 gigahertz. Left-hand circular polarization (LHCP) is standard, but right-hand ...
  14. [14]
    Emitter Location with Azimuth and Elevation Measurements Using a ...
    Jun 8, 2021 · Fighter aircraft RWR systems often use four antennas to provide 360° angular coverage, while naval RWR systems often use six or eight antennas.
  15. [15]
    (PDF) Emitter Location with Azimuth and Elevation Measurements ...
    Oct 15, 2025 · ... RWR systems often use four antennas to provide 360. ◦. angular. coverage, while naval RWR systems often use six or eight antennas. Threat ...
  16. [16]
    [PDF] GAAS: Evolution of Transceiver Design from Radar to Imaging
    The LNAs have a noise figure of less than 2.5dB but significant gain slope across the frequency band 35GHz to 45GHz. At 45GHz the Gain from a single LNA ...Missing: vacuum tube
  17. [17]
    [PDF] Optimum Symmetrical Number System Phase Sampled Direction ...
    ANALOG TO DIGITAL CONVERSION (ADC). The process of converting a continuous-time (analog) signal to a digital sequence that can be processed by a digital ...
  18. [18]
    [PDF] Commercially Available Low Probability of Intercept Radars and ...
    Sep 30, 2014 · The instantaneous dynamic range of a linear receiver is between. 50 and 60 dB while that of a log-video receiver is about 80 dB. The sensitivity ...
  19. [19]
    [PDF] Electronic Countermeasures (ECM) and Acoustic ... - DTIC
    The performance of an RWR is usually discussed in terms of sensitivity, dynamic range, probability of intercept (POI) and throughput rate. Short definitions of ...
  20. [20]
    [PDF] Electronic Warfare and Radar Systems Engineering Handbook - DTIC
    Jun 1, 2012 · ... Receiver Shadow Time. RT. Remote Terminal, Termination. Resistance, or Receiver/Transmitter. (also R/T). RUG. Radar Upgrade. RWR. Radar Warning ...
  21. [21]
    Microwaves101 | Noise Figure - Microwave Encyclopedia
    Noise figure is the noise factor, expressed in decibels: NF (decibels)=noise figure =10*log(F). Noise figure is more often used in microwave engineering.
  22. [22]
    [PDF] Challenge of Future EW System Design - DTIC
    dedicated RWR antennas (around 10 degrees AOA accuracy) for use on a 100 % duty- cycle. I hope this helps. Your question is a very good one, and more work ...<|control11|><|separator|>
  23. [23]
    Accuracy improvement in amplitude comparison‐based passive ...
    May 1, 2020 · This work focuses primarily on monopulse method of direction finding. Monopulse technique means that DOA information can be extracted from every ...
  24. [24]
    [PDF] IT'S A COMPLEX WORLD 'RADAR DEINTERLEAVING' - Armms
    The digital signal processing in the FPGA converts the received analogue pulse into a digital stream of pulse descriptor words (PDW). The pulse descriptor word ...Missing: warning | Show results with:warning
  25. [25]
    Mpsoc Fpga-Based Radar Warning Receiver And Deinterleaving ...
    Feb 22, 2024 · An RWR's primary function is to identify unknown radar signals and produce a PDW used to classify and sort signals for further processing, ...
  26. [26]
    Deinterleaving for radar warning receivers with missed pulse ...
    A method for deinterleaving of intercepted signals having small number of pulses that belong to stable or jitter pulse repetition interval (PRI) types in ...Missing: digital | Show results with:digital
  27. [27]
    [PDF] Machine Learning Application for Mission Data Reprogramming
    Nov 22, 2021 · For example, a Radar Warning Receiver uses MD to identify a threat and a radar jammer uses it to employ an appropriate countermeasure. The ...Missing: signatures | Show results with:signatures
  28. [28]
    [PDF] Outsmarting Agile Adversaries in the Electromagnetic Spectrum
    ... mission data file (MDF) or threat library. Page 13. 3 the USAF is exploring how best to achieve adaptive and cutting-edge EMS capabilities.15 The need for ...
  29. [29]
    A Novel Machine Learning Approach for Optimizing Radar Warning ...
    Oct 21, 2024 · This study presents a machine learning-based approach for emitter identification within RWR systems, leveraging a comprehensive radar signal library.
  30. [30]
    Constant False Alarm Rate (CFAR) Detection - MATLAB & Simulink
    This example introduces constant false alarm rate (CFAR) detection and shows how to use CFARDetector and CFARDetector2D in the Phased Array System Toolbox.Missing: warning | Show results with:warning
  31. [31]
    [PDF] A Comparison of Bayesian and Belief Function Reasoning
    A Bayesian Network for the Anti-Air Threat Identification Problem. Radar Warning Receiver (RWR). Visibility (V). Threat Effective? (TE). ML_Indicator (ML).
  32. [32]
    RWR - DCS World Wiki - Hoggitworld.com
    Sep 22, 2020 · Threat Symbology. The following are the indicated threat symbols. RWR-Diamond.png - Primary threat as dictated by the RWR. RWR-Track.png ...
