• 한국정보통신학회논문지
• /
• 제9권8호
• /
• pp.1780-1786
• /
• 2005

디지털 신호의 전송 성능은 전송 시스템의 위상 에러에 지배적으로 영향을 받고 있으며, 위상 에러는 랜덤 특성을 갖는 위상 잡음과 도플러에 의한 추적 위상 에러에 의해 발생된다. 도플러 현상이 나타나는 움직임을 갖는 이동형 위성통신 시스템에서는 랜덤 위상 잡음과 추적 위상 오차에 의한 전송 신호의 영향을 해석하여 이동형 위성통신 시스템에 적합한 시스템 요구 위상 잡음 스펙트럼을 설계해야 한다. 본 논문에서는 이동형 양방향 위성통신 시스템의 비대칭 이동 서비스에 대한 도플러 영향과 위상 에러를 해석하여 요구되는 전송 시스템의 위상 잡음 스펙트럼을 설계하고, 움직임을 갖는 단말국의 도플러 영향을 최소화하는 전송서비스를 해석한다. 제안한 위상 잡음 스펙트럼은 요구 전송 시스템에 대한 주파수 발생 부 주파수 특성으로 설계할 수 있다.

• Journal of the Optical Society of Korea
• /
• 제15권3호
• /
• pp.244-251
• /
• 2011

We propose a new 2-step phase-shifting digital holographic optical encryption technique and analyze tolerance error for this cipher system. 2-step phase-shifting digital holograms are acquired by moving the PZT mirror with phase step of 0 or ${\pi}$/2 in the reference beam path of the Mach-Zehnder type interferometer. Digital hologram with the encrypted information is Fourier transform hologram and is recorded on CCD camera with 256 gray-level quantized intensities. The decryption performance of binary bit data and image data is analyzed by considering error factors. One of the most important errors is quantization error in detecting the digital hologram intensity on CCD. The more the number of quantization error pixels and the variation of gray-level increase, the more the number of error bits increases for decryption. Computer experiments show the results to be carried out encryption and decryption with the proposed method and the graph to analyze the tolerance of the quantization error in the system.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제53권9호
• /
• pp.470-474
• /
• 2004

Both ratio error and phase angle error in voltage transformer(VT) depend on values of burden of VT used. A method of evaluation for linearity of ratio error and phase angle error in VT measurement equipment have been developed using the standard resistance burdens, with negligible AC-DC resistance difference less than $10^-6$. These burden consists of five standard resistors, with nominal resistance of 100 $\Omega$, 1 k$\Omega$, 10 k$\Omega$, 100 k$\Omega$, and 1 M$\Omega$. The developed method has been applied in VT measurement equipment of industry and the validity of the developed method has been verified by showing the consistency of the result of linearity obtained using VT with wide ratio error.

• 한국전기전자재료학회논문지
• /
• 제18권8호
• /
• pp.739-746
• /
• 2005

When we design a binary phase holographic optical low-pass filter (HOLF), the phase difference is generally set to be $\pi$ to optimize the diffraction efficiency. However, the phase difference of real HOLF mostly deviate from $\pi$ by the error in the fabrication process. The deviation causes the (0,0)-th order diffracted beam to increase, which results In raising the diffraction efficiency. To study the effects of the phase error on the performance of HOLF, we calculated the MTF of HOLF for various phase differences. The results show that the phase error of 10 $\%$ makes little change in the filtering characteristics of HOLF. Considering the filtering by lens and CCD, the effects of the phase error becomes much smaller. To confirm it experimentally, we fabricated HOLFs for various phase differences. After installing it in a digital camera, we take picture of test targets and observe the Moire fringes and the resolution. The results agree with our prediction.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제55권3호
• /
• pp.134-141
• /
• 2006

A potential transformer(PT) has ratio error and phase angle error. Precise measurement of the errors of PT can be achieved using high voltage capacitance bridge, high voltage capacitor and low voltage capacitor. The uncertainty for this method is evaluated and found to be $20{\times}10^{-6}$ in both ratio error and phase angle error. The values measured for PT using the method are well consistent with the those measured for same PT in NMIA(National Measurement Institute of Australia) within the corresponding uncertainty.

