• ETRI Journal
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• v.25 no.3
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• pp.171-178
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• 2003

To improve the detection performance of surveillance radars with polarization diversity, we developed an adaptive polarimetric processor and compared it with other polarimetric processors. We derived our adaptive polarimetric processor, called the polarization discontinuity detector (PDD), from the generalized likelihood ratio (GLR) test principle for the unspecified target component. We derived closed-form expressions of its probabilities of detection and false alarm, and compared its performance to that of the adaptive polarization canceller (APC) and Kelly's GLR processor. The PDD had a performance similar to Kelly's GLR in Gaussian clutter, and both the PDD and Kelly's GLR, which have embedded constant false alarm rates (CFARs), outperformed the APC, especially when the target polarization state was close to the clutter's polarization state. The important difference is that the PDD is much simpler than Kelly's GLR for hardware/software implementation, because the PDD does not require a costly two-parameter filter bank to cover the unknown target polarization state as Kelly's GLR does.

• ETRI Journal
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• v.35 no.5
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• pp.757-766
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• 2013

This paper deals with the estimation of the time of arrival (TOA) of ultra-wideband signals under IEEE 802.15.4a channel models. The proposed approach is based on a randomness test and consists of determining whether an autoregressive (AR) process modeling an energy frame is random or not by using a distance to measure the randomness. The proposed method uses a threshold that is derived analytically according to a preset false alarm probability. To highlight the effectiveness of the developed approach, simulation setups as well as real data experiments are conducted to assess the performance of the new TOA estimation algorithm. Thereby, the proposed method is compared with the cell averaging constant false alarm rate technique, the threshold comparison algorithm, and the technique based on maximum energy selection with search back. The obtained results are promising, considering both simulations and collected real-life data.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.252-255
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• 2000

In this paper, a fast pseudo-noise (PN) code acquisition with novel adaptive architecture is presented in direct-sequence spread- spectrum (DS-SS) systems. Since an existing acquisition system has a fixed correlation tap size and threshold value, this system cannot adapt to various mobile communication environments and results in a low detection probability or a high false alarm rate and long acquisition time. Therefore, if a correlation tap size and a threshold value can be controlled adaptively according to received signals, problems of ail existing system will be solved. The system parameter varies adaptively by using constant false alarm rate (CFAR) algorithm well known in a field of detection and proposed signal-to-noise ratio (SNR) measurement system. By deriving formulas of the proposed system, the performance is analyzed.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.18 no.1
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• pp.51-57
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• 2010

This study was to analyze the difference in pilot error by using the Signal Detection Theory. The task was to detect the targeted aircraft(signal) which is different shape from many other aircraft(noise). From the two experiments, we differentiated the task difficulty followed by change in noise stimuli. Experiment 1 was to search the signal stimuli(fighter plane) while the noise stimuli(cargo plane) were increasing. The results from the Experiment 1 showed the tendency to decrease the hit rate by increasing the number of noise stimuli. However, the false alarm rate was not increased. The sensitivity(d') showed quite high. In Experiment 2, a disturbance stimulus(helicopter) was added to noise stimuli. The result was generally similar to those of Experiment 1. However, the hit rate was lower than that of Experiment 1.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.338-341
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• 2013

본 논문에서는 동일 주파수 대역 내 DRM(Digital Radio Mondiale) Plus 신호와 FM(Frequeny Modulation) 신호가 모두 서비스 되는 Hybrid 방송 모드에 적합한 DRM Plus 신호 검출 기법을 제안한다. OFDM(Orthogonal Frequency Division Multiplexing) 신호의 Guard-Interval 상관 기법을 그대로 적용할 경우 DRM Plus 신호 검출 성능은 우수하나, FM 신호 수신 시 False Alarm 발생 확률이 증가하는 문제점이 발생한다. 제안한 방법은 Guard-Interval 상관 방법에 Reference 블록을 포함하고 있어, 약한 DRM Plus 신호에서도 판별 확률이 높고, 아날로그 FM 신호 수신 시 False Alarm이 발생할 확률이 낮은 특징이 있다. 모의 실험을 통하여 제안한 기법의 성능을 확인한다.

