• Journal of Navigation and Port Research
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• v.29 no.10 s.106
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• pp.877-882
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• 2005

It is necessary that Fail-Safe Seaway technology providing a continuous navigation solution though fault of navigation system is occurred in sea. This paper focus on signal processing of GPS receiver, one of receivers using the software radio technology to implement a integrated radio navigation system including satellite-based and ground-based navigation systems. It is difficult to implement the software GPS receivers using a commercial processor because of the heavy computational burden for processing the GPS signals in real time. This paper proposes an efficient multi-bit GPS signal processing scheme to reduce the computational burden for processing the GPS signals in the software GPS receiver. The proposed scheme uses a compression concept of the multi-bit replica signals and patterned look-up table method to generate the correlation value between the GPS signals and the replica signals.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.1
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• pp.11-20
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• 2016

In this paper, a system that can collect GPS L1 C/A, GLONASS G1, and BDS B1I signals with single front-end receiver was implemented using a universal software radio peripheral (USRP) and its performance was verified. To acquire the global navigation satellite system signals, hardware was configured using USRP, antenna, external low-noise amplifier, and external oscillator. In addition, a value of optimum local oscillator frequency was selected to sample signals from three systems with L1-band with a low sampling rate as much as possible. The comparison result of C/N0 between the signal collection system using the proposed method and commercial receiver using double front-end showed that the proposed system had 0.7 ~ 0.8dB higher than that of commercial receiver for GPS L1 C/A signals and 1 ~ 2 dB lower than that of commercial receiver for GLONASS G1 and BDS B1I. Through the above results, it was verified that signals collected using the three systems with a single USRP had no significant error with that of commercial receiver. In the future, it is expected that the proposed system will be combined with software-defined radio (SDR) and advanced to a receiver that has a re-configuration channel.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.37-42
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• 2005

It is necessary that Fail-Safe Seaway technology providing a continuous navigation solution though fault of navigation system is occurred in sea. This paper focus on signal processing of GPS receiver, one of receivers using the software radio technology to implement a integrated radio navigation system including satellite-based and ground-based navigation systems. It is difficult to implement the software GPS receivers using a commercial processor bemuse of the heavy computational burden for processing the GPS signals in real time. This paper proposes an efficient multi-bit GPS signal processing scheme to reduce the computational burden for processing the GPS signals in the software GPS receiver. The proposed scheme uses a compression concept of the multi-bit replica signals and patterned look-up table method to generate the correlation value between the GPS signals and the replica signals.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1752-1753
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• 2011

본 연구에서는 K-water에서 수문관측용으로 무궁화 5호 위성을 이용하여 홍수예보망의 원격 데이터 취득하는데 있어서, 효율적인 위성통신망 운영을 위하여 위성 수신신호 분석용 프로그램을 자체 개발하여 모니터링하고 있으며, 이를 통하여 수신신호가 낮은 관측국에 대한 문제점 제시와 해결방안을 모색코자 하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.1113-1114
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• 2015

세계적인 위성항법시스템 중에서 러시아의 GLONASS 시스템은 구소련의 붕괴이후 재정문제로 시스템이 완전한 임무수행 불가능하였으나 최근 러시아 정부의 위성항법 현대화 정책 추진으로 완벽한 상용화 및 추가적인 개선이 이루어지고 있다. 따라서 GLONASS 현황을 분석하고 위성으로부터 실측 데이터를 수신하여 분석한 결과 GPS 위성과 대등한 수준으로 향후 위성항법 사용자 측면에서 GLONASS 이용과 더불어 통합수신기 이용도 고려해야할 것이다.