• 제어로봇시스템학회논문지
• /
• 제12권7호
• /
• pp.658-665
• /
• 2006

RVDT is a transducer that presents rotary phase angle according to the displacement of eccentric rotor such as press machine. However a study on the phase error of RVDT that affects precision is not enough. This paper analyzes RVDT phase error and obtains compensation curves with serial or parallel resistance through simulation. First, error compensation procedure that analyses errors due to the unbalance of reference inductances of each pole and uses parallel resistance as a compensation is proposed. Second, error compensation procedure due to the amplitude unbalance of the sensor driving currents is examined by serial compensation resistance. Experimentally, we got stable RVDT with phase error under $1^{\circ}$ by the proposed method.

• 전기학회논문지P
• /
• 제57권4호
• /
• pp.437-443
• /
• 2008

We have developed an evaluation technique for both ratio error and phase displacement of current transformer (CT) comparator by using the precise standard capacitors and resistors. By applying this technique to equivalent circuit of CT comparator evaluation system, we can obtain the calculated and measured ratio errors (or phase displacements) in the CT comparator. Thus we can evaluate ratio errors and phase displacement of CT comparator by comparing the calculated and measured ratio errors (or phase displacements). The method was applied to CT comparator under test with the ratio errors and phase displacement ranges of $0{\sim}{\pm}10%$ and $0{\sim}{\pm}7.5$ crad, respectively. Finally we have compared the ratio error and phase displacement of the CT comparator obtained in this method with specifications of two companies.

• 한국항행학회논문지
• /
• 제9권2호
• /
• pp.140-146
• /
• 2005

본 논문에서는 HDR-WPAN 시스템에 적합한 주파수 옵셋 보상과 누적 위상오차를 개선할 수 있는 트래킹 알고리즘을 제안하고 이에 대해 분석하였다. 주파수 옵셋 보상 알고리즘은 CAZAC sequence의 자기상관 특성을 이용하여 각 심벌 내 샘플 간 위상오차를 통해 coarse 주파수 옵셋과 fine 주파수 옵셋을 추정하게 된다. 그러나 HDR-WPAN 시스템은 payload에 pilot 심벌이 없기 때문에 payload 길이가 길어질수록 샘플 간 미소 위상오차가 누적되어 수신단의 성상도가 회전하게 된다. 따라서 트래킹 알고리즘을 통해 틀어진 누적 위상오차를 보상해야 한다. 트래킹은 성상도내 들어온 신호가 일정 영역을 벗어나게 되면, 벗어난 만큼의 크기 ${\theta}$을 곱해 누적된 미소 위상오차를 보상하게 된다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제53권3호
• /
• pp.137-142
• /
• 2004

A voltage transformer(VT) used for the estabilishment of high voltage national standard, has generally ratio error and phase angle error. Both errors in VT depend critically on values of external burden of VT used. Both ratio ewer and phase angle error in existence of the external burden is calculated. These calculated values are very well consistent with the experimental result. The principle and the measurement method of VT in our institute are also explained.

• International Journal of Internet, Broadcasting and Communication
• /
• 제13권2호
• /
• pp.76-81
• /
• 2021

This study proposes a method to reduce the phase error of the received signal to detect the object bearing. The phase shift of the received signal occurs due to the multipath of the signal by natural structure or artificial structures. When detecting the direction of the object using radio waves, the phase of the received signal cannot be accurately detected because of the phase bearing error in the object detection direction. The object detection direction estimation depends on the phase difference, antenna installation distance, signal source wavelength, frequency band and bearing angle. This study reduces the error of the phase bearing by using the phase delay of the relative phase difference for the signals incident on the two antennas. Through simulation, we analyzed the object direction detection performance of the proposed method and the existing method. Three targets are detected from the [-15°, 0°, 15°] direction. The existing method detects the target at [-13°, 3°, 17°], and the proposed method detects the at [-15°, 0°, 15°]. As a result of the simulation, the target detection direction of the proposed method is improved by 2 degrees compared to the existing method.