• Journal of the Semiconductor & Display Technology
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• v.18 no.1
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• pp.59-64
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• 2019

Recently, time synchronous has become important for satellite launch control facilities, multiple thermal power plants, and power system facilities. Information from time synchronous at each of these industrial sites requires time synchronization to control or monitor the system with correlation. In this paper, IRIG-B codes, which can be used for time synchronous, are used as specifications in IRIG standard 200-16. Signals from IRIG-B120 (Analog), IRIG-B000 (Digital), and one PPS are output from GPS receiver. Using the signal from IRIG-B120 (Analog), it passes through the signal from the analog amplifier and generates one PPS signal using the field-programmable gate array. The FPGA is used cyclone EPM570T100I5N. According to IEEE regulations, the error of one PPS is specified within 1us, but in this paper, the error is within 100ns. The output of the one PPS signal was then compared and tested against the one PPS signal on the GPS receiver to verify accuracy and reliability. In addition, the proposed time synchronous is simple to construct and structure, easy to implement, and provides high time precision compared to typical time synchronous. The output of the one PPS signals and IRIG-B000 signal will be used in many industry sectors.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.737-738
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• 2011

전력 계통현상 분석장치(DFR)에서 시각동기에 대한 중요성이 부각됨에 따라 장치의 시각동기가 중요하게 대두되고 있다. 본 연구내용에서 보여주고자 하는 DFR TimeSync Simulator는 GPS 수신기로부터 IRIG-B 신호와 1PPS 신호를 수신하여 계통현상 분석장치의 사고발생 이벤트를 위한 절대시각을 제공하는 장치이다. 이 절대시각은 계통현상 분석장치의 정밀성 및 품질을 검증하는데 적용한다. 그리고 개발된 Simulator가 정확한 1PPS 신호를 산출해 내는지를 검증하기 위해 GPS 수신기의 1PPS 신호와 Simulator에서 출력되는 1PPS 신호의 파형을 비교 실험하여 정확도 및 신뢰성을 확인하였다.

• Journal of Power System Engineering
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• v.14 no.1
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• pp.5-10
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• 2010

Both the accuracy and stability of the clock get from the GPS receiver are considered in the range of pps. And we verified the system clock stability of a micro-controller system using the pps pulse supplied by the GPS receiver. In complex system of digital processing, the rack of precise timing signal may cause the serious problem or breakdown accident. To get rid of these undesirable problems, we introduced VCXO circuit to a micro-controller system to preserve high accurate clock stability.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.367-370
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• 2006

A GPS-based time synchronization technique employing a refined HW circuitry and SW algorithm is considered as fine time-management system for Low Earth Orbit (LEO) remote sensing satellites. By synchronizing the On-Board Time (OBT) within satellites to the GPS 1PPS, a very expensive, highly accurate on-board clock is not required to determine the precise on-board time management. Also, the satellite command generation in ground stations and postprocessing of earth observation data which a particular image is acquired. This paper analyses on-orbit verification of the existing satellite time sync architecture and presents a new time sync architecture, operation and relation between the OBT and the GPS time.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2623-2626
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• 2003

GPS provides two services which include SPS(Standard Positioning Service) and PPS(Precise Positioning Service). While SPS users can navigate in more precise due to cancellation of SA(Selective Availability), SPS users has still less precision navigation than PPS users. L1/L2CS integrated receiver can provide more precise navigation to SPS users because the delay of Ionosphere will be cancelled by using two frequencies (L1 and L2). This paper designs an integrated L1/L2CS digital correlator to prepare the L2C signal that will be provided in 2003. Also L2CS transmitter is designed to confirm L2CS correlator.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.1
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• pp.43-48
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• 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.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.5
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• pp.104-108
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• 2004

The most of the CDMA mobile communication depends on the GPS for the time synchronization. Then, we must prepare alternative system against the unusable GPS like a unexpectable accident or strategic purpose by the USA government. In this study, we have constructed ground test segment for the time synchronization system using the geostationary satellite. In addition. we have designed, manufactured and tested the transmitting and receiving board to receive 1 PPS signal from atomic clock for transmitting stored data in buffer to satellite modem and to produce 1 PPS signal from satellite modem for measuring time delay.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.2
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• pp.141-154
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• 2013

The technology of precise time-synchronization between signal receive devices for separation distance operation can be a key point for the technology with TDoA-based system. We propose a new method for the higher accuracy of system's time-synchronization in this paper, which uses OCXO and DPLL with high accuracy to achieve phase synchronization at 1 pps (pulse per second) of signal. And the method receive time value from a GPS satellite. Essentially, the performance of GPS with high accuracy refers to long-term frequency stability for its reliability. As per the characteristic, as the GPS timing signals are synchronized continuously, the accuracy of time-synchronization gets improved proportionally. Therefore, if the time synchronization is accomplished, the accuracy of the synchronization can be up to 0.001 ppb (part per billion). Through the improved accuracy of the time-synchronization, the measurement error of TDOA-based location detection technology is evaluated. Consequently, we verify that TDoA-based location measurement error can be greatly improved via using the improved method for time-synchronization error.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.8
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• pp.789-797
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• 2006

A new method for the GPS repeater based indoor positioning is proposed and its feasibility is verified by experiments in previous paper. But the problems how can identify switching GPS repeater's ID and when switching will be occurred are remained. To solve the problem faced with, we propose the time synchronized switching GPS repeater and the methods of the detection of switching time and the estimation of TDOA. First, switching GPS repeater retransmits the signals synchronized on GPS time, sequentially. Always, first switching time is synchronized with 1 PPS. Second, we formulate the detection of switching time and the estimation of TDOA and propose the various methods. No method is existed absolutely superior to others in any conditions but the method is existed superior to others in specific condition. Finally, feasibility of indoor positioning using time-synchronized switching GPS repeater is evaluated through experiments in anechoic chamber and general environment with multipath.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.82.3-82
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• 2002

This paper designs an integrated navigation system that uses the signals from both GPS satellites and pseudolites. While GPS satellite clocks are synchronized, pseudolite clocks are not exactly synchronized even though pseudolite can use 1PPS signal from the GPS receiver. This can cause large range error and can be solved by transmitting the correction information. Assuming that the positions of pseudolites are known, it is possible to determine the true range between two pseudolites. Also, from the measurement of pseudolite signals, the pseudo range between two pseudolites can be calculated. Using the difference between the true range and the pseudo range, each pesudolite can produce correc...