• 제목/요약/키워드: Bias Timing

검색결과 47건 처리시간 0.021초

M-BECM의 타이밍 검출기 출력 특성 분석 (Analysis of the Timing Detector's Characteristics of the Modified BECM(M-BECM) Algorithm)

  • 이경하;김용훈;최형진
    • 전자공학회논문지S
    • /
    • 제34S권7호
    • /
    • pp.28-38
    • /
    • 1997
  • Previously, we have proposed the M-BECM(Modified-Band Edge Component Maximization), which is a symbol synchronization algorithm based on spectral line method for all-digital high speed digital communications. However, Until now, the characteristics of the timing detector based on the spectral line method including M-BECM was not analyzed, particularly the effect of a timing offset at the optimal convergence pont. In this paper, we analyze the timing dtector's characteristics of the M-BECM and present optimal design value. First, the expression for the timing detector's mean value(often called its S-Curver) as a function of the normalized symbol timing offset is derived. Next, the P $D_{bias}$, the value for compensating the timing offset at an optimal convergence point, and the bandwidth of bandpass filter in the timing detector are calculated. It is also shown and analyzed that the P $D_{bias}$ is affected by varuous factors such as the excess bandwidth of input signal, frequency offsets, noise and particularly, the excess bandwidth of input signal is a major parameter to decide P $D_{bias}$. Finally, analytic resutls are compared to simulation results.

  • PDF

SDINS에서 의사 자이로 바이어스 보상 기법 (Compensation of Pseudo Gyro Bias in SDINS)

  • 박정민
    • Journal of Positioning, Navigation, and Timing
    • /
    • 제13권2호
    • /
    • pp.179-187
    • /
    • 2024
  • The performance of a Strapdown Inertial Navigation System (SDINS) relies heavily on the accuracy of sensor error calibration. Systematic calibration is usually employed when only a 2-axis turntable is available. For systematic calibration, the body frame is commonly defined with respect to sensor axes for ease of computation. The drawback of this approach is that sensor axes may undergo time-varying deflection under temperature change, causing pseudo gyro bias. The effect of pseudo gyro bias on navigation performance is negligible for low grade navigation systems. However, for higher grade systems undergoing rapid temperature change, the error is no longer negligible. This paper describes in detail conditions leading to the presence of pseudo gyro bias, and proposes two techniques for mitigating the error. Experimental results show that applying these techniques improves navigation performance for precision SDINS, especially under rapid temperature change.

Design of an Error Model for Performance Enhancement of MEMS IMU-Based GPS/INS Integrated Navigation Systems

  • Koo, Moonsuk;Oh, Sang Heon;Hwang, Dong-Hwan
    • Journal of Positioning, Navigation, and Timing
    • /
    • 제1권1호
    • /
    • pp.51-57
    • /
    • 2012
  • In this paper, design of an error model is presented in which the bias characteristic of the MEMS IMU is taken into consideration for performance enhancement of the MEMS IMU-based GPS/INS integrated navigation system. The drift bias of the MEMS IMU is modeled as a 1st-order Gauss-Markov (GM) process, and the autocorrelation function is obtained from the collected IMU data, and the correlation time is estimated from this. Prior to obtaining the autocorrelation function, the noise of IMU data is eliminated based on wavelet. As a result of simulation, it is represented that the parameters of error model can be estimated correctly only when a proper denoising is performed according to dynamic behavior of drift bias, and that the integrated navigation system based on error model, in which the drift bias is considered, provides more correct navigation performance compared to the integrated navigation system based on error model in which the drift bias is not considered.

Extended Kalman Filter Based GF-INS Angular Velocity Estimation Algorithm

  • Kim, Heyone;Lee, Junhak;Oh, Sang Heon;Hwang, Dong-Hwan;Lee, Sang Jeong
    • Journal of Positioning, Navigation, and Timing
    • /
    • 제8권3호
    • /
    • pp.107-117
    • /
    • 2019
  • When a vehicle moves with a high rotation rate, it is not easy to measure the angular velocity using an off-the-shelf gyroscope. If the angular velocity is estimated using the extended Kalman filter in the gyro-free inertial navigation system, the effect of the accelerometer error and initial angular velocity error can be reduced. In this paper, in order to improve the navigation performance of the gyro-free inertial navigation system, an angular velocity estimation method is proposed based on an extended Kalman filter with an accelerometer random bias error model. In order to show the validity of the proposed estimation method, angular velocities and navigation outputs of a vehicle with 3 rev/s rotation rate are estimated. The results are compared with estimates by other methods such as the integration and an extended Kalman filter without an accelerometer random bias error model. The proposed method gives better estimation results than other methods.

바이어스 타이밍 기법을 이용하여 송수신 격리도가 개선된 소형 송수신 모듈 (Compact T/R Module Having Improved T/R Isolation Using a Bias Timing Scheme)

  • 박성균;이해영
    • 한국전자파학회논문지
    • /
    • 제23권12호
    • /
    • pp.1380-1387
    • /
    • 2012
  • 송수신(T/R) 모듈은 능동 위상 배열 시스템에서 핵심 부품이다. 현재 가장 널리 적용되고 있는 모듈 구조는 Brick 형태로서 이를 소형화 하는 것은 전체 시스템 구성의 유연성을 확보할 수 있는 중요한 요소가 된다. 소형화를 위하여 MMIC 갯수를 최소화 할 수 있는 Common leg 구조를 갖는 MFC(Multi Fuction Chip) 사용이 유리하며, 이득이 높은 T/R 모듈을 고밀도로 구현하기 위하여 송수신간 격리도의 확보가 필수적이다. 본 논문에서는 Common leg 구조에서 불가피하게 발생하는 궤환 경로 문제와 이로 인한 송수신 격리도의 한계를 개선하기 위하여 바이어스 전압 제어 방법을 제안하고, 측정 결과를 기반으로 최적 바이어스 타이밍을 설계하였다. 본 논문에서 제작/측정된 TR 모듈은 일반 T/R 모듈에 비하여 약 1/2의 크기($140{\times}80{\times}16mm^3$)를 가지며, 높은 출력(채널당 7 W)과 높은 송수신 이득(35 dB 송신 이득과 30 dB 수신 이득)의 구현이 가능하였다.

