• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.395-398
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• 2006

In this paper, for implementing a real-time software GNSS receiver we propose the highly efficient and fast algorithms such as partial down-conversion, phase rotator, composite I&Q accumulation, Virtual DCO technique, and parallel acquisition using FFT. When the proposed algorithms are used, more 30 tracking channels with 3 tracking arm(early-prompt-late) is operated real-time on Intel 2.8GHz personal computer. Also, the partial down-conversion reduces the FFT size, for parallel acquisition, to 1/8 of conventional FFT-size and the program size includes map is not exceed 1Mbyte. Finally, the proposed real-time software GNSS receiver using the proposed algorithms provides the navigation solution with below 10 meter rms error.

• Journal of Positioning, Navigation, and Timing
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• 제7권3호
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• pp.113-125
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• 2018

Since the global positioning system receivers on the surface of the Earth use satellite signals sent from a remote distance and the intensity of received signals is weak, they are vulnerable to jamming. This paper implements a vector-tracking loop (VTL)-based global navigation satellite system (GNSS) receiver algorithm as an anti-jamming technique and compares the performance of VTL-based receivers with that of scalar-tracking loop (STL) that is used in general GNSS receivers at various jamming environments and a vehicle's dynamics. The simulation results shows that VTL is more robust against jamming than STL in all operating environments.

• 대한기계학회논문집B
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• 제36권12호
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• pp.1177-1183
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• 2012

본 연구의 목적은 형상계수와 태양추적장치를 이용하여 헬리오스타트에서 흡수기로 복사열전달이 최대화 될 수 있는 시스템을 개발하는 것이다. 헬리오스타트에서 타워 상단에 위치한 흡수기로의 열전달은 대부분 복사에 의해 일어나기 때문에, 복사 열전달에서 사용되는 형상계수를 헬리오스타트 제어에 이용하였다. 태양 추적 및 태양 위치 계산은 CdS 센서와 시뮬링크 프로그램을 이용하였다. 시뮬링크 프로그램을 이용하여 실시간으로 헬리오스타트, 흡수기, 태양 사이의 형상계수가 최대화되는 알고리즘을 적용함으로서, 헬리오스타트에서 흡수기로의 복사 열전달이 최대화 될 수 있도록 하였다. 또한 다양한 조건에 따른 헬리오스타트 제어에 필요한 각을 시뮬레이션 함으로서 각 조건에 필요한 각을 도출할 수 있었다.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2006년도 하계학술대회
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• pp.280-287
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• 2006

Advent of the new European satellite positioning system, Galileo will result in development of new satellite receivers such as, GPS/Galileo dual mode receiver. Furthermore, a new GNSS satellite receiver would be required to be self-reconfigured to certain navigational environments like, indoor, high interference, integrity, etc. In this paper, design and implementation issue of a FPGA based flexible GNSS receiver which gets navigation solution using L1 band signals of GPS and Galileo simultaneously is addressed.

• Journal of Positioning, Navigation, and Timing
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• 제4권1호
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• pp.9-16
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• 2015

The applications of Global Navigation Satellite System (GNSS) receivers are becoming wider in various commercial and military systems including even small weapon systems such as artillery shells. The precision-guided munitions such as Small Diameter Bomb (SDB) of United States can be used for pinpoint strike by acquiring and tracking GNSS signals in high mobility situation. In this paper, a small GNSS receiver with embedded interference suppression capability working under high dynamic stress is developed which is applicable to the various weapon systems and can be used in other several harsh environments. It applies a kind of matched filter and multiple correlator schemes for fast signal acquisition and tracking of even weak signals and frequency domain signal processing method to eliminate the narrowband interference. To evaluate the performance of the developed GNSS receiver, the test scenario of high mobility and interference environment with the GNSS simulator and signal generator is devised. Then, the signal acquisition time, navigation accuracy, sensitivity, and interference suppression performances under high dynamic operation are evaluated. And the comparison test with the commercial GNSS receiver which has high sensitivity is made under the same test condition.

