• 한국전자파학회논문지
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• 제21권6호
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• pp.617-626
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• 2010

본 논문에서는 광혼합 방식으로 서브 밀리미터 및 테라헤츠 대역 연속파 신호를 발생시키는 기법 중 가장 널리 사용되는 광반송파가 억제된 양측 대역 발생 방식(Double Sideband-Suppressed Carrier: DSB-SC)을 이용하여 발생된 연속파(Continuous Wave: CW) 신호의 위상 잡음 개선을 위하여 광신호의 편광과 위상 제어 기법을 제안하고 실험적으로 증명하였다. 광신호의 편광 및 위상 제어 기법은 일반적인 DSB-SC 신호와 DSB-SC 신호에 포함된 광반송파와 동일한 파장과 위상차를 가지며, 광반송파의 편광 성분 중 하나의 편광 성분만을 갖도록 편광제어된 광신호를 결합하여 광혼합하는 방법이다. 실험 및 측정 결과, 서브 밀리미터파 대역 CW 신호의 크기는 1.5 dB 증가하였으며, 위상 잡음 특성은 약 3 dB@10 kHz offset frequency 개선됨을 확인하였다. 따라서 본 논문의 결과는 광신호의 위상 및 편광 성분 제어만으로 광반송파를 효과적으로 억제하여 서브 밀리미터 및 테라헤르츠 대역 CW 신호의 특성을 개선함으로써 광혼합 방법을 이용한 밀리미터파 및 테라헤르츠파 대역 CW 신호 발생기의 저가화를 위한 기본적인 데이터로서 활용 가치가 높다.

• Journal of Positioning, Navigation, and Timing
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• 제7권4호
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• pp.217-226
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• 2018

According to the Korea Coast Guard's maritime disaster statistics (Korea Coast Guard 2017, Korean Statistical information Service 2018), an average of 2,140 marine accidents occurred every year for the past 6 years and the number of accidents is increasing every year. Among them, maritime accidents of fishing vessels are the most frequent, and recently accidents involving fishing boat and leisure vessels are rapidly increasing as well. In particular, the number of accidents involving leisure vessels increased to about one-third of the accidents of fishing vessels, and emergency rescue requests are increasing every year accordingly. However, the number of crash accidents involving users of small vessels and marine leisure activities are increasing because of the difficulties of installing navigation equipment and electronic navigation charts. Recently, the demand for precise positioning using mobile devices is increasing in the fields of maritime safety, piloting support, and coastal survey. Although various applications of smart devices provide location-based services for users, the measurement results are discontinuous when using the position coordinates of the National Marine Electronics Association (NMEA) calculated by smartphone. Recently, Google announced that they will provide GPS raw data to developers from Android 7.0 Nougat. As a result, developers have an opportunity to receive precise carrier phase and code measurements to make more accurate positioning according to the performance of Android devices. This study analyzed GPS positioning performance using Android devices, and compared and analyzed the positioning performance at sea with high-performance GPS receivers.

• 한국항행학회논문지
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• 제17권6호
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• pp.593-599
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• 2013

본 논문은 차량 환경에서 GPS 반송파 기반 위치 결정을 위한 반송파 불연속 측정치 검출에 대한 내용을 다룬다. 반송파 기반 위치 결정 방식에 있어서 위치 정확도의 신뢰도를 확보하기 위해서는 반송파 불연속 측정치를 검출해야 한다. 반송파 불연속 측정치를 검출하는 방식에는 여러 연구가 있지만 본 연구에서는 차분된 반송파 측정치와 저가의 관성센서를 이용해 추정한 차분된 반송파의 차이를 모니터링 값으로 설정함으로써 GPS 불연속 측정치를 검출한다. 저가의 불연속 측정치 검출 알고리즘을 개발하는 것을 목표로 설계된 불연속 측정치 검출 성능 만족을 위한 관성센서 성능 범위를 도출한다. 이를 통해 적절한 가격과 성능의 관성센서 선택이 가능하다. 선정된 관성센서가 설계치를 만족하는지를 검증하기 위하여 회전 테이블 실험을 진행하였다. 결과적으로 실험치가 설계된 불연속 측정치 검출 성능을 보수적으로 만족하는 검출 성능을 보였다.

• Journal of electromagnetic engineering and science
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• 제9권2호
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• pp.98-104
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• 2009

An InGaP/GaAs MMIC LC VCO designed with Harmonic Noise Frequency Filtering(HNFF) technique is presented. In this VCO, internal inductance is found to lower the phase noise, based on an analytic understanding of phase noise. This VCO directly drives the on-chip double balanced mixer to convert RF carrier to IF frequency through local oscillator. Furthermore, final power performance is improved by output amplifier. This paper presents the design for a 1.721 GHz enhanced LC VCO, high power double balance mixer, and output amplifier that have been designed to optimize low phase noise and high output power. The presented asymmetric inductance tank(AIT) VCO exhibited a phase noise of -133.96 dBc/Hz at 1 MHz offset and a tuning range from 1.46 GHz to 1.721 GHz. In measurement, on-chip down-converter shows a third-order input intercept point(IIP3) of 12.55 dBm, a third-order output intercept point(OIP3) of 21.45 dBm, an RF return loss of -31 dB, and an IF return loss of -26 dB. The RF-IF isolation is -57 dB. Also, a conversion gain is 8.9 dB through output amplifier. The total on-chip down-converter is implanted in 2.56${\times}$1.07 mm$^2$ of chip area.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.141.5-141
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• 2001

An attitude GPS receiver with 3 antennas obtains 3-dimensional attitude using GPS carrier phase measurement INS obtains the 3 dimensional navigation solution for IMU consisting of accelerometers and gyro. Ground-alignment process for the low -cost INS cannot be performed well due to the large sensor noise. Using the standard GPS receiver, however, continuous in-flight alignment for the INS becomes possible, and consequently, the errors in IMU sensors and navigation solution can be compensated. Especially with attitude measurement from the attitude GPS receiver, the compensation of errors in gyroscope and attitude would be done respite of the vehicle´s dynamics and their error covariance would be reduced. This paper presents ...

