바이스태틱 레이더에서 Range Walk이 보상된 Squint Cross-Range 도플러 프로세싱

윤재혁(Jae-Hyuk Youn),김관수(Kwan-Soo Kim),양훈기(Hoon-Gee Yang),정용식(Yong-Seek Chung),이원우(Won-Woo Lee),배경빈(Kyung-Bin Bae) 한국전자파학회 2011 한국전자파학회논문지 Vol.22 No.11

고속의 이동 표적을 탐지하는 경우, 특히 송수신부가 독립적으로 이동하는 바이스태틱 레이더의 경우 표적 신호의 레인지 워크(range walk)는 도플러 프로세싱(Doppler processing) 및 표적 탐지를 어렵게 한다. 본 논문에서는 표적 신호에 레인지 워크가 있는 경우 우선 레인지(range) 방향 인터폴레이션(interpolation)을 수행해서 일정한 시간간격으로 샘플링된 표적 성분이 있는 레인지 빈(range bin)을 추출하고, 이어서 도플러 프로세싱을 통한 도플러 정보 추출 알고리즘을 제시한다. 이를 위해 바이스태틱 레이더 환경을 가정하고, 펄스 압축에 의해 레인지 프로세싱 과정을 포함한 도플러 프로세싱 과정을 이론적으로 설명한 후 시뮬레이션을 통하여 제시된 방식의 타당성을 보인다. Range walk has been a major problem in achieving correct Doppler processing. This frequently occurs when range variation is severe just like in a bistatic radar or in high speed target scenario. This paper presents a range walk compensated range-Doppler processing algorithm applicable to the bistatic radar. In order for the compensation, a range-domain interpolation is applied for range compressed signal so that Doppler processing is performed along the evenly time-spaced range bins that contain target returns. Under a bistatic radar scenario, the proposed algorithm including a range domain pulse compression is mathematically described. Finally, the validity of the algorithm is demonstrated by simulation results showing the superiority of a SCDP(Squint Cross-range Doppler Processing) over an uncompensated Doppler processing.

부 대역을 이용한 수중 음향 통신 송수신 구조 및 실험 결과 분석

정현우(Hyun-Woo Jeong),신지은(Ji-Eun Shin),정지원(Ji-Won Jung) 한국정보전자통신기술학회 2020 한국정보전자통신기술학회논문지 Vol.13 No.6

본 논문에서는 부 대역 처리를 이용하는 수중 통신에서 은밀성과 성능 향상 관점에서 효율적인 송수신 구조를 제시하였다. 은밀성적인 측면에서는 암호화된 부호화 비트를 블록으로 나누어 각 비트의 정보를 이용하여 중심 주파수와 부 대역을 결정하므로 은밀성을 유지하는 측면에서 효과적이다. 수중 통신에서 성능적인 측면에서는 다중 경로 특성, 도플러 확산, 프레임 동기 등이 성능에 영향을 미치는 결정적인 요소이다. 따라서 본 논문에서는 이러한 요소들을 극복하기 위해, 비동기 에너지 검출 방식과 터보 등화 기법, 그리고 최적의 프레임 동기 방식을 제안하여 수신부에 적용하였다. 호수 실험에서 최적의 프레임 동기 방식을 수신부에 적용한 결과 다섯 개의 프레임 중에서 네 개의 프레임에서 오류를 모두 정정함을 확인하였다. This paper presented efficient transceiver structure using sub-band processing for underwater communication in terms of covertness and performance improvement. In aspect of covertness, encrypted coded-bits are divided into groups, and center frequency and sub band are determined by coded-bits of each group. Therefore, as center frequencies are changed randomly, it maintain the covertness effectively. In aspect of performance improvement, the performance of underwater communication mainly depends on multi-path propagation characteristics, Doppler-spread, and frame synchronization. Accordingly, in order to overcome these effects, non-coherent energy detector and turbo equalization method are employed in receiver side. Furthermore, optimal frame synchronization was proposed. Through the simulation and lake experiment, performance analysis was conducted. Especially in the lake experiment, as a result of applying optimal frame synchronization method to receiver structure, errors are corrected in most frames.

복잡한 클러터 환경에서 펄스도플러 레이더 추적필터를 위한 파티클 필터 연구

권지훈(Ji Hoon Kwon),하성재(Sung Jae Ha) 산업기술교육훈련학회 2018 산업기술연구논문지 (JITR) Vol.23 No.3

This paper reports on the effectiveness of a particle filter for a pulsed Doppler radar in a heavy clutter environment. For this purpose, we designed a pulsed Doppler radar simulator for tracking a virtual target. This simulator encompasses the whole procedure of radar signal processing. In order to consider the non-linearity of the measurement data and a heavy clutter environment, we lowered the constant false alarm rate threshold level to generate many false alarms and we considered a moving target following a complex path. Under these conditions, the tracking performances of an extended Kalman filter (EKF) and the particle filter were analyzed and compared. The results show that the performance of the particle filter was more reliable than that of the EKF in the given scenario.

