• Title/Summary/Keyword: TDOA Method

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A Sequential Estimation Algorithm for TDOA/FDOA Extraction for VHF Communication Signals (VHF 대역 통신 신호에서 TDOA/FDOA 정보 추출을 위한 순차 추정 알고리즘)

  • Kim, Dong-Gyu;Kim, Yong-Hee;Park, Jin-Oh;Lee, Moon Seok;Park, Young-Mi;Kim, Hyoung-Nam
    • Journal of the Institute of Electronics and Information Engineers
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    • v.51 no.7
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    • pp.60-68
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    • 2014
  • In modern electronic warfare systems, a demand on the more accurate estimation method based on TDOA and FDOA has been increased. TDOA/FDOA localization consists of two-stage procedures; the extraction of information from signals, and the estimation of emitter location. CAF(complex ambiguity function) is known as a basic method in the extraction stage. However, when we extract TDOA and FDOA information from VHF(very high frequency) communication signals, conventional CAF algorithms may not work within a permitted time because of much computation. Therefore, in this paper, an improved sequential estimation algorithm based on CAF is proposed for effective calculation of extracting TDOA and FDOA estimates in terms of computational complexity. The proposed method is compared with the conventional CAF-based algorithms through simulation. In addition, we derive the optimal performance based on the CRLB(Cramer-Lao lower bound) to check the extraction performance of the proposed method.

A 2-Step Global Optimization Algorithm for TDOA/FDOA of Communication Signals (통신 신호에서 TDOA/FDOA 정보 추출을 위한 2-단계 전역 최적화 알고리즘)

  • Kim, Dong-Gyu;Park, Jin-Oh;Lee, Moon Seok;Park, Young-Mi;Kim, Hyoung-Nam
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.4
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    • pp.37-45
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    • 2015
  • In modern electronic warfare systems, a demand on the more accurate estimation method based on TDOA and FDOA has been increased. TDOA/FDOA localization consists of two-stage procedures: the extraction of information from signals and the estimation of emitter location. Various algorithms based on CAF(complex ambiguity function), which is known as a basic method, has been presented in the area of extractions. When we extract TDOA and FDOA information using a conventional method based on the CAF algorithm from communication signals, considerably long integration time is required for the accurate position estimation of an unknown emitter far from sensors more than 300 km. Such long integration time yields huge amount of transmission data from sensors to a central processing unit, resulting in heavy computiational complexity. Therefore, we theoretically analyze the integration time for TDOA/FDOA information using CRLB and propose a two-stage global optimization algorithm which can minimize the transmission time and a computational complexity. The proposed method is compared with the conventional CAF-based algorithms in terms of a computational complexity and the CRLB to verify the estimation performance.

TDOA Measurement Based Taylor Series Design Method Considering Height Error for Real-Time Locating Systems (실시간 위치추적 시스템에서 높이 오차를 고려한 TDOA 측정치 기반 테일러 급수 설계 방법)

  • Kang, Hee-Won;Hwang, Dong-Hwan;Park, Chan-Sik
    • Journal of Institute of Control, Robotics and Systems
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    • v.16 no.8
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    • pp.804-809
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    • 2010
  • This paper proposes a Taylor-series design method which reduces the height error of the tag when readers are arranged at the same height in 3-dimensional space. The proposed method consists of two steps. Firstly, the planar position is estimated by the Taylor-series method using the TDOA measurement. Next, the height is estimated from the estimated planar position. In order to show the validity of the proposed method, computer simulations were performed for the static case and linear trajectory of the tag. Results show that the proposed method gives convergent estimated position and better height estimate than the Taylor series method.

Comparisons of Error Characteristics between TOA and TDOA Positioning in Dense Multipath Environment (다중경로 환경에서의 TOA방식과 TDOA방식의 측위성능 비교)

  • Park, Ji-Won;Park, Ji-Hee;Song, Seung-Hun;Sung, Tae-Kyung
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.2
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    • pp.415-421
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    • 2009
  • TOA(time-of-arrival) and TDOA(time-difference-of-arrival) positioning techniques are commonly used in many radio-navigation systems. From the literature, it is known that the position estimate and error covariance matrix of TDOA obtained by GN(Gauss-Newton) method is exactly the same as that of TOA when the error source of the range measurement is only an IID white Gaussian noise. In case of geo-location and indoor positioning, however, multi-path or NLOS(non-line-of-sight) error is frequently appeared in range measurements. Though its occurrence is random, the multipath acts like a bias for a stationary user if it occurs. This paper presents the comparisons of error characteristics between TOA and TDOA positioning in presence of multi-path or NLOS error. It is analytically shown that the position estimate of TDOA is exactly the same as that of TOA even when bias errors are included in range measurements with different magnitudes. By computer simulation, position estimation error and error distribution are analyzed in presence of range bias errors.

A study on the sequential algorithm for simultaneous estimation of TDOA and FDOA (TDOA/FDOA 동시 추정을 위한 순차적 알고리즘에 관한 연구)

  • 김창성;김중규
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.35S no.7
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    • pp.72-85
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    • 1998
  • In this paper, we propose a new method that sequentially estimates TDOA(Time Delay Of Arrival) and FDOA(Frequency Delay Of Arrival) for extracting the information about the bearing and relative velocity of a target in passive radar or sonar arrays. The objective is to efficiently estimate the TDOA and FDOA between two sensor signal measurements, corrupted by correlated Gaussian noise sources in an unknown way. The proposed method utilizes the one dimensional slice function of the third order cumulants between the two sensor measurements, by which the effect of correlated Gaussian measurement noises can be significantly suppressed for the estimation of TDOA. Because the proposed sequential algoritjhm uses the one dimensional complex ambiguity function based on the TDOA estimate from the first step, the amount of computations needed for accurate estimationof FDOA can be dramatically reduced, especially for the cases where high frequency resolution is required. It is demonstrated that the proposed algorithm outperforms existing TDOA/FDOA estimation algorithms based on the ML(maximum likelihood) criterionandthe complex ambiguity function of the third order cumulant as well, in the MSE(mean squared error) sense and computational burden. Various numerical resutls on the detection probability, MSE and the floatingpoint computational burden are presented via Monte-Carlo simulations for different types of noises, different lengths of data, and different signal-to-noise ratios.

