• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.122-125
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• 1999

The AC-to-DC single-phase PWM rectifier for traction applications using high power semiconductor, IGCT is made and tested. Parallel operation of two PWM converter is adopted for increasing capacity of converters. For reducing harmonics, the harmonic content is eliminated by the phase shift between two converters switching phase. The output voltage control is achieved by interns calculation without detecting the input current. The part of PLL used for controlling power factor is simply implemented by software.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.394-396
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• 2006

When developing a new GPS receiver module, the essential problems are evaluation of reliable algorithms, software debugging, and performance comparison between algorithms to find optimal solution. Most GPS receiver modules nowadays use a correlator to track signals from satellites and an MCU (Micro Controller Unit) to control operations of the entire module. The problem of software evaluation from MCU is very difficult, due to limitation of MCU resources and low ability of interfacing with user. Normally, user has to expense special tool kit for a limiting access to MCU but it is also hard to use. This article introduces an implementation of a GPS receiver test bed using correlator GP2021 interfacing with ISA (Industry Standard Architecture) PC bus. This way can give user complete control and visibility into the operation of the receiver, then user can easily debug program and test algorithms. For this article, the least square method is implemented to test the hardware and software performance.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.2
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• pp.188-193
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• 2010

With GPS being the primary navigation system, Loran use is in steep decline. However, according to the final report of vulnerability assessment of the transportation infrastructure relying on the global positioning system prepared by the John A. Volpe National Transportation Systems Center, there are current attempts to enhance and re-popularize Loran as a GPS backup system through the characteristic of the ground based low frequency navigation system. To advance the Loran system such as Loran-C modernization and eLoran development, research is definitely needed in the field of Loran-C receiver signal processing as well as Loran-C signal design and the technology of a receiver. We have developed a set of Matlab tools, which implement a software Loran-C receiver that performs the receiver's position determination through the following procedure. The procedure consists of receiving the Loran-C signal, cycle selection, calculation of the TDOA and range, and receiver's position determination through the Least Square Method. We experiences the effect of an incorrect cycle selection and various error factors (ECD, ASF, sky wave, CRI, etc.) from the result of the Loran-C signal processing. It is apparent that researches which focus on the elimination and mitigation of various error factors need to be investigated on a software Loran-C receiver. These aspects will be explored in further work through the method such as PLL and Kalman filtering.

• Journal of Satellite, Information and Communications
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• v.7 no.1
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• pp.128-133
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• 2012

In this paper, we analysis the effect of error of code tracking and frequency tracking according to the chip delay of spoofing signal through the simulation. Firstly, we investigate the type of spoofing signal and defense technical of spoofing attack. For simulation, we generated the intermediate spoofing signal using the software GNSS signal generator simulator(SGGS), the intermediate spoofers synchronize its counterfeit GPS signals with the current broadcast GPS signals. The software GPS receiver simulator(SGRS) received the spoofing signal and normal signal from SGGS, and process the signals. In paper, we can check that the DLL and PLL tracking loop error are generated and pseudo-range is changed non-linear according to chip delay of spoofing signal when the spoofing signal is entered. As a result, we can check that navigation solution is incorrectly effected by spoofing signal.

• Journal of Satellite, Information and Communications
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• v.8 no.2
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• pp.29-35
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• 2013

In this paper, we investigate the type and detection methode of spoofing attack, and then analyze the performance of spoofing detection algorithm in GPS L1 signal through the simulation. Generally spoofer is different from the jammer, because the receiver can be operated and not. In case of spoofing the GPS receiver is hard to recognize the spoofing attack and can be operated normally without stopping because the spoofing signal is the mimic GPS signal. To evaluate the performance of spoofing detection algorithm, both the software based spoofing and GPS signal generator and the software based GPS receiver are implemented. In paper, we can check that spoofing signal can affect to the DLL and PLL tracking loop because code delay and doppler frequency of spoofing. The spoofing detection algorithm has been implemented using the pseudorange, signal strength and navigation solution of GPS receiver and proposed algorithm can effectively detect the spoofing signal.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.109-110
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• 2006

The performance of a digital baseband signal processing and data transmission rate depends on the modulation technique. In this paper, We implemented DSP communication system for Underwater acoustic communication using by adaptive BPSK modem technique. In order to implement adaptive modem, we suggested SNR detection block. SNR detection block has the reference SNR value that selects between window filter path and matched filter path. In this paper, suggested system is based on software interface and all Hardware(PLL, modem filter, equalizer etc) is implemented by software, exclusive of DSP, A/D, D/A converter, SDRAM and Flash memory.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.2
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• pp.23-28
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• 2011

Michibiki is the first QZSS satellite, which was launched by a H-IIA rocket departing from the Tanegshima in Japan on 11 September, 2010 and now operated successfully. This paper presents the results obtained from processing of the L1 C/A signal transmitted from the QZSS satellite. The acquisition and tracking are performed by the L1 software receiver implemented by ETRI. The signal processing results show that QZSS L1 C/A signal is normally processed through the tracking loop results of FLL, PLL, and DLL, the EPL correlator output, and the C/No output. Finally, the paper demonstrates that the QZSS satellite could be used in the navigation system together with the GPS satellite in Korea.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.4
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• pp.6-11
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• 2011

Launch of the first Quasi-Zentih Satellite System (QZSS) satellite, dubbed Michibiki, took place September 11, 2010 and technical and application verification of the satellite is being carried out. This paper presents the results obtained from processing of the L5 signal transmitted from the QZSS satellite. The QZSS L5 signal is collected in ETRI, Korea. And then, the acquisition and tracking are performed by the L5 software receiver implemented by ETRI. The tracking loop of FLL, PLL, and DLL, the EPL correlator output, and the C/No output results show that the QZSS L5 signal is normally processed. Finally, the paper demonstrates that the QZSS L5 signal could be used as GPS satellite based augmentation system in Korea as well as Japan.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.332-335
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• 1990

A digital phase-locked loop speed control system of a self-controlled permanent magnet synchronous mortar fed by a voltage source inverter is presented. This paper discribes the hardware and software design of the system. Variable speed control system for self-controlled permanent magnet synchronous motor is proposed. Simulation results demonstrate the validity of proposed methods. This proposed control technique is implemented by using a microprocessor-based system.

• Journal of the Korea Institute of Military Science and Technology
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• v.3 no.2
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• pp.131-139
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• 2000

A design of CPS attitude determination system is described in this paper. The designed system is a low cost high precision 24 channel single frequency GPS(Global Positioning System) receiver which provides a precise absolute heading and pitch (or roll) as well as a position. It uses commercial chip-set and consists of two RF parts, two signal-tracking parts, a processor, memory parts and I/Os. In order to determine precise attitude, accurate carrier phase measurements and an efficient integer ambiguity resolution method are required. To meet these requirements, a PLL (Phase Locked Loops) is designed, and an algorithm called ARCE (Ambiguity Resolution with Constraint Equation) is adopted. The hardware and software structure of the system will be described, and the performance evaluated under various conditions will be presented. The test results will promise that more reliable navigation system be possible because the system provides all navigational information such as position, velocity, time and attitude.