Use of Wigner-Ville transformations for fluid particles in laser Doppler flow accelerometry

전세종,권휴상 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.3

Flow acceleration with Lagrangian description is crucial to understanding particle movements in turbulent jet flows or dissipation statistics in isotropic turbulence. Laser Doppler anemometry is regarded as a suitable experimental tool for measuring flow acceleration,because scattering particles generate trajectories in the measurement volume, which process gives rise to flow acceleration at a fixed measuring point with the Lagrangian description. The most useful algorithm for processing Doppler signals is either the quadrature demodulation technique (QDT) or the iterative parametric method (alternatively, the minimization of least squares, LSM) as in the literature. In the present study, another algorithm using the Wigner-Ville transform (W-V) is introduced to give more accurate estimation of flow acceleration than the QDT or the LSM. Five signal-processing algorithms, including the QDT, the LSM, the MC (maximization of correlation),and the W-V, were compared with each other in experiments with an impinging air jet flow with a cylindrical rod and a round free-air jet flow. Mean flow acceleration distribution in the streamwise direction was mainly investigated. Processing speeds for the above-mentioned signal-processing algorithms were checked to find the best algorithm, which has best performance with short processing time. Although QDT was found to be an accurate algorithm with short processing time, it has limited applications to flows with large acceleration and high SNR. The MC was also found to be a good algorithm with moderate processing speed, which can be useful in flows with low SNR because the MC is an iterative parametric method. The W-V gave the most accurate values for flow acceleration;however, the processing time for this method was the slowest among the signal-processing algorithms.

LD의 자기혼합 효과를 이용한 LDF의 신호처리 알고리즘의 평가

고한우,김종원,Go, Han-U,Kim, Jong-Won 대한의용생체공학회 1998 의공학회지 Vol.19 No.4

본 논문에서는 레이저 다이오드의 자기혼합 효과를 이용한 레이저 도플러 혈류계를 위한 신호처리 알고리즘들에 대한 in vitro적인 실험결과를 비교하였다. 단순하고 유연성있는 레이저 도플러 시스템을 구성함으로써 디지털 신호해석 방법에 의하여 여러 가지 신호처리 알고리즘들을 비교할 수 있도록 하였다. 이 시스템은 다양한 알고리즘을 퍼스널 컴퓨터를 사용하여 소프트웨어로 제어하므로써 다양한 알고리즘을 선택하여 비교 연구할 수 있도록 하였다. 또한, 유체 흐름의 재현성과 조직의 혈류 흐름을 모의하기 위하여 두 개의 실험적인 혈류모델을 제작하여 적용하였다. 광원은 파장 780nm의 레이저 다이오드를 사용하였으며, 3 종류의 입자 농도와 속도를 갖는 액체를 두 개의 실험모델에 흘리면서 측정된 결과들을 비교하였다. 그 결과 주파수로 가중되지 않은 알고리즘(0차 모멘트)이 속도와 농도변화를 잘 나타내는 반면에 주파수로 가중된 알고리즘들(1차와 2차 모멘트, 0차 모멘트와의 비)은 농도보다는 속도 변화를 잘 나타내었다. This paper describes the results of investigations comparing the relative in vitro responses of different signal processing algorithms for laser Doppler flowmetry(LDF) using self-mixing effect of laser diode(LD). A versatile laser Doppler system is described which enabled complex signal processing to be implemented relatively simply using digital analysis. The flexibility of the system allowed a variety of processing algorithms to be studied by simply characterising the algorithm of interest under software control using a personal computer. Two in-vitro physical models are also presented which was used to maintain reproducible fluid flows Flows of particles were studied in two physical models using a 780nm laser diode source. The results show that frequency weighted algorithms(first and second moments, rate to zero moment) are responsive to particle velocity more than concentration, whereas non-weighted algorithm (zero moment responds to concentration and velocity.