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Precision Time Synchronization System over Wireless Networks for TDOA-based Real Time Locating Systems (TDOA 기반의 실시간 위치 측정 시스템을 위한 정밀 무선 시각 동기 시스템)

  • Cho, Hyun-Tae;Jung, Yeon-Su;Jang, Hyun-Sung;Park, In-Gu;Baek, Yun-Ju
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.1B
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    • pp.86-97
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    • 2009
  • RTLS is a system for automatically locating and tracking people and objects. The TDOA-based RTLS determines the location of the tag by calculating the time differences of a signal received from the tag. In TDOA-based RTLS, time synchronization is essential to calculate the time difference between readers. This paper presents a precision time synchronization method for TDOA-based RTLS over IEEE 802.15.4. In order to achieve precision time synchronization in IEEE 802.15.4 radio, we analyzed the error factors of delay and jitter. We also deal with the implementation of hardware assisted time stamping and the Kalman filtering method to minimize the error factors. In addition, this paper described the experiments and performance evaluation of the proposed precision time synchronization method in IEEE 802.15.4 radio. The results show that the nodes in a network can maintain their clocks to within 10 nanoseconds offset from the reference clock.

A Novel Ambiguity Resolution Method of Radar Pulses using Genetic Algorithm (유전 알고리즘 기반 레이더 펄스 모호성 해결방법)

  • Han, Jinwoo;Jo, Jeil;Kim, Sanhae;Park, Jintae;Song, Kyuha
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.4
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    • pp.184-193
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    • 2015
  • Passive Surveillance System based on the TDOA detects the emitter position in the air using TOA of pulses comprising emitter signal from multiple receivers. In case that PRI of pulses from the emitter is not enough big in comparison with the distance among receivers, it causes the ambiguity problem in selecting proper pulse pairs for TDOA emitter geolocation. In this paper, a novel ambiguity resolution method of radar pulses is presented by using genetic algorithm after changing ambiguity problem into optimization problem between TDOA of received pulses from each receiver and emitter position. Simulation results are presented to show the performance of the proposed method.

A TDOA Sign-Based Algorithm for Fast Sound Source Localization using an L-Shaped Microphone Array

  • Yiwere, Mariam;Rhee, Eun Joo
    • Journal of Information Technology Applications and Management
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    • v.23 no.3
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    • pp.87-97
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    • 2016
  • This paper proposes a fast sound source localization method using a TDOA sign-based algorithm. We present an L-shaped microphone set-up which creates four major regions in the range of $0^{\circ}{\sim}360^{\circ}$ by the intersection of the positive and negative regions of the individual microphone pairs. Then, we make an initial source region prediction based on the signs of two TDOA estimates before computing the azimuth value. Also, we apply a threshold and angle comparison to tackle the existing front-back confusion problem. Our experimental results show that the proposed method is comparable in accuracy to previous three microphone array methods; however, it takes a shorter computation time because we compute only two TDOA values.

Improvement of TDOA-Based Localization Method for Port Logistics Environment (항만 물류 환경을 위한 TDOA 기반 측위 기법의 개선)

  • Choi, Hoon;Ji, Dong-Hwan;Baek, Yun-Ju
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.2B
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    • pp.99-106
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    • 2009
  • The tracking information of objects or persons plays the important role for being advanced of the technology in the logistics management or processing. In this paper, we propose the TDOA-based localization method for port logistics environment for obtaining accurate location of a tag which is attached to some objects or persons. The proposed method consists of these modules for precision : An adaptive selection module of base reader, 2.5D locating method and position-restriction method using a map. This paper includes the performance evaluation of those methods. We could see the improved performance in the simulation. And we also implemented the system and achieved the accuracy of DRMS and CEP within 4 meters.

Effect of mobile terminal searcher on TDOA position location technique (TDOA 위치추정기법에서의 단말기 Searcher의 영향)

  • 김정태;서덕영
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.7A
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    • pp.1022-1027
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    • 1999
  • This paper proposes method that uses Time-Difference-of-Arrival(TDOA) of Forward Pilot signals from base stations(BS) arriving at a mobile station(MS) as a position location method of CDMA MS. MS searcher does acquisition of BS Pilot signals and measurement of TDOAs. In order to do it, its processing gain is very important. Proportional relationship of the gain to the signal coherent integration interval is theoretically derived and analyzed and field test is performed to show acquisition of weak Pilot signals and stable measurements of TDOA values by increasing the gain. Also, signal strength decrease exponentially by the distance it travels. Therefore, improvement of the searcher gain makes possible to acquire Pilot signals at a location far away from BS. Variation of possible position estimation area relative to the signal strength within a cell is simulated with computer. Neglecting shadow effect it indicated necessity of detecting signals below -35dB in order to cover over 90% of cell area. Thus, efforts to maximize searcher coherent integration interval in order to acquire weak Pilot signals are required for expansion of position estimation area and measurement of stable TDOA values.

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