Proximity Fuze Research Articles

A Warped-Fast-Fourier-Transform-Based Ranging Method for Proximity Fuze

A Warped-Fast-Fourier-Transform-Based Ranging Method for Proximity Fuze

The Detection Capability of Laser Fuze in Fog, Mist, and Haze Using Monte Carlo Simulations

When choosing a laser wavelength for proximity fuze with high accuracy requirements, the weather condition is a considerable element. Hence, the paper developed a laser detection model in different conditions based on the Monte Carlo method to evaluate the detection capability. As the atmospheric attenuation is a function of the wavelength, there is a conception that the laser pulsed fuze with 1550 nm light suffers from less atmospheric attenuation than 785 or 850 nm laser in all weather conditions (Pratt, 1969). However, in foggy weather (visibility <500 m), the results showed that laser attenuation appeared to be wavelength independent, i.e. the wavelengths of 785 nm, 850 nm, and 1550 nm are equally all attenuated equally by fog. Furthermore, the simulations also allowed the prediction of transmission, as well as the effects of energy scattering and absorption. This paper can provide guidance and reference for the application of laser wavelengths in the laser fuze.

Research on Performance Improvement of Projectile Velocity Measurement Model

This paper studies the existing photoelectric velocimetry model, which assumes that the trajectory is straight and the projectile velocity is uniform and constant in the test area. In the test of muzzle velocity of projectile and the experiment of miss distance of proximity fuze, the influence of air resistance and other factors on the velocity during the flight of projectile is not considered, so there is a big test error in the velocity value. In this paper, an optimized test method of velocity parameters is put forward by deeply studying the aerodynamics of projectile in flight and combining with physical mechanics. Through experiments and simulation studies, it can be proved that the speed parameter value determined by this method is closer to the true value, and the relative error is much smaller than the existing measurement methods, which has certain practical value in practice.

Pulsed Laser Ranging Techniques Based on Digital Signal Processing Methods for Proximity Fuze

Laser fuze systems play an emerging part in military technology bases nowadays. In the paper, a solution is developed to improve the accuracy of the laser rangefinder system in laser fuze without changing the hardware design of the digital signal processor. The proposed algorithm will combine real-time pulse processing techniques used in target range measurement. The new algorithm interpolates returned data using a relatively low sampling rate to a higher one. It applies a cross-correlation technique using high-resolution reference waveform models to restore the position of the super-sampled start and return pulses. Based on the Monte Carlo method and simulating the waveform in the noise environments, 100 trials were judged on the standard deviation of the range estimations. With the presentation of detection performance comparison results between range estimation algorithms of laser fuzes, this paper can provide guidance and references for the application in the proximity fuze.

Calculation model and analysis of laser echo power based on dual‐transmitter and dual‐receiver laser circumferential scanning detection mechanism

AbstractTo ensure that the laser proximity fuze can detect the ground target during the intersection between the laser detection system and the ground target, based on the dual‐transmitter dual‐receiver laser circumferential scanning detection mechanism, we established the constraint functions of scanning frequency and laser pulse frequency without missing measurement. According to the surface characteristics of the plane target, we derived the calculation models of the laser echo power and the minimum detectable echo power of the detection system to the plane target under the random intersection attitude. The calculation function of the angle between adjacent laser beams is obtained based on the minimum detectable echo power. We discussed the relation of the scanning frequency, the laser pulse frequency, the angle between adjacent laser beams and the intersection angle, focused on the influence of the intersection angle and the detection distance on the laser echo power. The simulation experiments were carried out under different laser peak powers and detection distances, the experimental results fully demonstrate that the laser echo power calculation model established in this paper is correct; the detection ability of the system is improved to a certain extent by increasing the laser peak power.

Study on fuze-guidance integration technology for improving air target striking capability of fortification storming/heat missiles

In order to realize air-ground integration strike capability of the fortification storming/HEAT missiles, with the study background of addition of a laser proximity fuze to the missile, this paper proposes a fuze-guidance integration design method based on combination of image guidance and laser proximity fuze detection. By utilizing the missile-target encounter images, the gimbal angle of the seeker, the velocity and attitude of the missile, as well as the bearing and distance of the target detected by the laser proximity fuze, our design method establishes the space geometric equations of the relative motion of the missile and target, and of the equivalent conical plane of the dispersion center of the warhead fragments in the coordinate system of the missile body. Meanwhile, by solving the equations, a fully formulaic optimal time delay model of fuze-warhead matching is obtained, and the optimal detonation time of the warhead is given. The results show that this integration design method can effectively improve the damage effect of the missile on the helicopter target under complex encountering conditions, and realize the integrated air-to-ground strike capability of the fortification storming/HEAT missile.

