• Journal of Positioning, Navigation, and Timing
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• 제10권4호
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• pp.353-361
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• 2021

This paper presents the jamming effect on the L5 band of Global Navigation Satellite System (GNSS) by analyzing real data collected via measurement campaigns in Korea region. In fact, the L5 band is one of the dedicated bands for various satellite navigation systems such as Global Positioning System (GPS), Galileo, BeiDou (BDS), and Quasi Zenith Satellite System (QZSS). And this band is also allocated along with various systems used for aeronautical radio navigation systems (ARNS). Among ARNS, the Distance Measuring Equipment (DME) and the Tactical Air Navigation System (TACAN) are systems that transmit and receive strong power pulse signals, which may cause unintentional jamming in the reception of GNSS signals. In this paper, signals in the main lobe of GPS L5, Galileo E5a, BDS B2a, and QZSS L5 are collected in Korean region to confirm whether the jamming effect exists in the band. And then, the pulse blanking technique, which is a simple signal processing technique capable of responding to pulsed jamming, is applied to analyze the jamming effect of DME/TACAN on the L5 band.

• Journal of Positioning, Navigation, and Timing
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• 제9권3호
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• pp.273-284
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• 2020

The performance of Global Navigation Satellite System (GNSS) chipset and Inertial Measurement Unit (IMU) sensors embedded in smartphones for location-based services (LBS) is limited due to the economic reasons for their mass production. Therefore, it is necessary to efficiently process the output data of the smartphone's embedded sensors in order to derive the optimum navigation values and, as a previous step, output performance of smartphone embedded sensors needs to be verified. This paper analyzes the navigation performance of such devices by processing the raw measurements data output from smartphones. For this, up-to-dated versions of smartphones provided by Samsung (Galaxy s10e) and Xiaomi (Mi 8) are used in the test experiment to compare their performances and characteristics. The GNSS and IMU data are extracted and saved by using an open market application software (Geo++ RINEX Logger & Mobile MATLAB), and then analyzed in post-processing manner. For GNSS chipset, data is extracted from static environments and verified the position, Carrier-to-Noise (C/N₀), Radio Frequency Interference (RFI) performance. For IMU sensor, the validity of navigation and various location-based-services is predicted by extracting, storing and analyzing data in static and dynamic environments.

• 제어로봇시스템학회논문지
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• 제10권6호
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• pp.529-536
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• 2004

Autonomous navigation of an indoor mobile robot using the global ultrasonic system is presented in this paper. Since the trajectory error of the dead-reckoning navigation grows with time and distance, the autonomous navigation of a mobile robot requires to localize the current position of the robot, so that to compensate the trajectory error. The global ultrasonic system consisting of four ultrasonic generators fixed at a priori known positions in the work space and two receivers on the mobile robot has the similar structure with the well-known satellite GPS(Global Positioning System), and it is useful for the self-localization of an indoor mobile robot. The EKF(Extended Kalman Filter) algorithm for the self-localization is proposed and the autonomous navigation based on the self-localization is verified by experiments.

• Journal of Positioning, Navigation, and Timing
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• 제12권3호
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• pp.229-236
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• 2023

As the importance and dependency of the positioning, navigation, and timing (PNT) information provided by the radio navigation satellite service (RNSS) increases, the vulnerability of RNSS to jamming can lead to significant risks. The signal design under the consideration of anti-jamming performance helps to provide service which is robust to jamming environment. Therefore, it is necessary to evaluate the jamming robustness performance during the design of new signals. In this paper, we introduce figures-of-merit (FoMs) that can be used for an anti-jamming performance analysis of designed signals of interest. We then calculate the FoMs, such as the quality factor (Q factor), tolerable jamming-to-signal ratio (tolerable J/S), and range to jammer (d) for legacy RNSS signals and analyze the results. Finally, based on the results of the analysis, we derive waveform design conditions to obtain good anti-jamming performance. As a result, this paper shows that the waveforms with wide bandwidth leading to good spectral efficiency provide strong anti-jamming performance.