도플러 레이더를 이용한 포구속도 계측 시 클러터 제거 방법

김형래 한국항행학회 2019 韓國航行學會論文誌 Vol.23 No.2

포구속도는 총포탄약의 평가에 있어 가장 중요한 계측항목들 중 하나이다. 포구속도는 포탄이 포구를 떠나는 시점의 속도로 정의된다. 특히, 포구속도는 추진제의 성능과 밀접하게 관련이 있기 때문에 정확한 측정이 요구된다. 포구속도의 측정에는 도플러 레이더가 사용되나, 도플러 레이더 신호의 품질은 시험장 환경에 의존한다. 따라서 본 논문에서는 도플러 레이더의 신호 품질을 악화시키는 클러터를 시험장 구조 및 신호처리 방법의 개선을 통해 제거하는 방법을 제시하였다. 개선된 신호처리 방법의 적용을 위해 도플러 레이더의 원시 도플러 데이터를 획득하는 프로그램을 작성하였다. 시험장 구조 및 신호처리 방법의 개선을 통해 얻어진 속도 데이터에 대한 통계적인 검증으로 제안하는 방법이 기존에 사용하던 방법에 비해 클러터 제거에 효과가 있음을 증명하였다. Muzzle Velocity is one of the most important measurement items for evaluation of ammunition. The muzzle velocity is defined as the velocity when the projectile leaves the muzzle. Particularly, since the muzzle velocity is closely related to the performance of the propellant, precise measurement of muzzle velocity is required. Doppler radar is used to measure the muzzle velocity, but the quality of Doppler radar signal depends on the test site environment. In this paper, a method to remove the clutter that degrades the signal quality of Doppler radar by improving the structure of the test site and the signal processing method is suggested. For the application of the improved signal processing method, a program for acquiring Doppler radar 's raw Doppler data was created. Statistical verification of the velocity data obtained through the improvement of the test site structure and signal processing method proved that the proposed method is effective for the removal of clutter as compared with the existing method.

Drone Detection with Chirp‐Pulse Radar Based on Target Fluctuation Models

김병관,박준형,박성진,김태완,정대환,김도훈,박성욱,김태형 한국전자통신연구원 2018 ETRI Journal Vol.40 No.2

This paper presents a pulse radar system to detect drones based on a target fluctuation model, specifically the Swerling target model. Because drones are small atypical objects and are mainly composed of non‐conducting materials, their radar cross‐section value is low and fluctuating. Therefore, determining the target fluctuation model and applying a proper integration method are important. The proposed system is herein experimentally verified and the results are discussed. A prototype design of the pulse radar system is based on radar equations. It adopts three different pulse modes and a coherent pulse integration to ensure a high signal‐to‐noise ratio. Outdoor measurements are performed with a prototype radar system to detect Doppler frequencies from both the drone frame and blades. The results indicate that the drone frame and blades are detected within an instrumental maximum range. Additionally, the results show that the drone's frame and blades are close to the Swerling 3 and 4 target models, respectively. By the analysis of the Swerling target models, proper integration methods for detecting drones are verified and can thus contribute to increasing in detectability.

도플러 레이더 패턴 인식을 통한 인간 보행 감지 및 배경잡음 제거 기법

권지훈(Jihoon Kwon),곽노준(Nojun Kwak) 한국자동차공학회 2016 한국자동차공학회 부문종합 학술대회 Vol.2016 No.5

In the conventional radar system, a threshold level is adjusted by the received noise level for maintaining detection and false alarm performances. However, when high level noise is received, a threshold level also increases and detection range can be reduced. In this paper, we will present a new method of pedestrian detection and background noise classification using Doppler radar pattern recognition technique without using a threshold level. We apply the multilayer perceptron to classify the human normal walking motion from the background noise. The estimation accuracy for the background noise and human normal walking motion are about 97.9% and 90.1% individually. This result shows that the pattern recognition approach can be the effective method to remove the background noise for pedestrian detection.

GPS 미약신호 처리 알고리즘

우제르(Uzair Ahmad),최완식(Choi Wan Sik) 한국항해항만학회 2011 한국항해항만학회 학술대회논문집 Vol.2011 No.춘계

This paper concerns to the acquisition of Global Positioning System L1 C/A coded signals. It specifically addresses the issues of acquiring very low power signals which are attenuated due to special circumstances such as indoor environment or forest canopy etc. The proposed post-processing algorithm applies modified signal folding coherent integration scheme on weak signal record. It dynamically compensates the doppler effect on the length of C/A code before integrating the signal power. Experimental results show effectiveness of the algorithm on weak GPS signals recorded in a real environment.

도플러 저해상도 레이다의 탐지성능 향상을 위한 속도 기반 하이브리드 도플러 처리 기법

권대현(Daihyun Kwon),조병래(Byung-Lae Cho),윤기철(Kichul Yoon),김관성(Kwan Sung Kim),김찬홍(Chan-Hong Kim) 한국정보기술학회 2023 한국정보기술학회논문지 Vol.21 No.2

In this paper, the velocity based hybrid doppler processing method is proposed to increase SIR. The proposed method uses two filters, MTI and FIR, for each velocity interval. The proposed algorithm uses a velocity boundary and two parameters are specified by Monte Carlo simulation that determine this value. The first is the ambiguity velocity which has a linear relationship with the velocity boundary. The second is the standard deviation of the FIR filter, and we investigate that it is logarithmic with the velocity boundary. Since the detection probability increases as the SIR increases, the detection performance improves as the SIR increases. Finally, the proposed algorithm was verified through simulation.