• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.7
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• pp.83-91
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• 1993

A ghost cancelling method using the multiplicationless adaptive multipath channel identification is proposed. The IIR filter and the LMS algorithm are used for ghost cancelling. The coefficients of IIR filter are obtained by multipath channel identification. The LMS algorithm which is simple relatively is used as the adaptive algorithm. An MPS is selected as the reference signal and it is used as the input of the adaptive algorithm for the multipath channel identification. If an MPS is not exist, the horizontal syne, and color burst signal can be used as the reference signal. Improving of accuracy of the ghost cancelling in the presence of the phase variation in the multipath channel, a complex processing are also performed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.5
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• pp.472-485
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• 1989

This paper represents the occurrence structure of the timing variation of TV horizontal synchronizing pulse(H-sync pulse) in mobile TV reception. Fluttering ghost is caused by timing varations of the H-sync pulse and is due to frequency elective fading in a multipath propagation envoronment. H-sync timing fluctuations, and hence, fluttering ghost are directly correlated with the multipath parameters, i.e., H-sync timing fluctuations reflect well the severity of the multipath environment. The occurrence structure of H-sync timtng fluctuation is analysed theoretically in relation to the multipath environnment. The occurrence structure of H-sync timing fluctuation is analysed theoretically in relation to the multipath parameters, assuming the two-ray propagation model. The H-sync timing fluctuation occurs with the variation in relative phase and /or D/U variation of long-delayed multipath waves.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.8
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• pp.27-33
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• 1993

This paper presents a mobile measurement technique of the ghost-flutter caused in mobile television reception. The ghost-flutter is caused by timing variation of the television horizontal synchronizing pulse due to frequency selective fading in a multipath propagation environment. The ghost-flutter can be detected by measuring the dynamic timing variation of horizontal synchronizing pulse. Especially, in this paper, a technique for measuring horizontal synchronizing timing fluctuations which cause the ghost-flutter is developed, using a Rubidium oscillator as a time standard with high stability.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.5
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• pp.532-537
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• 2015

In this paper, we propose target range estimation method using ghost target in the submarine linear array sonar. Usually, when submarine detect target, they use passive sonar detection to avoid self-disclosure by active sonar transmission. But, originally, passive linear array sonar have limitation for target range estimation and additional processing is required to get target range information. For the case of near-field target, typical range estimation method is using multiple information by multipath effect in underwater environment. Acoustic signal generated from target are propagated along with numerous multipath in underwater environment. Since multipath target signals received in the linear array sonar have different conic angles each other, ghost target is appeared at the bearing different with real target bearing and sonar operator can find these information on the operation console. Under several assumption, this geometric properties can be analysed mathematically and we get the target range by derivation of this geometric equations using measured conic angles of real target and ghost target.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.3
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• pp.52-60
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• 1993

Fluttering ghost which is the most severs picture impairment in mobile TV reception under multipath fading environments can be detected by measuring the dynamic variation of the synchronizing pulse timing. And also, the occurrence-stucture of fluttering ghost are directly correlated with the multipath parameters. This paper describes the quantitative evaluating method of the mobile TV pictures impaired by multipath parameters by means of the spectral analysis of synchronizing timing fluctuation. The ghost-flutter curve derived from the spatial amplitue spectrum of synchronizing pulse timing fluctuation express well the spatial variation characteristic, and it has been found to be the quantitative evaluating measure of picture impairment in mobile reception. A correspondence between the ghost-flutter curve (and/or index) and picture quality opinion test results is established.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.29 no.3
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• pp.229-235
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• 1993

In this paper, a method of ghost cancelling for the television signals using complex adaptive filter is studied. The sin(x)/x signal is used as the reference signal a complex adaptive filter. The ghost cancelling characteristics considering the delay time, the attenuation, and the phase difference of multipath waves are investigated using horizontal sync pulse and color burst signal in composite video waveform. The influences of phase difference in ghost cancelling are investigated and the performances between the real processing and the complex processing are compared by the computer simulation. It was found that influences in ghost by phase difference are remarkably reduced by the complex adaptive filtering.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.904-906
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• 1995

