• Title, Summary, Keyword: Ambiguity plane

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Wigner-Ville Distribution Applying the Rotating Window and Its Characteristics (회전 창문함수를 적용한 위그너-빌 분포함수와 그 특성)

  • 박연규;김양한
    • Journal of KSNVE
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    • v.7 no.5
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    • pp.747-756
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    • 1997
  • Wigner-Ville distribution which is a time-frequency analysis has a fatal drawback, when the signal has multiple components. This is the cross-talk and often causes a neagative value in the distribution. Wingner-Ville distriution is an expression of power, therefore the cross-talk must be avoided. Smoothing the Wigner-Ville distribution by convoluting it with a window, is most commonly used to reduce the cross-talk. There can be infinite number of distributions depending on the windows. But, the smoothing reduces resolution in time-frequency plane; this motives to design a more effective window in reducing cross-talk while remaining resolution. The domain in which the cross-talk and legitimate components can be easily distinguished, is the ambiguity function. In the ambiguity function domain, the legitimate components appear as linear lines passing through the orgine. But, the cross-talk is widely distributes in the ambiguity function plane. Based on the relative distributions of cross-talk and legitimate components, rotating window can be designed to minimize cross-talk. Applying the rotating window to the ambiguity function corresponds to smoothing the Wigner-Ville distribution. Therefore, the effects of rotating window is estimated in terms of the bias error due to smooting the Wigner-Ville distribution. By applying the rotating window, not only the Wigner-Ville distribution but also its properties are changed. The properties of the new distribution are checked, in order to complete analyzing the rotating window.

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The Characteristics of Contiguous Pulse Trains of Stepped FM Signals with binary Phase Coding (2진위상 부호화 연속 펄스 계단 FM 신호의 특성)

  • 윤태환;박송배
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.15 no.6
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    • pp.79-86
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    • 1978
  • The characteristics of contiguous pulse trains of stopped FM signals with binary phase coding, to be used as radar signals, were investigated. For this purpose, the general expressions for the spectra and the ambiguity functions of this class of signals were first obtained; these expressions were then compute6 and plotted by the use of computer for various coding scheme. The results show that alternate phase coding provides the best time resolution and the corresponding ambiguity functon has a configuration of "be6 of spikes" in the whole time-velocity plane.ity plane.

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A Fast Integer Ambiguity Resolution Method For Precise Positioning On- The-Fly (OTF 정밀측위를 위한 신속한 미지정수 결정방법)

  • 이대규;성태경
    • Journal of Institute of Control, Robotics and Systems
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    • v.10 no.5
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    • pp.458-463
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    • 2004
  • This paper presents a fast IA(integer ambiguity) resolution method that determines the IA within short epochs with guaranteed reliability. Based on the fact that the search volume and the cost function are influenced by the selection of primary IAs in the plane intersection method, an IA resolution method is proposed that evaluates IA candidates repeatedly in an epoch with different combinations of primary IAs. In order to guarantee the reliability of the resolved IA with a certain probability, an inequality condition for selecting differencing operator is derived. Experiment results show that the proposed method consistently provides the true IA estimates within short time.

The Accuracy Analysis of RTK-GPS by Field Calibration in Plane Surveying (국지측량에서의 현장 Calibration에 의한 RTK-GPS 정확도 분석)

  • Park, Woon-Yong;Shin, Dong-Soo
    • Journal of Korean Society for Geospatial Information System
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    • v.10 no.2
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    • pp.87-95
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    • 2002
  • Real-time Kinematic GPS enables high accuracy Positioning by real time. If ambiguity use an integer solution, can obtain accuracy of several 'mm', and can obtain accuracy of tens 'em' if use real solution. In this study, We accomplish surveying by existent traditional surveying techniques (Total Station), Static GPS techniques and RTK-GPS techniques by Field Calibration about uniformity measuring point and then compared and ana1yzed each techniques positioning accuracy etc.. Result that achieve by Static-GPS in Plane area, about all measuring points, expressed error fewer than 3cm. Result that achieve RTK-GPS Surveying by Field Calibration in Plane area, could know that RTK-GPS techniques by Field Calibration is available in Plane area because expressing errors fewer than all 6cm, except case that do not get fixed solution of ambiguity Field Calibration RTK-GPS could know economically than existent conventional type measurement and existent GPS's measurement techniques that efficiency is very high.