Experimental and numerical investigation of reinforced concrete slabs under blast loading

The civilian buildings and the military structures have been unexpectedly exposed to the risk of terrorist attacks, particularly in the form of vehicle bombing and other portable detonation devices and explosives. For example, the recent incident happened in Sri Lanka wherein more than 250 people were killed and about 500 people had been injured. The high mobility of these potential threats is also a major challenge to the structural safety of any building. The chances of a full-fledged war with any country albeit low cannot be neglected. During such attacks, the bunkers and protective shelters in the field areas are highly vulnerable to the blast by high explosive rounds of Mortar, Rocket Launchers and Artillery shells with proximity fuzes which generate a rapid release of energy in the form of shock waves. The release of high energy and the developed shock waves are associated with significant structural and collateral damage. Considering the vulnerability when the structures are subjected to such intense loadings, an experimental and numerical study has been carried out to investigate the damage resistance of reinforced concrete (RC) slabs against blast loading. The target slabs (1000 mm × 1000 mm × 100 mm) have been subjected to blast developed by three different weights of explosive equivalent to the quantity of explosive commonly used by terrorists and military in mortars, high explosive shells of rocket launcher and artillery shells with proximity fuzes. The explosive has been detonated from two different standoff distances corresponding to the scaled distance 0.079–0.527 m/kg1/3. The different failure modes and levels of blast-induced damage enabled better understanding of the performance of RC slabs when subjected to a similar impact/shock by mortars and rocket launchers. The one-way bending of the slab becomes more dominant with an increase in the explosive charge. On the other hand, the localized failure of the slab transformed into a globalized deformation with the increase in the standoff distance. The finite element simulations performed in ABAQUS/Explicit reproduced the damage, formation of the crater and spalling/scabbing of concrete. The blast pressure increased with an increase in the amount of TNT while reduced with the increase in the standoff distance.

Research and Design of proximity fuze Scheme Based on 24GHz Radar Sensor

Modern warfare requires more and more adaptability to the environment. The proximity fuze based on microwave radar sensor has high anti-interference performance, which can achieve accurate hit and high efficiency damage in the complex environment. The microwave radar sensor has the characteristics of strong anti-interference ability, high precision of ranging and high speed measurement, and can accurately extract target information. This paper mainly introduces a design and implementation scheme of proximity fuze based on 24GHz microwave radar. With a small spatial structure and high integration, combined with the Doppler principle, antenna scanning technology and FFT system software design, the detonation range of the lowest 0.5m and 30m is determined effectively and reliably with a low false alarm probability.

Laser echo characteristics and detection probability calculation on the space projectile proximity fuze

This paper presents a new calculation method for characterization of the laser echo under the space confrontation of the projectile and damaged target. We improve the damage efficacies of the projectile fuze through searching the effective proximity probability and model of the projectile fuze, and then utilize the coordinate converted relationship between the projectile and the damaged target to establish the calculation function of the power of the laser echo by the laser echo waveform. Next, the spatial coordinate transformation relation of the projectile and the damaged target will be provided, and investigate the effective proximity probability calculation method of the projectile fuze when the projectile flying direction and the damaged target is random in the space intersection status. Moreover, the calculation function of the power of the laser echo under multiple space intersection and the calculation function of the minimum detectable optical power provides the new calculation function of the detection probability under different space intersections. The results of the calculation and experimental investigation show that different space intersections of the projectile flying direction and the damaged target and the detection distance affect the power of the laser echo. In addition, we show that, increasing the projectile velocity will enhance the power of the laser echo, and results in a higher the detection probability.

Research on the burst height measurement method based on the missile-borne millimeter wave detector

A millimeter wave detector is applied to a novel large dynamic optional burst height proximity fuze, and it provides a higher measurement precision. In this paper, the height measurement model of the missile-borne millimeter wave detector is established to provide a theoretical basis for the measurement of burst height. A burst height measurement method based on the change rate of voltage and Doppler shift has been proposed. Compared with the traditional millimeter wave fuze continuous wave height measurement system, the proposed method shows higher measurement accuracy and faster computing speed. Through a series of digital simulation experiments, the proposed method allows the height to be estimated when the terrain reflectivity is unknown.

