• 한국군사과학기술학회지
• /
• 제2권2호
• /
• pp.30-39
• /
• 1999

In this paper, we have proposed a novel method which can compose a reflected signal of the underwater target. The synthesis of the reflected signal in the target, the synthesized signal being similar to the characteristics of the reflected signal in the real target, is used the highlight model at the specific points of the target. We suggest the synthesis method of the reflected signal of the target using the pulsewidth variation and each other doppler effect at the highlight point, and compare the composed signal by the proposed method with that by conventional one. Simulation results show that the composed signal using the proposed method and the reflected signal of the real target is similar to the spectral characteristics.

• 한국군사과학기술학회지
• /
• 제26권3호
• /
• pp.246-251
• /
• 2023

RADAR(Radio Detection and Ranging) is an important system for surveillance and reconnaissance by detecting a reflected signal which obtains the range from the radar to the target, and the velocity of the target. The magnitude of the reflected signal varies due to the radar cross section of the target, characteristic of the transmission and reception antenna, distance between the radar and the target, and power and wavelength of the transmitted signal. Thus, the RCS is the important characteristic of the target to determine if the target can be observed by the RADAR system. It is based on the material and shape of the target. We have measured the reflection signal of a simple square-shaped (20 × 20 cm) target made of a new material, a gallium-based liquid metal alloy and compared that of well-known metals including copper, aluminum. The magnitude of reflected signal of the aluminum target was the largest and it was 2.4 times larger than that of the liquid metal target. We also investigated the effect of the shape by measuring reflectance of the F-22 3D model(~1/95 ratio) target covered with/without copper, aluminium, and liquid metal. The largest magnitude of the reflected signal measured from side-view with the copper-covered F-22 model was 2.6 times greater than that of liquid metal. The reflectance study of the liquid metal would be helpful for liquid metal-based frequency selective surface or metamaterials.

• 한국멀티미디어학회논문지
• /
• 제20권10호
• /
• pp.1637-1645
• /
• 2017

Target/Nontarget classification can be divided into the study of shape estimation of the target analysing reflected echo signal and of type classification of the target using acoustical features. In active sonar system, the feature vectors are extracted from the signal reflected from the target, and an classification algorithm is applied to determine whether the received signal is a target or not. However, received sonar signals can be distorted in the underwater environments, and the spatio-temporal characteristics of active sonar signals change according to the aspect of the target. In addition, it is very difficult to collect real sea-trial data for research. In this paper, target/non-target classification were performed using real sea-trial data. Feature vectors are extracted using MFCC(Mel-Frequency Cepstral Coefficients), filterbank energy in the Fourier spectrum and wavelet domain. For the performance verification, classification experiments were performed using backpropagation neural network classifiers.

• 대한임베디드공학회논문지
• /
• 제12권1호
• /
• pp.27-34
• /
• 2017

The signal transmitted from radar is not reflected from a single point when the signal reflected by complex target. Resultantly, the amplitude and phase of the received signal can be changed because the target has lots of scatterers. The changes of the amplitude and the phase mean Glint and RCS, respectively. Although the Glint and RCS that caused by the same scatters are uncorrelated, however, they are not independent completely. Therefore, this paper proposes a method for generating the Glint and RCS by using same random number generator. And the time correlations of the Glint and RCS are respectively implemented in frequency domain by using each power spectral density of them.

• 한국군사과학기술학회지
• /
• 제16권5호
• /
• pp.613-621
• /
• 2013

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.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2001년도 ICCAS
• /
• pp.158.2-158
• /
• 2001

This paper introduces the design and implementation of a signal processing system for an airborne active homing radar system. This airborne active homing radar system uses the pulse Doppler radar of high PRF (Pulse Repetition Frequency) for computation of exact relative velocity of the target. This system carries out two operations mainly. The first is to transmit and receive microwave signal through the antenna. The second is to calculate the relative velocity of the target taking advantage of the Doppler frequency signal reflected from the target and detect the angle error between a target and an antenna LOS (Line Of Sight) to make the antenna direction coincident with the target. The signal processing system has a role of the latter.

