• Journal of the Korean Institute of Telematics and Electronics C
• /
• v.36C no.2
• /
• pp.62-67
• /
• 1999

Phase rotational is a practical problem in the implementation of coherent demodulation. Large phase noise may intorduce phase rotation in the demodulator which results in repeated decision errors. This paper presents a simple and yet very efficient technique in building a carrier recovery loop which minimizes the phase rotation by improving the stability of the decision-directed carrier recovery loop. Simulation shows this novel technique improves the performance of the carrier recovery loop as well as stability.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.26 no.9
• /
• pp.828-836
• /
• 2015

In this paper, the assessment technique for track accuracy in the phased array radar is proposed. It is assumed that ${\alpha}-{\beta}$ tracking filter to track the target is established in the phased array radar. In order to assess the track accuracy strictly, we should use the real target position data acquired from the special instrument, ACMI(Air Combat Maneuvering Instrument) pod or DGPS(Differential Global Positioning System). However, this method leads to increase the experiment cost and test time. We derive the relationship between the residuals of tracking filter and the standard deviations of range and angle tracking errors which are assigned as track assessment index. The theory of sample variance is introduced in this assessment because track accuracy has to be calculated with many residual samples.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.9 no.8
• /
• pp.1780-1786
• /
• 2005

The phase error generated in the transmission system affects the performance of digital transmission signal. The phase error are generated by random phase noise and tracking phase error due to denier phenomenon. In the mobile satellite communication system that generates the doppler frequency, which is a system with a movement, the proper system phase noise spectrum should be designed based on analyses for phase noise and static phase error effects. Based on the analyses of the doppler frequency and the phase error for bilateral satellite communication system providing an asynchronous service, the phase noise spectrums for the mobile satellite communication are designed in this paper. Also, the available transmission services under the less doppler effect are proposed and the proper signal source units for a required transmission system can be designed under the proposed system phase noise spectrum.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.10 no.1
• /
• pp.66-74
• /
• 1996

최근 진행파형 초음파 모터는 그 구조가 간단하고, 저속 고 토크이어서 직접 구동()용으로 많은 호응을 얻고 있다. 또한 응답이 빠르고, 정지 토크가 크며 설계자유도가 높을 뿐만 아니라 운전시 소음이 없고 자계에 강해 자동화 설비 분야 등 산업 전반에 걸쳐 매우 각광을 받고 있다. 본 논문에서는 초음파 모터의 2상 입력전원의 위상차를 조절하여 속도와 토크 특성을 이론적으로 고찰하고, 이를 토대로 위상차 제어기를 설계 제작하였다. 그리고 이를 이용하여 위상차 제어방식을 채용한 경우 초음파 모터의 위치 및 속도제어는 물론 간단한 알고리즘으로 토크 제어가 가능함을 시뮬레이션과 실험을 통하여 검토하였다. 실험 결과 위상차 변화에 따라 속도가 토크가 거의 비례해서 변화하였다. 이것으로 전원 전압의 위상차 조절을 통해서 속도와 토크를 동시에 제어할 수 있을 뿐만 아니라 토크센서 없이 각도 센선 만으로도 위치제어는 물론 토크 제어도 큰 오차 없이 행할 수 있음을 밝혔다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.10a
• /
• pp.355-356
• /
• 2018

An interferometer is antenna system composed fo two or more elements that can be used to determine the diretion of arrival (DOA) of a received signal by measuring the relative phase between receiving elements. In order to minimize the error of the direction-finding accuracy in interferometer direction-finding system (DFS), the phase correction is accomplished. In this paper, the several methods for the phase correction are classified and the advantage and disadvantage of those methods are compared.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.7
• /
• pp.657-666
• /
• 2002