  33. [33]
    https://www.tracesofwar.com/thewarillustrated/227/now-it-can-be-told-bomber-command-and-the-war-in-the-ether.asp
  34. [34]
    Now It Can Be Told! - Bomber Command and the War in the Ether
    An early attempt to deal with enemy radar by use of a warning receiver was christened “Boozer”. In its original form it was simply a receiver which lit a ...
  35. [35]
    Radar Ancillary Equipment, Indicator Type 181, Type R1618 and ...
    British radar indicator unit Type 181 for Type R1618 and R1626 Boozer airborne radar warning systems. Stores reference 10Q/16010.Missing: WWII | Show results with:WWII
  36. [36]
    Bogey Six O'clock!: The AN/APS-13 Tail Warning Radar | Hackaday
    Oct 31, 2024 · Fitted to aircraft like the P-51 Mustang and P-47 Thunderbolt, the AN/APS-13 warns the pilot with a light or bell if the aircraft comes within 800 yards from ...
  37. [37]
    The AN/APS-13 Tail Warning Radar Conundrum
    Aug 2, 2023 · This is a story of the RAF Monica (ARI 5664) tail warning radar and its US clone known under the nomenclature of AN/APS-13.
  38. [38]
    The F-4's AN/APR-25 & 26 Radar Homing & Warning System
    Jun 15, 2019 · The radar homing and warning system (RHAW) was a very important black box installed in F-4s that flew in combat in the Vietnam War.
  39. [39]
    To Save Crews from Deadly Missiles Over Vietnam, The U.S. Air ...
    Sep 5, 2021 · Three months later the California company installed the first AN/APR-26 radar-warning receivers on Navy fighters flying over North Vietnam.
  40. [40]
    https://www.dote.osd.mil/Portals/97/pub/reports/FY2024/army/2024anapr39e.pdf
  41. [41]
    RTX's Raytheon demonstrates first-ever AI/ML-powered Radar ...
    Feb 24, 2025 · RTX's Raytheon demonstrates first-ever AI/ML-powered Radar Warning Receiver for 4th generation aircraft. New technology will enhance aircrew ...
  42. [42]
    F-15 Eagle > Air Force > Fact Sheet Display - AF.mil
    The first F-15A flight was made in July 1972, and the first flight of ... ALR-56C radar warning receiver and ALQ-135 countermeasure set. The final 43 ...
  43. [43]
    RWR: Radar Warning Receivers (AN/ALR 56) - BAE Systems
    The primary function of the RWR is to detect potentially hostile radars, providing pilots and crews enhanced situational awareness and improved ...
  44. [44]
    AN/ALR-56M Radar Warning Receiver (RWR)
    Jan 9, 1999 · The ALR-56M is designed to provide improved performance in a dense signal environment and improved detection of modern threat signals.
  45. [45]
    AN/ALR-56M Radar Warning Receiver Safeguards F-16 Fighting ...
    Jul 10, 2024 · The AN/ALR-56M provides broad-spectrum, long-range threat detection and adaptive filtering to isolate threat signals in dense signal ...
  46. [46]
    AN/ALR-67 Advanced Special Receiver - GlobalSecurity.org
    Jul 7, 2011 · The AN/ALR-67(V)2 is a radar threat warning system. It has three different types of receivers; a broadband crystal video receiver, a super- ...
  47. [47]
    AN/ALR-67
    The ALR-67 is the US Navy standard warning system installed on carrier-based, front-line, combat-coded F/A-18C/D/E/F aircraft. It is a compact, lightweight and ...<|control11|><|separator|>
  48. [48]
    [PDF] NSIAD-94-4 Electronic Warfare: Costly Radar Warning Receiver ...
    Nov 29, 1993 · Advanced Special Receiver, now called the ALR-67(V)3, to replace the improved version of the ALR-67. The Air Force's ALR-69, used in the F-16 ...
  49. [49]
    F/A-18 threat protection systems contract awarded - NAVAIR
    The AN/ALR-67(V)3 RWR is a radar warning receiver that provides visual and aural alerts to F/A-18E/F aircrew upon detection of ground based, ship based, or ...
  50. [50]
    AN/APR-39 Radar Warning Receiver (RWR)
    Feb 10, 2000 · The AN/APR-39 Digital Threat Warning System monitors the environment for pulsed radar signals, characterize and identify them, and alert the crew to the ...<|separator|>
  51. [51]
    RADAR WARNING RECEIVER (RWR) AN/APR-39A (V)2
    The AN/APR-39A (V)2 is a multi-Service (Navy/USMC, and Special Operations Force) next generation RWR upgrade to the existing AN/APR-39 (V1).Missing: history | Show results with:history
  52. [52]
    [PDF] ALR-69A Radar Warning Receiver (RWR) - GlobalSecurity.org
    ALR-69A RWR is designed to improve the Air Force's primary RWR system, the legacy ALR-69. • It is designed for fighter and transport aircraft. Lead platforms.Missing: upgrades reprogrammable GPS geolocation
  53. [53]
    AN/APR-39 - Deagel
    The AN/APR-39E(V)2, formerly known as the Modernized Radar Warning Receiver (MRWR), is a next generation radar warning system intended for use by the US Army.
