• Title/Summary/Keyword: time of arrival range

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Time of Arrival range Based Wireless Sensor Localization in Precision Agriculture

  • Lee, Sang-Hyun;Moon, Kyung-Il
    • International journal of advanced smart convergence
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    • v.3 no.2
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    • pp.14-17
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    • 2014
  • Precision agriculture relies on information technology, whose precondition is providing real-time and accurate information. It depends on various kinds of advanced sensors, such as environmental temperature and humidity, wind speed, light intensity, and other types of sensors. Currently, it is a hot topic how to collect accurate information, the main raw data for agricultural experts, monitored by these sensors timely. Most existing work in WSNs addresses their fundamental challenges, including power supply, limited memory, processing power and communication bandwidth and focuses entirely on their operating system and networking protocol design and implementation. However, it is not easy to find the self-localization capability of wireless sensor networks. Because of constraints on the cost and size of sensors, energy consumption, implementation environment and the deployment of sensors, most sensors do not know their locations. This paper provides maximum likelihood estimators for sensor location estimation when observations are time-of arrival (TOA) range measurement.

Analysis of TDOA and TDOA/SS Based Geolocation Techniques in a Non-Line-of-Sight Environment

  • Huang, Jiyan;Wan, Qun
    • Journal of Communications and Networks
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    • v.14 no.5
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    • pp.533-539
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    • 2012
  • The performance analysis of wireless geolocation in a non-line-of-sight (NLOS) environment is a very important issue. Since Cramer-Rao lower bound (CRLB) determines the physical impossibility of the variance of an unbiased estimator being less than the bound, many studies presented the performance analysis in terms of CRLB. Several CRLBs for time-of-arrival (TOA), pseudo-range TOA, angle-of-arrival (AOA), and signal strength (SS) based positioning methods have been derived for NLOS environment. However, the performance analysis of time difference of arrival (TDOA) and TDOA/SS based geolocation techniques in a NLOS environment is still an opening issue. This paper derives the CRLBs of TDOA and TDOA/SS based positioning methods for NLOS environment. In addition, theoretical analysis proves that the derived CRLB for TDOA is the same as that of pseudo-range TOA and the TDOA/SS scheme has a lower CRLB than the TDOA (or SS) scheme.

Range estimation of underwater vehicles using superimposed chirp signals (중첩된 처프 신호를 이용한 수중 이동체의 거리 추정)

  • Hyung-in Ra;Kyung-won Lee;Chang-hyun Youn;Ki-man Kim
    • The Journal of the Acoustical Society of Korea
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    • v.42 no.6
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    • pp.511-518
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    • 2023
  • Accurate ranging is one of the key factors in the test and evaluation process of underwater vehicles. In particular, when estimating range using Time of Arrival (ToA) values, signals such as Linear Frequency Modulation (LFM), a chirp signal, are highly applicable due to their correlated nature. However, in a Doppler shift environment with mobility, measurement errors may occur due to the range-Doppler coupling effect. In this paper, we propose a signal that compensates for the distance-Doppler coupling effect to reduce the measurement error of the arrival time value. The proposed signal is constructed by superimposing two types of LFM signals, and the range-Doppler coupling effect can be minimized. Through simulations, it is confirmed that the proposed signal is a way to compensate for the distance-Doppler coupling effect in the distance estimation of underwater mobile bodies, reducing the measurement error of the arrival time value.

Impact point estimation system of the rifle based on time difference of arrival method using microphone array (마이크로폰 어레이를 이용한 도착 시간 차 기반 소총화기 탄착점 추정 시스템)

  • Won, Jongseong;Park, Kyusik
    • The Journal of the Acoustical Society of Korea
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    • v.37 no.4
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    • pp.206-214
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    • 2018
  • This paper proposes an impact point estimation algorithm of the rifle using microphone sensors. The proposed algorithm resolves the time synchronization problem by expanding the existing ToA (Time of Arrival) method to TDoA (Time Difference of Arrival) method and verifies the performance of the algorithm through the actual shooting experiments. By comparing analysis of the actual and the estimated impact points by the algorithm, it is confirmed that the proposed algorithm has excellent performance by estimating the impact point accurately within the tolerance range.

A Study on the Optimal Appointment Scheduling for the Ship Maintenance with Queueing System with Scheduled Arrivals (예약도착 대기행렬을 활용한 함정정비 최적 예약시간 산정에 관한 연구)

  • Ko, Jae-Woo;Kim, Gak-Gyu;Yun, Bong-Kyu
    • Journal of the Korean Operations Research and Management Science Society
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    • v.38 no.3
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    • pp.13-22
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    • 2013
  • Queueing system with scheduled arrivals is useful in many fields where both customers' waiting time and servers' operation time (utilization) are important, and arrival time of customers is possible to be controlled. In this paper, we analyzed the operation of ship maintenance with the queueing system with scheduled arrival. Based on the model presented by Pegden and Rosenshine [8], who dealt with exponential service time, we extended the service time distributions to phase-type distribution which is able to include a wide range of real stochastic phenomena. Since most activities in the military are carried out under tight control and schedule, scheduled arrival queue has quite good applicability in this area. In this context, we applied queue with scheduled arrival to the optimal booking time decision for the ship maintenance in the navy.