In this paper, a new broadband phase shifter to adjust the slope of dispersive phase characteristic for frequency of transmission network was proposed. The new fundamental network consists of a fixed main line with a length of λ/2 at the center frequency and two double stubs, each with a length of λ/8 at the center frequency, which are open and shorted, respectively, and which are shunted at the edge points of the main line. Characteristic impedances of the main line and two parallel double stubs are adjusted to produce a minimum phase error and to obtain an input and output match at the desired phase shift. Especially, the proposed structure is especially suitable for a broadband phase shifter with large phase shifts more than 90$^{\circ}$, and it is operated in the octave bandwidth. To verify the usefulness of a new broadband phase shifter, each 45$^{\circ}$-, 90$^{\circ}$-, 180$^{\circ}$-bit phase shifter and 3-bit phase shifter(45$^{\circ}$-phase step), which is cascaded in series, operated at the center frequency 3 GHz were designed, fabricated and experimented. The measured results were in very close agreement with the corresponding simulation results over the bandwidth of I/O impedance match and phase error for each phase shift.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.9
• /
• pp.2261-2266
• /
• 2009

A novel adaptive phase calibration method is proposed for nonlinear amplifiers. Based on the adaptive process of simple phase vector calculations, the AM/PM distortion can be significantly reduced for various input power. The performance of the proposed method is evaluated for up to 80 % improvements in AM/PM distortions, compared with the distortion of a conventional amplifier. Moreover, by means of an additional envelope-compensation technique, the improvement of the adjacent channel power ratio (ACPR) is presented.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.4
• /
• pp.808-814
• /
• 2007

In this paper, the measurement system of crane moving range is concerned with range recognition technology using phase and magnitude of radio wave. By the proposed technology, we design the radio transmitter and receiver and realize the measurement system, and save the data in disk that is earned from 900Mhz RF signal, middle frequency 450khz of analog signal. As a result of RF measurement, we got 9.3 dBm of RF output and 96 dBc@10khz of phase noise. Range information is earned the data through digital signal processing of IF signal. For the estimation of range measured, we analyze the difference between real range and measurement range, and also suggest the method to remove the measurement error using average processing and amplitude properties. A result is 0.12 and 0.00422 deviation in l0mn-30m and within 5m respectively, and then 2.4E-04 deviation in 4m by using compensation of level characteristics lately.

• Journal of IKEEE
• /
• v.16 no.3
• /
• pp.189-196
• /
• 2012

This paper proposes new phase error compensation method of RVDT encoder in the FFT domain. Phase errors are measured with a small combination of compensation resistors and the changes of first order coefficients of FFT for each resistor are obtained. It is found that the coefficient change is inversely proportional to the inserted resistor. The proposed method takes less time and the size of the table is smaller than previous time domain approaches. In addition, the location of the compensation resistor can be found through axis transformation of the coefficients. Finally, the peak-to-peak phase error was improved to 0.57 which is two times better than previous one.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.1587-1588
• /
• 2015

일반적으로 국내의 대부분의 전기철도는 단상 교류식이므로 전력계통의 3상 154[kV]을 스코트 변압기를 통해 단상 55[kV]로 변환하여 단상 교류로 공급받는다. 전기철도는 기동 특성 및 제동 특성에 따라 부하의 급증과 급감, 임의의 한 급전 구간 내에 운행 일정 중복으로 다수의 전기철도 차량이 운행될 경우 상호간 전기적 특성이 수시로 변한다. 이와 같은 전기적 특성이 수시로 변하는 전력량은 스코트 변압기에서 전력량을 측정하게 된다. 스코트 변압기 1차측 3상 전력이 2차측 단상 전력으로 변환하는 전기기기이며, 전동차가 제동시 회생전력이 발생되는데 이로인해 스코트변압기의 1차측과 2차측 위상이 다르게 발생되어 계량오차가 발생되는 문제점이 있다. 따라서, 본 논문에서는 계량오차의 문제점을 해결하기 위해, 스코트 변압기 2차측 기준으로 전압과 전류의 위상차를 계산하여 회생전력과 수전전력을 정확하게 계량하여 오차를 판단하고 보정하는 알고리즘을 제시하고자 한다.