  54. [54]
    [PDF] AN/ALR-56M Modernized processor upgrade - BAE Systems
    The upgraded AN/ALR-56M advanced Radar Warning Receiver (RWR) enhances aircrew survivability by continuously detecting and intercepting. RF signals in ...
  55. [55]
    AN/APG-81 Active Electronically Scanned Array (AESA)
    In air-to air-combat, the AN/APG-81 provides long range capability allowing the pilot to detect, track, identify and shoot multiple threat aircraft before the ...
  56. [56]
    ISIS drones are attacking U.S. troops and disrupting airstrikes in ...
    Jun 14, 2017 · ... Syria. The drone attacks around Raqqa come as U.S. Special Operations forces contend with larger unmanned aerial threats in southern Syria.
  57. [57]
    https://www.navair.navy.mil/product/ALQ-99-Tactical-Jamming-System
  58. [58]
    ALQ-99 Tactical Jamming System - NAVAIR
    The ALQ-99 Tactical Jamming System (TJS) is an external carriage airborne electronic attack capability for the EA-18G Growler aircraft used against radar and ...
  59. [59]
    [PDF] EA-6B & EA-18G EW (ALQ-99 & -218 - Teal Group
    Mar 29, 2018 · The NGJ-MB consists of two pods mounted under the EA-18G air- craft wings that integrate with the. AN/ALQ-218 radio frequency re- ceiver (radar ...
  60. [60]
    ALE-47 Airborne Countermeasures Dispenser System
    The ALE-47 is a top chaff and flare system that uses EW sensors to defeat IR and RF missiles, and is used by the U.S. military and allies.
  61. [61]
    How the F-35 Connects the Battlespace - Lockheed Martin
    May 14, 2025 · Some of the key technologies that enable the F-35 to do this include: Active Electronically Scanned Array Radar: The F-35's AN/APG-81 AESA ...
  62. [62]
    [PDF] F-35 Lightning II
    May 17, 2012 · • Integrated Sensor. Fusion. • Net-Enabled. Operations. • Peace ... Sensor Fusion. F-35. APG-81. APG-81. RWR/ESM. Yes. EOTS. EOTS. EOTS. DAS. Yes.
  63. [63]
    AN/SLQ-32 Electronic Warfare (EW) system - Military Analysis Network
    Jun 30, 1999 · The AN/SLQ-32(V) provides operational capability for early warning of threat weapon system emitters and emitters associated with targeting platforms.Missing: ESM RWR
  64. [64]
    [PDF] Systems Engineering Approach To Ground Combat Vehicle ... - DTIC
    Examples include radar warning receivers (RWR) on aircraft, as well as laser warning devices (LWD) on ground vehicles. Having integrated situational awareness ...
  65. [65]
    [PDF] AIRBORNE RADAR JAMMERS
    ALQ-99 is US Navy's primary standoff jamming system, flown on EA-6B Prowler and EA-18G. Growler electronic attack aircraft; multi-pod system covering ...
  66. [66]
    Raytheon tests AI/ML-powered RWR - Air Force Technology
    Feb 25, 2025 · RTX's Raytheon has demonstrated the first AI/ML-powered RWR system designed for fourth-generation fighter jets.Missing: adaptive | Show results with:adaptive
  67. [67]
    Raytheon tests AI-integrated Radar Warning Receiver
    Feb 28, 2025 · According to Raytheon, the system can process large amounts of information with minimal delay, providing aircrew with faster threat ...Missing: fighters response
  68. [68]
    MACOM IMS 2025 Product Preview - Radar
    Jun 12, 2025 · Leveraging MACOM's GaN-on-SiC process technology ... The receive side can provide 16 dB of gain with a 2.5 dB of noise figure and 21 dBm OIP3.
  69. [69]
    Stealth buster? China touts next-gen, quantum radar tech - Asia Times
    Oct 14, 2025 · China claims photon-catching, counter-stealth breakthrough but critics claim tech still more lab curiosity than deployable capability.Missing: RWR figure
  70. [70]
    [PDF] EDF 2024 Call Topic Descriptions.pdf - Defence Industry and Space
    Mar 15, 2024 · countering cognitive radars and threats with unknown waveforms. • Signal detection, recognition and geolocation of targets and threats ...
  71. [71]
    Defense Electronics Market Size, Share | Growth Analysis [2032]
    The defense sector continues to face significant challenges from export restrictions and stringent regulatory frameworks. ... warning systems, radar warning ...
  72. [72]
    https://www.marketsandmarkets.com/blog/AD/drone-uav-payload-market-analysis-2030
  73. [73]
    Hypersonic Weapons Market Size, Share & 2030 Trends Report
    Aug 25, 2025 · The Hypersonic Weapons Market is expected to reach USD 8.24 billion in 2025 and grow at a CAGR of 12.40% to reach USD 14.78 billion by 2030.