• Journal of Navigation and Port Research
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• v.43 no.1
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• pp.42-48
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• 2019

The significance of PNT information in the fourth industrial revolution is viewed differently in relation to the past. Autonomous vehicles, autonomous vessels, smart grids, and national infrastructure require sustainable and reliable services in addition to their high precision service. Satellite navigation system, which is the most representative system for providing PNT information, receive signals from satellites outside the earth so signal reception power is low and signal structures for civilian use are open to the public. Therefore, it is vulnerable to intentional and unintentional interference or hacking. Satellite navigation systems, which can easily acquire high performance of PNT information at low cost, require alternatives due to its vulnerability to the hacking. This paper proposed R-Mode (Ranging Mode) technology that utilizes currently operated navigation and communication infrastructure in terms of Signals of OPportunity (SoOP). For this, the Nationwide Differential Global Navigation Satellite System (NDGNSS), which currently gives a service of Medium Frequency (MF) navigation signal broadcasting, was used to validate the feasibility of a backup infrastructure in domestic maritime areas through simulation analysis.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.80-84
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• 2007

In this paper, the introductory study of the multi input multi output (MIMO) techniques for satellite communication systems is presented. Because of the advantage of wide coverage of satellite, it has been considered for broadcasting services and fill-in services. On the other hand, state of the art multi input multi output (MIMO) techniques such as space time code (STC) and spatial multiplexing (SM) makes the terrestrial system increase link performance and their coverage, and also increase the link throughput. For these regard, in order to satisfy the requirements of the next generation communications and coexists with terrestrial systems harmoniously, the studying about satellite MIMO techniques is necessary. In this paper, we introduce some system model and scenarios to apply MIMO technique to intermediate module repeater (IMR). The possibility of these techniques and technical requirements are also considered. Especially, Space time code is used to enhance IMRs coverage and increase the link performance, and space time multiplexing is utilized to multiplex satellite broadcasting signals with local broadcasting signal in IMR cell.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.3
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• pp.433-438
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• 2017

Containing an Angle-of-Arrival(: AOA) estimation and interference suppression techniques, an adaptive beamformer is one of core techniques for the Signal Intelligence(: SIGINT) which collect various intelligence utilizing cutting edge devices including the radar and satellite. It generates a beam with the directivity in a corresponding direction, to efficiently receive a signal from the specific direction, using antenna array. In this paper, we present the received signal model including interference signals and noise, which can be applied to an input of the signal intelligence satellite system equipped with the AOA estimation and the interference cancellation techniques, and analysis the characteristics of various signals, which can be included in the proposed received signal model. This proposed signal model can be directly applied to the performance evaluation for a variety of beamforming techniques. Also, we verify the spectrum characteristic of the presented received signal model in the frequency domain through computer simulation examples.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.12
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• pp.1079-1085
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• 2013

Due to the limited power supply resources, it is essential that the minimization of algorithmic operation and the reduction of the hardware logical-resources in the design of the satellite transponder. It is also required that the transponder process the signals of various bandwidth efficiently, that is suitble for the SDR-based implementation. This paper proposes a variable rate down sampler which can provide variable bandwidth and data rate for carrier, ranging and sub-band command signals respectively. The proposed down sampler can provide multiple $2^M$ decimated outputs from a single half band filter with recursive arithmetic architecture, which can minimize the hardware resources as well as the arithmetic operations. The algorithm for hardware implementation as well as the analysis for the passband flatness and aliasing is presented and varified by the FPGA implementation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.8
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• pp.767-773
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• 2008

Galileo is a new civil Global Navigation Satellite System(GNSS) developed by Europe. GIOVE-A, a satellite to test Galileo system performance, transmits navigation signal on orbit. Evaluation of Galileo system and development of Galileo receiver needs to analyze GIOVE-A signals. In this paper, we received GIOVE-A signals and processed it using GIOVE-A Interface Control Document(ICD). Signal acquisition, tracking and navigation message decoding made grasping current signal status possible. Bandwidth increase by BOC modulation is one of the difference from GPS. Therefore, we investigated feasibility of conventional GPS L1 RF front-end to receive GIOVE-A E1 signal by evaluation of receiving performance of navigation signal on each bandpass filter of RF front-end.