• 한국전자통신학회논문지
• /
• 제15권5호
• /
• pp.813-818
• /
• 2020

본 연구는 초단파 대역에서의 표적 반사 신호 특성 및 분석에 대한 연구이다. 사전에 목표물에 대한 RCS 특성을 CST 전자기 해석툴을 사용하여 분석하고 Bi-Static 방법으로 목표물을 탐지하여 신호대 잡음비의 변화에 대해서 시험하였다. 시험결과는 사전 입사각도에 따른 RCS 분석에 대한 결과와 같이 목표물에 반사되는 신호 탐지에 대한 신호대 잡음비 특성이 큰 변동이 없는 유사한 결과를 보여준다. 향후 본 연구를 통하여 X 대역에 비하여 파장이 상대적으로 큰 VHF/UHF 대역 레이다의 표적에 대한 RCS 분석 및 등의 표적 탐지에 대한 특성 기술에 활용할 예정이다.

• 한국시뮬레이션학회논문지
• /
• 제9권3호
• /
• pp.1-11
• /
• 2000

This paper proposes the practical echo-signal synthesis models - UTAHID (Underwater TArget by Highlight Distribution) & M-UTAHID(Modified UTAHID) - of underwater target for active sonar engineering At high frequencies all the echo components that are the specular reflected waves and various elastic scattering wave scan be regarded the summation of individual echo from some equivalent scattering centers, so the underwater target is characterized by highlights distributed in spatial target structure. Proposed models are compared with characteristics of random distributed model & equivalent interval highlight model, and analyzed target strength, echo-elongation effect, target time spread loss and so on. Thus these can be efficiently used in various real systems related to underwater target echo-signal synthesis on active sonar and acoustic countermeasure.

• 전기전자학회논문지
• /
• 제24권4호
• /
• pp.1034-1038
• /
• 2020

레이더를 통한 표적식별을 효과적으로 처리하기 위해서는 표적에 대한 정확한 신호 정보가 필요하다. 그러나 이러한 표적 신호에는 잡음이 섞여 있는 경우가 일반적이며, 이 부분에 대한 연구가 지속적으로 이루어지고 있다. 특히 표적에 대한 이미지 처리, 표적신호처리, 표적식별 등이 그 예라 할 수 있겠다. 군사적 측면으로 볼 때 표적식별 분야가 중요하므로 본 논문에서는 트리 구조의 퍼지 뉴럴 네트워크를 이용하여 비행체 표적식별에 대한 연구를 수행하였다. 비행체에 대한 반사파 데이터를 활용하여 퍼지 뉴럴 네트워크를 학습시켜 모델에 대한 최적화를 수행하였고, 최적화된 모델에 표적에 대한 테스팅 데이터를 입력하여 표적식별에 대한 실험을 수행하여 그 결과를 통해 제안된 방법의 효용성을 검증하였다.

• 한국군사과학기술학회지
• /
• 제4권1호
• /
• pp.93-103
• /
• 2001

고주파를 주로 사용하는 능동소나에서 반사신호는 물체표면의 거울면 반사와 내부의 여러 등가적인 산란자로 형성되며, 이는 물체에 공간적으로 분포된 하이라이트에 의해 특징 된다. 본 연구에서는 기존의 모의표적에 대한 반사신호 합성모델 즉, 랜덤분포 모델, 등간격분포 모델 및 MUTAHID 모델에 대하여 분석하고, 합성된 반사신호 결과특성을 여러 조건에서 비교하였다. 이러한 하이라이트 분포 모델들은 수중표적의 반사신호 합성을 필요로 하는 각종 실시스템의 모의표적 신호 합성에 유용하게 적용될 수 있으리라 생각된다.