Highly integrated LCD bias and control IC

  • Nachbaur, Oliver
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
    • /
    • pp.1236-1239
    • /
    • 2009
  • Each LCD TFT panel requires a power supply IC on the panel board. The IC provides the power rails for the timing controller, source and gated driver IC and others. The industry trend moves towards higher integrated devices. The challenge for the panel manufacturer is the development and implementation of such an IC in cooperation with the semiconductor supplier. If not done carefully the solution will not reduce the overall solution cost or can't provide the expected performance and reliability. This paper discusses the key considerations to successfully develop and integrate a highly integrated LCD bias IC into the system.

  • PDF

Bearing-only Localization of GNSS Interference using Iterated Consider Extended Kalman Filter

  • Park, Youngbum;Song, Kiwon
    • Journal of Positioning, Navigation, and Timing
    • /
    • 제9권3호
    • /
    • pp.221-227
    • /
    • 2020
  • In this paper, the Iterated Consider Extended Kalman Filter (ICEKF) is proposed for bearing-only localization of GNSS interference to improve the estimation performance and filter consistency. The ICEKF is an extended version of Consider KF (CKF) for Iterated EKF (IEKF) to consider an effect of bearing measurement bias error to filter covariance. The ICEKF can mitigate the EKF divergence problem which can occur when linearizing the nonlinear bearing measurement by a large initial state error. Also, it can mitigate filter inconsistency problem of EKF and IEKF which can occur when a weakly observable bearing measurement bias error state is not included in filter state vector. The simulation result shows that the localization error of the ICEKF is smaller than the EKF and IEKF, and the Root Mean Square (RMS) estimation error of ICEKF matches the covariance of filter.

Test Results of Wide-Area Differential Global Positioning System with Combined Use of Precise Positioning Service and Standard Positioning Service Receiver

  • Kim, Kap Jin;Ahn, Jae Min
    • Journal of Positioning, Navigation, and Timing
    • /
    • 제10권1호
    • /
    • pp.43-48
    • /
    • 2021
  • Most existing studies on the wide-area differential global positioning system (WADGPS) used standard positioning service (SPS) receivers in their observation reference stations which provide the central control station global positioning system (GPS) measurements to generate augmentation data. In the present study, it is considered to apply a precise positioning service (PPS) receiver to an observation reference station which is located in the threatened jamming area. Therefore, the reference station network consists of a PPS receiver based observation reference station and SPS receiver based observation reference stations. In this case, to maintain correction performance P1C1 differential code bias (DCB) should be compensated. In this paper, P1C1 DCB estimation algorithm was applied to the PPS/WADGPS system and performance test results using measurements in the Korean Peninsula were presented.

The Effect of Review Behavior on the Reviewer's Valence in Online Retailing

  • Oh, Yun-Kyung
    • 유통과학연구
    • /
    • 제15권10호
    • /
    • pp.41-50
    • /
    • 2017
  • Purpose - Online product review has become a crucial part of the online retailer's market performance for a wide range of products. This research aims to investigate how an individual reviewer's review frequency and timing affect her/his average attitude toward products. Research design, data, and methodology - To conduct reviewer-level analysis, this study uses 42,172 posted online review messages generated by 6,941 identified reviewers for 59 movies released in the South Korea from July 2015 to December 2015. This study adopts Tobit model specification to take into account the censored nature and the selection bias arising from the nature of J-shaped distribution of movie rating. Results - Our estimation results support that the negative impact of review frequency and timing on valence. Furthermore, review timing has an inverted-U relationship with the user's average valence and enhance the negative effect of review frequency. Conclusions - This study contributes to the growing literature on the understanding how eWOM is generated at the individual consumer level. On the basis of the main empirical findings, this study provides insights into building a recommendation system in online retail store based on the consumer's review history data - frequency, timing, and valence.

통합 의사잡음신호 기반 부호추적편이 추정에 따른 GPS L1 C/A 신호의 재방송재밍 영향 완화 기법 (A Novel Scheme to Mitigate a GPS L1 C/A Signal Repeat-back Jamming Effect, According to a Code Tracking Bias Estimation, Using Combined Pseudo-random Noise Signals)

  • 유승수;염동진;지규인;김선용
    • 제어로봇시스템학회논문지
    • /
    • 제22권10호
    • /
    • pp.869-875
    • /
    • 2016
  • In this paper, a novel scheme with which to mitigate a repeat-back jamming effect is proposed for the GPS L1 coarse/acquisition signal. The proposed scheme estimates the code tracking bias caused by repeat-back jamming signals using a Combined Pseudo-random noise signal. It then mitigates the repeat-back jamming effect by subtracting the estimated code timing on a normal correlation channel from the estimated value. Through a Monte-Carlo simulation, the proposed scheme can diminish the running average of code tracking bias to less than 10% of the bias using the conventional scheme.