• International Journal of Control, Automation, and Systems
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• 제4권3호
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• pp.333-343
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• 2006

In this paper, the baseline-length information is directly modeled as a measurement for the Wald test, which speeds up the resolution convergence of the integer ambiguity of GPS carrier phase measurements. The convergent speed improvement is demonstrated using numerical simulation and real experiments. It is also shown that the integer ambiguities can be resolved using only four actual satellite measurements with very reasonable convergence speed, if the baseline-length information is used just like one additional observable satellite measurement. Finally, it is shown that the improvement of convergence speed of the Wald test is due to the increase of the probability ratio with the use of the baseline-length constraint.

• Journal of Astronomy and Space Sciences
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• 제26권1호
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• pp.59-74
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• 2009

Relative navigation system is presented using GPS measurements from a single-channel global positioning system (GPS) simulator. The objective of this study is to provide the real-time inter-satellite relative positions as well as absolute positions for two formation flying satellites in low earth orbit. To improve the navigation performance, the absolute states are estimated using ion-free GRAPHIC (group and phase ionospheric correction) pseudo-ranges and the relative states are determined using double differential carrier-phase data and singled-differential C/A code data based on the extended Kalman filter and the unscented Kalman filter. Furthermore, pseudo-relative dynamic model and modified relative measurement model are developed. This modified EKF method prevents non-linearity of the measurement model from degrading precision by applying linearization about absolute navigation solutions not about the priori estimates. The LAMBDA method also has been used to improve the relative navigation performance by fixing ambiguities to integers for precise relative navigation. The software-based simulation has been performed and the steady state accuracies of 1 m and 6 mm ($1{\sigma}$ of 3-dimensional difference errors) are achieved for the absolute and relative navigation using EKF for a short baseline leader/follower formation. In addition, the navigation performances are compared for the EKF and the UKF for 10 hours simulation, and relative position errors are mm-level for the two filters showing the similar trends.

• 한국정보통신학회논문지
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• 제20권4호
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• pp.811-818
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• 2016

추가적인 부궤환 루프를 가지는 연속 미세 조절 위상 고정루프를 소개하였다. 위상고정루프가 위상이 고정되지 않았을 때 위상고정루프는 연속적인 밴드 선택 루프를 통하여 빠르게 위상을 고정시키는 특성을 가지고 있다. 위상고정루프가 고정 상태에 다다랐을 때 밴드 폭은 미세한 루프를 통해서 좁아진다. 추가적인 부궤환 루프는 안정성과 위상여유 성능을 향상시킨다. 0.18um CMOS 공정으로 제작한 위상고정루프의 결과 측정은 위상 잡음이 742.8MHz 캐리어 주파수로부터 2MHz 오프셋 주파수에서 -109.6dBc/Hz을 보여준다.

• 한국전자파학회논문지
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• 제11권5호
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• pp.715-722
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• 2000

본 논문에서는 X-band(8 GHz)용 위상고정 유전체 공진 발진기를 설계 및 제작하였다. 직렬 궤환형 구조로 높은 선택도(Q)를 가지고 유전체 공진기와 주파수 동조를 위하여 바랙터 다이오드, loop filter와 10GHz까지 동작하는 prescaler를 이용하여 구성하였으며, 전압제어 발진기의 신호와 수정 발진기의 신호를 위상 검출기에 넣어 두 신호의 위상을 검출.고정함으로써 높은 안정도의 신호원을 얻을 수 있도록 구현하였다. 측정 결과 본 논문의 위상고정 유전체 공진 발진기는 8GHz에서 2.5dBm의 출력과 -26dBc의 고조파 억압과 중심주파수에서 10KHz offset에서 -64.33dBc의 위상잡음을 얻었으며, 전압제어 유전체 공진 발진기에 비하여 높은 주파수 안정도를 가지는 것을 볼 수 있었다.

• Transactions on Electrical and Electronic Materials
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• 제11권1호
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• pp.20-23
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• 2010

The analog front end (AFE) of a radio frequency identification transponder using the ISO 14443 type A standard with a 100% amplitude shift keying (ASK) modulation is proposed in this paper and verified by circuit simulations and measurements. This AFE circuit, using a 13.56 MHz carrier frequency, consists of a rectifier, a modulator, a demodulator, a regulator, a power on reset, and a dynamically enabled digital phase locked loop (DPLL). The DPLL, with a charge pump enable circuit, was used to recover the clock of a 100% modulated ASK signal during the pause period. A high voltage lateral double diffused metal-oxide semiconductor transistor was used to protect the rectifier and the clock recovery circuit from high voltages. The proposed AFE was fabricated using the $0.18\;{\mu}m$ standard CMOS process, with an AFE core size of $350\;{\mu}m\;{\times}\;230\;{\mu}m$. The measurement results show that the DPLL, using a demodulator output signal, generates a constant 1.695 MHz clock during the pause period of the 100% ASK signal.