• 전자통신동향분석
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• 제36권4호
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• pp.61-71
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• 2021

Navigation satellite systems (GPS, GLONASS etc.) provide three main services, i.e., positioning for location based services, navigation for multi-modal transportation services, and timing for communication and critical infrastructure services. They were started as military systems but were extended to civil service. Navigation satellite navigation system began with GPS in the USA and GLONASS in Russia at nearly the same time. Indian NavIC and Chines BDS announced their FOCs in 2016 and 2020, respectively and European Galileo and Japanese QZSS are catching up others. In these days, Navigation Satellite System, Positioning, Navigation, and Timing services are part of our daily life very closely. They are required for autonomous driving car, Unmanned vehicles like UAV, UGV, and UMV, 5G/6G telecommunications, world financial system, power system, survey, agriculture, and so on. The services among navigation satellite systems are very competitive and also cooperative one another. This article describes the status of these systems and evolution in the technical and service senses, which may be helpful for planning korea positioning system(KPS).

• 전자통신동향분석
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• 제38권2호
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• pp.12-25
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• 2023

Positioning, navigation, and timing information has become a key element in the national core infrastructure and for emerging technologies, such as autonomous driving, lunar exploration, financial systems, and drones. Therefore, the provision of that information by navigation satellite systems is becoming increasingly important. Existing systems such as GPS (Global Positioning System), GLONASS (GLObal NAvigation Satellite System), and BDS (BeiDou Navigation Satellite System) also provide augmentation, safety-of-life, search & rescue and short message communication and authentication services to increase their competitiveness. Those services and the signals generated for their provision have their own purpose and requirements. This article presents an overview of existing or planned satellite navigation satellite system services and signals, aiming to help understand their current status.

• 전자통신동향분석
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• 제38권3호
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• pp.11-19
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• 2023

Drones, which were early operated by remote control, have evolved to enable autonomous flight by combining various sensors and software tools. In particular, autonomous flight of drones was possible since the application of GNSS-RTK (global navigation satellite system with real-time kinematic positioning), a precision satellite navigation technology. For instance, unmanned drone delivery based on GNSS-RTK data was demonstrated for pizza delivery in Korea for the first time in 2021. However, the vulnerabilities of GNSS-RTK should be overcome for delivery drones to be commercialized. In particular, jamming in the navigation system and low positioning accuracy in urban areas should be addressed. Solving these two problems can lead to stable flight, takeoff, and landing of drones in urban areas, and the corresponding solutions are expected to establish a hybrid positioning technology. We discuss current trends in hybrid positioning technology that can either replace or complement GNSS-RTK for stable drone autonomous flight.

• Journal of Positioning, Navigation, and Timing
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• 제8권4호
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• pp.153-164
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• 2019

This paper presents the development of an end-to-end numerical simulator for signal design of the next generation global navigation satellite system (GNSS). The GNSS services are an essential element of modern human life, becoming a core part of national infra-structure. Several countries are developing or modernizing their own positioning and timing system as their demand, and South Korea is also planning to develop a Korean Positioning System (KPS) based on its own technology, with the aim of operation in 2034. The developed simulator consists of three main units such as a signal generator, a channel unit, and a receiver. The signal generator is constructed based on the actual navigation satellite payload model. For channels, a simple Gaussian channel and land mobile satellite (LMS) multipath channel environments are implemented. A software receiver approach based on a commercial GNSS receiver model is employed. Through the simulator proposed in this paper, it is possible to simulate the entire transceiver chain process from signal generation to receiver processing including channel effect. Finally, numerical simulation results for a simple example scenario is analyzed. The use of the numerical signal simulator in this paper will be ideally suited to design a new navigation signal for the upcoming KPS by reducing the research and development efforts, tremendously.

• 한국산업융합학회 논문집
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• 제26권2_2호
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• pp.359-370
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• 2023

For a vehicle to follow a reference path accurately, its position must be estimated accurately and reliably. In this paper, we propose a lateral control algorithm for autonomous navigation of a vehicle via USAT(Ultrasonic Satellite System), which is an absolute position measurement system using an ultrasonic wave and INS(Inertial Navigation System) integration. In order to estimate the vehicle's parameters, a J-turn test is used. And the autonomous navigation performances of proposed lateral control algorithm and validity of proposed lateral control algorithm are verified and evaluated by simulation and experiments.