An Efficient Simulation of Discrete Time Queueing Systems with Markov-modulated Arrival Processes (MMAP 이산시간 큐잉 시스템의 속산 시뮬레이션)

  • Kook Kwang-Ho;Kang Sungyeol
    • Journal of the Korea Society for Simulation
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    • v.13 no.3
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    • pp.1-10
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    • 2004
  • The cell loss probability required in the ATM network is in the range of 10$^{-9}$ ∼10$^{-12}$ . If Monte Carlo simulation is used to analyze the performance of the ATM node, an enormous amount of computer time is required. To obtain large speed-up factors, importance sampling may be used. Since the Markov-modulated processes have been used to model various high-speed network traffic sources, we consider discrete time single server queueing systems with Markov-modulated arrival processes which can be used to model an ATM node. We apply importance sampling based on the Large Deviation Theory for the performance evaluation of, MMBP/D/1/K, ∑MMBP/D/1/K, and two stage tandem queueing networks with Markov-modulated arrival processes and deterministic service times. The simulation results show that the buffer overflow probabilities obtained by the importance sampling are very close to those obtained by the Monte Carlo simulation and the computer time can be reduced drastically.

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Energy Detector based Time of Arrival Estimation using a Neural Network with Millimeter Wave Signals

  • Liang, Xiaolin;Zhang, Hao;Gulliver, T. Aaron
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.7
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    • pp.3050-3065
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    • 2016
  • Neural networks (NNs) are extensively used in applications requiring signal classification and regression analysis. In this paper, a NN based threshold selection algorithm for 60 GHz millimeter wave (MMW) time of arrival (TOA) estimation using an energy detector (ED) is proposed which is based on the skewness, kurtosis, and curl of the received energy block values. The best normalized threshold for a given signal-to-noise ratio (SNR) is determined, and the influence of the integration period and channel on the performance is investigated. Results are presented which show that the proposed NN based algorithm provides superior precision and better robustness than other ED based algorithms over a wide range of SNR values. Further, it is independent of the integration period and channel model.

A Study on the Flaw Evaluation in the Straddle Mount Type Low Pressure Turbine Disc Using Phased Array Ultrasonic Technique (위상 배열 초음파 기법을 이용한 Straddle Mount형 저압 터빈 디스크 결함 평가에 관한 연구)

  • Yang, Seung-Han;Yoon, Byung-Sik;Kim, Yong-Sik
    • Journal of the Korean Society for Nondestructive Testing
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    • v.26 no.4
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    • pp.231-238
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    • 2006
  • Nondestructive examination for low pressure turbine disc in standard nuclear power plant using phased array technique was studied. For this purpose, disc mockups were made and notches were machined in the mockups. Detection and length sizing by different methods are compared. Depth of deep notches could be measured by using AATT(absolute arrival time technique) or RATT(relative arrival time technique) but shallow notches that must be detected in early stage couldn't be measured by these two methods. For this case, notch depth was estimated by using signal response angle range and preyed usefulness.

An Improved ToA Estimation in a Compressed Sensing-based UWB System (압축센싱 기반의 UWB 시스템에서 개선된 ToA 추정 기법)

  • Le, Tan N.;Kim, Kwang-Yul;Shin, Yo-An
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.6C
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    • pp.376-383
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    • 2011
  • Since the first arrival path may not be the strongest path of UWB(Ultra Wide Band) multipath channels, this makes ToA(Time-of-Arrival) estimation becomes a challengeable issue. Furthermore, because of ultra bandwidth of received signals, the compressed sensing theory is employed to reduce the complexity caused by very high Nyquist sampling rate in coherent UWB receivers. In this paper, we propose a ToA estimation scheme which provides precise estimation performance, while exploiting the benefits of compressed sensing-based UWB receivers. Simulation results show that the proposed scheme can outperform other low complexity schemes in a wide range of signal-to-noise ratios.

Construction of experimental data to calculate the arrival time of the rescue ship (구조선의 도착시간 산출을 위한 실험 데이터 구축)

  • Jeong, Jae-Yong;Jung, Cho-Young
    • Journal of Advanced Marine Engineering and Technology
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    • v.41 no.1
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    • pp.111-117
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    • 2017
  • The arrival time of rescue ships is very important in the event of distress. This paper presents the development of experimental data to calculate the arrival time of rescue ships. The ship's traffic probability distribution was used. Mokpo Port was selected as the area of study, and AIS data for a 1 year period were used. For the ship's traffic probability distribution, a gateline was established. The lateral range distribution was calculated and fitted to the normal distribution and two Gaussian mixture distributions (GMD2), and each parameter was extracted. After the locations of ${\mu}$, ${\mu}{\pm}1{\sigma}$ of the normal distribution and ${\mu}_1$ of the two Gaussian mixture distribution(GMD2) were set as waypoints, the location and probability were determined. A scenario was established in relation to each type of parameter. Thus, the arrival time can be calculated.