Based on the detection of the size of datas of multipath channel characterization, we propose a new algorithm. called the impulse size based adaptive median filter(ISMF), for ghost cancellation system. The ISMF consists of two levels. The first one is the impulse noise size detection level and the second one is the adaptive median filtering level to remove the impulse noise detected. Test results confirm that the proposed ISMF removes impulse noise due to multipath channel characterization while preserving signal as well as ghosts so that the LMS algorithm performs effectively.

• Journal of the Korea Computer Industry Society
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• v.6 no.5
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• pp.675-686
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• 2005

This paper proposes a new method of mathematically modeling and computer simulating television ghosts wherein television signals that have undergone multipath fading are generated without using approximations by considering the attenuation, time delay, phase, and timing jitter between consecutive frames. Conventional methods used polynomial interpolation or complex arithmetic to take into account the ghost phase, but our method uses only real arithmetic by employing the Hilbert transform and also reduces the computation time using the FFT (fast Fourier transform) algorithm. Furthermore, it is also possible to observe the transmit waveforms in both RF and IF ranges. Various ghost patterns generated in software provide for essential data required for the development of ghost canceling algorithms, and are deemed to be very useful in analyzing the constituent blocks of the transmitter and receiver chain in television broadcasting. The development of ghost cancelers needs to be preceded by the task of mathematically modeling ghosts and their extensive computer simulations.

• ETRI Journal
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• v.40 no.3
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• pp.376-388
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• 2018

In through-the-wall radar imaging (TWRI), the presence of front and side walls causes multipath propagation, which creates fake targets called multipath ghosts. They populate the scene and reduce the probability of correct target detection, classification, and localization. In modern TWRI, specular multipath exploitation has received considerable attention for reducing the effects of multipath ghosts. However, this exploitation is challenged by the requirements of the reflecting geometry, which is not always available. Currently, the demand for a high radar image resolution dictates the use of a large aperture and wide bandwidth. This results in a large amount of data. To tackle this problem, compressive sensing (CS) is applied to TWRI. With CS, only a fraction of the data are used to produce a high-quality image, provided that the scene is sparse. However, owing to multipath ghosts, the scene sparsity is highly deteriorated; hence, the performance of the CS algorithms is compromised. This paper presents and discusses the adverse effects of multipath ghosts in TWRI. It describes the physical formation of ghosts, their challenges, and existing suppression techniques.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.191-195
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• 2006

국내와 북미 지역에서 ATSC DTV 방송 서비스가 시작된 이래 수신 성능을 개선하기 위한 계속적인 노력이 경주되어 왔다 [1]-[6]. 본 논문에서는 2005 년 8 월 캐나다 CRC (Communications Research Center) 센터의 테스트 결과를 토대로 최신 ATSC 수신기의 성능을 고찰해 보고자 한다 [4]. CRC 테스트는 수신 감도, 다중 경로 환경에서의 수신 성능, 간섭 신호에 대한 강건성 등 다양한 항목에 걸려 실시되었으며, A/74 권고안에 기술된 난시청 지역의 50 개 신호 샘플에 대한 성능 평가를 포함하고 있다. 테스트에 사용된 ATSC 수신기는 당사에서 개발한 최신 칩 (GEMINI)을 탑재한 것으로 파일럿 (pilot) 신호가 손상된 경우에도 안정적인 동기 획득이 가능하며 현존 수신기 중 가장 넓고 강력한 반사파 (ghost) 제거 성능을 보유하고 있다. CRC 테스트 결과와 국내외 필드테스트 결과는 최신 ATSC 수신기가 A/74 권고안뿐만 아니라 각종 성능 지표에서 이전 수신기에 비해 대폭 개선되었음을 확인시켜 준다.