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Performance Analysis of Vector Delay Lock Loop
Deok Won Lim,Hee Won Kang,Dong-Hwan Hwang,Chansik Park,Sang Jeong Lee 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
In this paper, a Vector Delay Lock Loop (VDLL) which is utilizing navigation results to track code signals is designed in a software GPS receiver. And the performance of it is analyzed in a point of tracking accuracy and compared with that of Scalar Delay Lock Loop (SDLL). Moreover the analyzed performance of VDLL is also confirmed by experiments. Finally, the performance of VDLL can be expected for any environments and the loss of lock can be determined by this result.
Performance Analysis of a Vector DLL Based GPS Receiver
Lim, Deok Won,Choi, Heon Ho,Lee, Sang Jeong,Heo, Moon Beom The Institute of Positioning 2012 Journal of Positioning, Navigation, and Timing Vol.1 No.1
For a Global Positioning System (GPS) receiver, it is known that a Vector Delay Locked Loop (DLL) in which the code signals of each satellite are tracked in parallel by using navigation results shows better performance in the aspect of the tracking accuracy and the robustness than that of a Scalar DLL. However, the quantitative analysis and the logical grounds for that performance enhancement of the Vector DLL are not sufficient. This paper, therefore, proposes the structure of the GPS receiver with the Vector DLL and analyzes the performance of it. The tracking and the positioning accuracy of the Vector DLL are theoretically analyzed and confirmed by simulation results. From the simulation results, it can be seen that the tracking and positioning accuracy has been improved about 30% in case that the receiver is static and the positioning is conducted for every Pre-detection Integration Time (PIT) while C/N0 is 45 dB-Hz.
Analysis of the Results for the Operation of a GPS Jammer Localization System
Lim, Deok Won,Chun, Sebum,Heo, Moon Beom The Institute of Positioning 2017 Journal of Positioning, Navigation, and Timing Vol.6 No.1
In this paper, results of a jammer detection and localization system operation are given. The system consists of receiver stations, a central tracking station, and a monitoring station and it was developed by our institute in 2014. Through real-time tests, it is confirmed that the developed system has an ability to estimate the location of interference sources with an accuracy of 50 m (CEP) even they was 10 km away. After verification, this system was installed in Incheon International Airport and operating results are being monitored by the airport and our institute continuously. In this year, there were some events that jamming signals were received from North Korea, so the data were analyzed and given here.
Considerations for Design and Implementation of a RF Emitter Localization System with Array Antennas
Lim, Deok Won,Lim, Soon,Chun, Sebum,Heo, Moon Beom The Institute of Positioning 2016 Journal of Positioning, Navigation, and Timing Vol.5 No.1
In this paper, design and implementation issues for a network-oriented RF emitter localization system with array antenna are discussed. For hardware, the problem of array mismatch and RF/IF channel mismatch are introduced and the calibration schemes for solving those problems are also provided. For software, it is explained how to overcome the drawback of conventional MUltiple Signal Identification and Classification (MUSIC) algorithm in a point of identifying the number of received signals and problems such as Data Association Problem and Ghost Node Problem in regard to multiple emitter localization are presented with some approaches for getting around those problems. Finally, for implementation, a criterion for arranging each of sensors and a requirement for alignment of array antenna' orientation are also given.
Position DOP Analysis for Sensor Placement in the TDOA-based Localization System
Deok Won Lim,Hee Won Kang,Sang Jeong Lee,Dong-Hwan Hwang 대한전기학회 2012 Journal of Electrical Engineering & Technology Vol.7 No.6
A relationship between the sensor placement and the PDOP (Position Dilution of Precision) is derived in the TDOA-based localization system. And the geometric condition of the sensor placement is analyzed in order to get a minimum PDOP based on the derived relationship. Through computer simulations, effect of the sensor placement on the PDOP is observed.
Galileo BOC(1,1) Signal Tracking using GPS/Galileo Software Receiver
Deok Won Lim,Chansik Park,Sang Jeong Lee 한국항해항만학회 2006 한국항해항만학회 학술대회논문집 Vol.2 No.-
In this paper, a design and implementation of GPS/Galileo software receiver is given. As a GPS receiver, it is able to perform every function of receiver such as acquisition, code and carrier tracking, navigation bit extraction, navigation data decoding, pseudorange calculations, and position calculations. A method to acquire and track the Galileo BOC(1,1) signal is also required because the correlation of BOC(1,1) signal has multiple peaks different from that of GPS signal. Therefore, a method to detect the main-peak in correlation function of BOC signal is required to avoid false acquisition. In this paper, very-early, very late correlation is implemented to track the correct main peak. The performance of implemented GPS/Galileo software receiver with BOC(1,1) signal tracking feature is evaluated with GPS/Galileo IF signal generator.
Position DOP Analysis for Sensor Placement in the TDOA-based Localization System
Lim, Deok-Won,Kang, Hee-Won,Lee, Sang-Jeong,Hwang, Dong-Hwan The Korean Institute of Electrical Engineers 2012 Journal of Electrical Engineering & Technology Vol.7 No.6
A relationship between the sensor placement and the PDOP (Position Dilution of Precision) is derived in the TDOA-based localization system. And the geometric condition of the sensor placement is analyzed in order to get a minimum PDOP based on the derived relationship. Through computer simulations, effect of the sensor placement on the PDOP is observed.
Implementation of Mobile AGPS Receiver with a Modified Acquisition Scheme
Deok Won Lim,Deuk Jae Cho,Chansik Park,Sang Jeong Lee 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7
Because of extremely weak signal level, GPS navigation solution for mobile users is likely to be susceptible to RF sensitivity and multi-path signals, and most GPS receivers are not able to acquire the signal in indoors. Assisted GPS receiver with RF sensitivity enhancement scheme is needed to increase availability for mobile users. AGPS acquisition architecture for RF sensitivity enhancement usually adopts not only the coherent integration technique but also the non-coherent integration technique. A non-coherent integration technique, however, induces the squaring loss for a weak signal, and it is the dominant factor of the acquisition losses in AGPS. The method to reduce the squaring loss had been proposed in recent researches, the implementation and experiments are given in this paper. The performance evaluated by real-time test for weak signal with assistance information from the CDMA network of mobile phone meets the FCC requirements even inside buildings.
Design and Applications of a Generalized Software-Based GNSS IF Signal Generator
Deok Won Lim,Chansik Park,Sang Jeong Lee 한국항해항만학회 2006 한국항해항만학회 학술대회논문집 Vol.2 No.-
In this paper, design and applications of a generalized, versatile and customizable IF signal generator that can model the modernized GPS and Galileo signal is given. It generates IF sampled data that can be directly used by a software receiver. Entire constellation of satellites which is independent of satellite-user geometry is easily determined using a real or simulated ephemeris data. Since the IF center frequency, sampling frequency and quantization bit number are user location dependent parameters, their effects are also considered in IF signal generator. The generalized IF signal generator will be very well suited for the development phase of a software receiver due to its versatility. The full access to the sampling frequency, front-end filter definition and ADC parameters also offers a great opportunity for cost-effective analysis of tracking loops and error mitigation techniques at the receiver level. Interference sources can be easily added to the generator to simulate specific environments. This software IF signal generator can also be used to feed a multi-frequency multi-system software receiver for the prototyping of a combined GPS/Galileo receiver. The test result using the generated signals and a real software receiver shows the effectiveness of the implemented IF signal generator.