Analysis and design of proximity fuze based on waveguide discontinuity

In order to satisfy the special requirement of antenna directivity base on proximity Fuze, the concept of the waveguide discontinuity was introduced which could be a method of designing antenna. The beam of radiation should deviate from axis direction of bomb in a certain angle The frequency was between 24 GHz and 25 GHz.Circular waveguide was connected to coaxial waveguide. This form could inspire high model in discontinuity place. Electric field of coupling model could lead to a oblique radiation pattern. In the meanwhile, two symmetrical metal column was loaded in waveguide in purpose of changing impedance of antenna. The test results demonstrated the veracity of the analysis.

지상 접근 표적 감지를 위한 초소형 K-대역 레이다 연구

This paper proposes a compact K-band radar applied to a miniature proximity fuze for the active defense system. In this terrestrial environment, it is not easy to detect approaching small targets because the clutter is scattered. In addition, it is difficult to miniaturize the radar for the small proximity fuze while improving the target accuracy of the radar in such environments. To solve these difficulties, this study presents system analysis and design, antenna design, and transceiver and signal processor design of the compact K-band radar. Some test results are presented and the results are analyzed, the validity of the proposed study is examined.

Miniaturization and Bandwidth Enhancement of a Microstrip Patch Antenna Using Magneto-Dielectric Materials for Proximity Fuze Application

The exact calculation of height of burst has always been a challenge in the design of proximity fuzes. Radio frequency-based sensors can be designed for this purpose but the size and bandwidth of the antenna increases the design complexity; hence, miniaturization of the patch antenna using barium hexaferrite (BaFe12O19) as substrate material is proposed in this paper. The nanohexaferrite substrate material was prepared using a wet chemical method and characterized for structural and electromagnetic properties. An average crystallite size of 60 nm was obtained from x-ray diffraction. Scanning electron microscopy and transmission electron microscopy also confirms the formation of homogenous nanoferrites. Complex permittivity (ɛ* = 6.2 − 0.04 j) and complex permeability (μ* = 1.9 − 0.18 j) were obtained from electromagnetic characterization. The antenna structure fabricated and simulated confirms that, with the obtained electromagnetic parameters of synthesized magneto-dielectric material, the size of antenna can be reduced up to 42.5%. It also increases the bandwidth from 68 MHz to 166 MHz with respect to antenna on FR4 substrate. Therefore, BaFe12O19 is proposed as a suitable candidate for a high-bandwidth, miniaturized antenna for proximity fuzes.

Research on the characteristics of fog backscattering signals for frequency modulated continuous wave laser fuze

Fog backscattering is one of the major reasons for false alarming in the laser proximity fuze. However, its influence to the frequency modulated continuous wave (FMCW) laser fuze has not been well studied. In this paper, a Monte-Carlo simulation model of the FMCW laser transmission in fog based on the laser detection principle and the Mie scattering theory was established. The simulation results showed that the fog backscattering signals spread the beat signals spectrum. Experiments were also performed in a simulated laboratory environment and the results confirmed the findings. Therefore, this study can greatly assist the signal identification between target reflection and fog backscattering and potentially avoid the false alarms.

Effect of plane target characteristics on ranging distribution for pulse laser detection

Laser proximity fuze is a kind of active detecting system which has been extensively equipped in both conventional and guided missile ammunitions. It uses a pulsed laser for detecting and ranging a target, accurately providing information about target angle and distance. The system emits a short pulse of laser beams which come into contact with the target and receives the light scattered back. After transducing light into electric signal, target range could be obtained with proper signal processing technique. The width and amplitude of the echo could vary if targets are of different characteristics, which leads to distributed target ranging results. Therefore, a better understanding of the relationship between target characteristic and ranging distribution can increase the precision of the pulsed laser proximity detecting system.In this paper, the emitted laser is modeled as a Gaussian pulse. The corresponding impulse response equation and echo equation of the pulsed laser for the planer target are derived. Considering the echo broadening effect, relative broadening ratio is determined from the echo equation. Then the relationships between the echo broadening coefficient and the parameters of tilt angle of planar target, laser divergence angle, and laser pulse width are analyzed. The results show that relative broadening ratio increases with the increase of the tilt angle of planar target or laser divergence angle, and decreases as the laser pulse width decreases. Based on the echo equation of pulsed laser and constant threshold leading edge detection, the probability density function of the planar target ranging is derived analytically. The influences of changing parameters of tilt angle of planar target, power of emitted laser, laser divergence angle, and threshold-to-noise ratio（TNR) on statistical ranging distribution are simulated.Monte Carlo simulation is performed for the whole waveform ranging experiment. The pulsed laser ranging platform is built and 20 m ranging experiment is conducted. The result shows that the ranging probability density distribution from Monte Carlo simulation is close to that from the experiment. As the tilting angle of target increases, ranging mean and variance both increase. When the tilting angles are 0, 20, 40 or 60, the signal-to-noise ratio（SNR) is larger than the TNR, and the ranging distribution is Gaussian. When the tilting angle is 70, the SNR is smaller than the TNR, and the ranging distribution is distorted with a longer rising edge and a shorter falling edge from the original Gaussian profile. This study could provide theoretical basis for the research of the ranging distribution of pulsed laser detector with the consideration of target characteristic.