• 한국전자파학회논문지
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• 제17권8호
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• pp.767-772
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• 2006

레이다 기술의 국산화가 이슈가 되고 연구 개발에 박차를 가하고 있는 가운데 본 논문의 Dual-band 모노 펄스 수신기는 추적 레이다를 기반으로 한 실험적 수행 결과를 바탕으로 하고 있다. Dual-band 레이다를 Single-band 레이다와 비교해 보면 높은 비용과 소비 전력 등의 단점을 갖고 있지만 재밍이나 검파 거리, 이미지 신호 제거, 강우 감쇄 특성 면에서 이점을 가질 수 있다. 수신기는 X-band RF head 모듈, Ka-band RF head 모듈, 그리고 공통 IF모듈로 구성되며 X-band와 Ka-band의 각 신호는 IF 모듈의 스위칭에 의해 선택되어진다. 또한 IF모듈의 국부 신호단에서는 위상 제어기가 장착되어 합 채널을 기준으로 고각과 방위각 채널의 위상을 제어할 수 있도록 하였다. 측정 결과 전체 이득은 $40{\pm}3 dB$였으며, 송신/수신간 격리도는 39 dBc, 동적 영역 110 dB, 그리고 잡음지수는 X/Ka-band 각각 4.5dB/6.9dB로 나타났다.

• 한국전자통신학회논문지
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• 제13권1호
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• pp.229-236
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• 2018

본 논문에서는 GPS 수신기에서 L1 C/A 신호의 포착과 추적을 이해하고, GPS 수신기 신호의 수신에 관해서 연구하고, GPS 신호 수신과정에 관해서 Matlab을 사용해서 모의실험을 한다. 실험한 결과, 우리가 실행한 방법의 정확성과 가능성을 확인할 수 있었고, GPS 수신기의 성능은 위성의 수신능력이 매우 중요하다는 것을 알 수 있었다.

• 제어로봇시스템학회논문지
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• 제14권1호
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• pp.7-12
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• 2008

A GNSS(Global Navigation Satellite System) using GPS provides us with very useful information concerning the positioning of users in many sectors such as transportation, social services, the justice system and customs services, public works, search and rescue systems and leisure. A GNSS using the Galileo satellite is due to work in 2008 and expected to be used in various fields such as aviation, marine transportation, land surveying, resources development precise agriculture, telemetics, and so on. In this paper, we discuss the implementation and testing of a combined GPS/Galileo receiver which we named KSTAR V1.0. Each tracking module of GPS/Galileo dual mode correlator has the five track arms which consist of Very Early code, Early code, Prompt code, late code, and Very late code. Each of 24 tracking modules can be assigned to GPS and/or Galileo signal by changing mode selection register. The basic correlator integration dump period is set to 1ms for GPS C/A code and fast Galileo signal tracking. The performance of the developed combined GPS/Galileo receiver was tested and evaluated using the IF (Intermediated Frequency)-level GPS/Galileo signal generator.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.742-745
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• 2009

This paper proposes a wireless LAN antenna system that tracks an object automatically by using image-based tracking. The proposed system consists of a camera and a pan-tilt unit in addition to a directional wireless LAN antenna. The camera and the directional antenna are set in same direction and they are set on the pan-tilt unit. A target object which has a wireless LAN receiver is tracked by using images captured by the camera. And the directional antenna faces in same direction as the camera by the pan-tilt unit. Therefore, the directional antenna keeps pointing the receiver, and a transmitting efficiency is improved. A result of a fundamental experiment shows that a receiver attached to a flying airship was tracked by a prototype of the proposed antenna system. The airship flied about, and the proposed antenna system was set on a roof of a building. The experimental result indicates an effectiveness of the proposed system compared to the conventional directional LAN antenna.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1455-1458
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• 2002

In this paper, we propose a modified CP-AFC(Cross-Product Automatic Frequency Control) algorithm to enhance coherent signal detection for WCDMA reverse link receiver. We introduce a moving average filter at the FDD(Frequency Difference Detector) input to increase the number of cross-products, since pilot symbol in WCDMA is not transmitted continuously. We also add normalization algorithm to overcome the conventional CP-FDD's sensitivity to the variance of input signal amplitude and to increase the linear range of S- curve. For rapid frequency acquisition and tracking, we adopt a multi-stage tracking mode. We applied the proposed algorithm in the implementation of WCDMA base station modem successfully.