• Journal of information and communication convergence engineering
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• v.12 no.2
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• pp.97-103
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• 2014

In spectrum sensing, there is a tradeoff between the probability of missed detection and the probability of a false alarm according to the value of the sensing threshold. Therefore, it is important to determine the sensing threshold suitable to the environment of cognitive radio networks. In this study, we consider a cognitive radio-based ad hoc network where secondary users directly communicate by using the same frequency band as the primary system and control their transmit power on the basis of the distance between them. First, we investigate a condition in which the primary and the secondary users can share the same frequency band without harmful interference from each other, and then, propose an algorithm that controls the sensing threshold dynamically on the basis of the transmit power of the secondary user. The analysis and simulation results show that the proposed sensing threshold control algorithm has low probabilities of both missed detection and a false alarm and thus, enables optimized spectrum sharing between the primary and the secondary systems.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.163-165
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• 2009

Automatic Vision Inspection(AVI) systems automatically detect defect features and measure their sizes via camera vision. It is important to predict the performance of an AVI to meet customer's specification in advance. In this paper, we propose a statistical method for prediction of false alarm rate regarding inconsistency of defect size measuremet process. We only need are a simple experimental trial for repeated defect size measurement test. The statistical features from the experiement are utilized in the prediction process. Therefore, the proposed method is swift and easy to implement and use. The experiment shows a close prediction compared to manual inspection results.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.669-670
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• 2008

In this paper, we present a real-time system to detect abnormal events on gas pipes, based on the signals which are observed through the audio sensors attached on them. First, features are extracted from these signals so that they are robust to noise and invariant to the distance between a sensor and a spot at which an abnormal event like an attack on the gas pipes occurs. Then, a classifier is constructed to detect abnormal events using neural networks. It is a combination of two neural network models, a Gaussian mixture model and a multi-layer perceptron, for the reduction of miss and false alarms. The former works for miss alarm prevention and the latter for false alarm prevention. The experimental result with real data from the actual gas system shows that the proposed system is effective in detecting the dangerous events in real-time with an accuracy of 92.9%.

• Journal of electromagnetic engineering and science
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• v.13 no.3
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• pp.151-157
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• 2013

Marine radars are affected by sea and rain clutters, which can make target discrimination difficult. The clutter standard deviation and improvement factor are applied using multiple parameters-moving speed of radar, antenna speed, angle, etc. When a radar signal is processed, a Data Matrix Bank (DMB) filter can be applied to remove sea clutters. This filter allows detection of a target, and since it is not affected by changes in adjacent clutters resulting from a multi- target signal, sea state clutters can be removed. In this paper, we study the level for clutter removal and the method for target detection. In addition, we design a signal processing algorithm for marine radars, analyze the performance of the DMB filter algorithm, and provide a DMB filter algorithm design. We also perform a DMB filter algorithm analysis and simulation, and then apply this to the DMB filter and cell-average constant false alarm rate design to show comparative results.

• The Journal of the Acoustical Society of Korea
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• v.10 no.5
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• pp.69-76
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• 1991

본 논문에서는 통계적 방법에 의한 음소의 자동분할에 관한 알고리즘을 제안하였다. 우선 음성 신호를 AR 모델로 모델링한 후 스펙트럼이 변화하기 전과 변화한 후의 모델에 대해서 likelihood ratio 와 mutual information을 고려한 test statistics 로부터 모델 계수가 변화하는 곳을 예측해 내고 이 곳을 음소의 경계로 판단한다. 이 경우 검파되지 못하는 대부분의 음소는 짧은 자음이었으며 Signed front-to-back maximum area ratio을 이용하여 개선하였다. 또한 false alarm error을 줄이기 위해 두 segment 사이의 distortion 으로부터 smoothing을 하였다. 3명의 화자에 대한 실험 결과 non-detection error는 10%, false alarm error는 20% 정도로 나타났지만 화자간에 알고리즘의 성능 변화가 거의 없으 며 특히 분할된 경계치 분포는 전체 음소의 90% 이상이 이 30ms 이내에 위치하였다.