Recent Advancements in Proximity Fuzes Technology

Recent Advancements in Proximity Fuzes Technology

Study on Capacitance Proximity Fuze Burst Height Dispersion

Based that the capacitance proximity fuze detection field is quasi-electrostatic, the field intensity distribution function is formed on the analogy of radio fuze. By simulating a conclusion is drawn that its equifield intensity detection directional diagram is nearly an ellipsoid, whose long axis is 20% longer than the minor one. The study validates the capacitance proximity fuze burst height disperses uniformly while the missile and target intersect differently.

Design of Low-Noise Receiving Amplifier Circuit for Laser Proximity Fuze

In order to improve the detection distance of laser proximity fuze without increasing laser power, the capability of laser fuze receiving weak laser echo signal must be improved. An avalanche photodiode (APD), which had the advantages of high sensitivity, low noise, with inner gain, was used as photodetector in laser fuze system to improve the capability of laser fuze detecting weak signal. The equivalent noise model of APD photoelectric conversion was analyzed, and the low-noise preamplifier and voltage amplification circuit matching the avalanche photodiode were designed. The noise ratio and frequency bandwidth of amplification circuit were analyzed and calculated, also the simulation and experimental verification were accomplished. The results showed that the circuit has wide bandwidth and high signal to noise ratio,which meets the requirements of subsequent processing circuitry of laser fuze.

Optical and Electro-Optical Instrumentation

Importance of Optical and Electro-Optical Instrumentation is growing by leaps and bounds in the modern day battlefield. Night vision devices both image intensifier (II) Tube based and thermal imagers (TIs) are true force multipliers as they allow weapons and equipments to be used during day and night in fair and bad weather conditions. Growing trends in the thermal imaging area are mega pixels arrays with smaller pixel size, active and passive imaging at the focal plane, new detector materials operating at elevated temperature, dual color detectors, advanced signal and image processing, sensor and image fusion and automatic target recognition capability. With sufficient exploitations of these devices on ground, worldwide focus is towards the militarization of space by deploying multi / hyper spectral imagers for better target discrimination. Low power non-lethal laser instrumentation is also emerging as another key area to fight a battle taking the shapes of Laser range finders, gap measuring devices, precision guided munitions, and laser proximity fuzes. The key trends in laser instrumentation area are eye-safe lasers, laser diodes arrays, diode pumped laser designators, high power lasers with adaptive beam-shaping, sensor fuzed seekers and 3-D laser imaging. Defence Science Journal, 2013, 63(6), pp.543-544, DOI:http://dx.doi.org/10.14429/dsj. 63.5746

방향 탐지용 전파형 대공 근접 신관센서

This paper presents the direction finding proximity fuze sensor using the clutter rejection method and the adaptive target detection algorithm for anti-air missiles. To remove effects by clutter and detect a target accurately, the clutter rejection method of Legendre sequence with BPSK(Bi phase Shift Keying) modulation has been proposed and the Doppler signal which has cross correlation characteristics is obtained from reflected target signals. Considering the change of the Doppler signal, the adaptive target detection algorithm has been developed and the direction finding algorithm has been fulfilled by comparing received powers from adjacent three receiving antennas. The encounter simulation test apparatus was made to collect and analyze reflected signal and test results showed that the -10 dBsm target was detected over 10 meters and the target with mesh clutter was detected and direction was distinguished definitely.Keywords : BPSK, Cross-Correlation(교차상관), Range Gate(거리 창), Clutter Rejection(클러터 제거), Direction Finding Fuze(방향구분 신관)