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A Method to Reduce the Cross-Talk of Wigner-Ville Distribution;Rotating Window (위그너-빌 분포함수에서의 혼신성분 저감 방법 - 회전 창문함수)

  • 박연규;김양한
    • Journal of KSNVE
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    • v.7 no.2
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    • pp.319-329
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    • 1997
  • Wigner-Ville distribution has been recognized as a useful tool and applied to various types of mechanical noise and vibration signals, but its limitation which mainly comes from the cross-talk has not been well addressed. The cross-talk takes place for a signal with multiple components, simply because the Wigner-Ville distribution is a bilinear transform. The cross-talk often causes a negative value in the distribution. This cannot be accepted for the Wigner- Ville distribution, because it is an expression of power. Smoothing the Wigner-Ville distribution by convoluting it wih a window, is most commonly used to reduce the cross-talk. There can be infinite number of distributions depending on the windows. In this paper, we attempted to develop a distribution which is the best or the optimal in reducing the cross-talk. This could be possible by employing the ambiguity function. For a general signal, however it is difficult to express the ambiguity function as a mathematically closed form. This requires an appropriate modeling to make such expression possible. We approximated the Wigner-Ville distribution as a sum of linear segments. In the ambiguity function domain, the legitimate components are reflected as linear lines passing through the origin. Every lines has its own length and slope. But, the cross-talk is widely distributed in the ambiguity function plane. Based on this realization, we proposed a two-dimensional window which is in fact 'rotating window', that can eliminate cross-talk component. The rotating window is examined numerically and is found to have a better performance in reducing the cross-talk than conventional windows, the Gaussian window.

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A Study of World Map Building for Mobile Robot with Tri-Acral Ultrasonic Sensor System (세 개의 초음파 센서를 사용한 이동 로보트용 월드 맵 구성에 관한 연구)

  • 전형조;김병국
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.32B no.6
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    • pp.840-848
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    • 1995
  • A new tri-aural ultrasonic sensor system is suggested to build more accurate world maps for mobile robots with less scanning. In ordinary single sensor systems, the inherent beam-width of sonar transmitter causes ambiguity in sensing direction. Dual sensors may be used to discriminate plane and corner with several scans. However, the proposed method uses triple sensors, and achieves more accuracy with less scanning.

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Observation of Supersymmetry in Rigid Symmetric Top Rotor

  • Sun, Ho-Sung
    • Bulletin of the Korean Chemical Society
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    • v.27 no.4
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    • pp.515-518
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    • 2006
  • It is explicitly shown that a supersymmetry structure exists in the spectrum of a rigid symmetric top rotor in the molecule-fixed frame. Using projection operators constructed from the time-reversal symmetry of the rotor, the full rotor Hamiltonian is separated into two parts, i.e., the bosonic and fermionic components. The construction, without ambiguity, suggests that the rotor has a supersymmetry in it. This supersymmetry is mathematically equivalent to that of the free rotor on a plane recently noted by Rau.

Z-map Model Using Triangular Grids (삼각 격자를 이용한 Z-map 모델)

  • Park, Pae-Yong;Ahn, Jeong-Ho
    • Proceedings of the KSME Conference
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    • pp.824-828
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    • 2000
  • Prior to the downloading of the NC codes to a machining center, the NC tool-path can be verified in a computer. The Z-map is one of the tools for the verification of NC tool-path. The Z-map is a two dimensional array in which the height values of the Z-axis direction vectors are stored. The Z-axis direction vectors are arranged in a rectangular grid pattern on the XY plane. The accuracy of the simulation comes from the grid interval. In the rectangular Z-map, the distances between the grid points are different. The distance in diagonal direction is larger than those in X or Y axis directions. For the rendering of the Z-map, a rectangular grid is divided into two triangular facets. Depending on the selection of a diagonal, there are two different cases. In this paper, triangular Z-map, in which the Z-axis direction vectors are arranged in a triangular grid pattern on XY plane, is proposed. In the triangular Z-map, the distances between grid points are equal. There is no ambiguity to make triangular facets for the rendering.

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A $^{13}CO(1-0)$ Survey of the Second Quadrant of Galactic Plane I (은하면 제2상한 $^{13}CO(1-0)$ 탐사관측연구 I)

  • Lee, Young-Ung;Kim, Young-Sik;Kang, Hyun-Woo;Jung, Jae-Hoon;Lee, Chang-Hoon;Yim, In-Sung;Kim, Bong-Gyu;Kim, Hyun-Goo;Kim, Kwang-Tae
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.1
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    • pp.75.1-75.1
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    • 2012
  • We have observed the part of the second quadrant of the Galactic Plane in $^{13}CO(1-0)$ using the multibeam receiver system installed on the 14 m telescope at Taeduk Radio Astronomy Observatory. The target region (L=108 to 112.5) is the part of the $^{12}CO$ Outer Galactic Plane Survey (Heyer et al. 1998), and it is for the exact Galactic plane with the latitude range of +1 and -1 degree. Total of 48,000 spectra (about 9 square degees) were obtained on 50" grid. The selected velocity resolution is 0.63 km/sec and sensitivity per channel is 0.17 K, and the covered velocity is 320 km/sec. We developed a new reduction method, which effectively deals with a relatively noisy 3-dimensional database. The collected $^{13}CO$ database will be manipulated with pre-existing $^{12}CO$ data to get several physical parameters. As it is located in the second quadrant, the kinematic distances of the individual clouds, which will be identified, can be estimated relatively easily without any distance ambiguity. In this meeting we present the reduction method, statistics, and some channel maps, integrated intensity maps, and spatial-velocity maps. We intend to clarify any difference of their characteristics between the clouds in the Outer Galaxy and Inner Galaxy using our data base.

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