Cheon Sig Sin

Improved performance of APSK modulation scheme for sattellite system

This paper propose new bit mapping based on amplitude phase shift keying (APSK) modulation with application to satellite broadband communications in the DVB-S2 standard The APSK modulation outperforms classical 16-QAM and 16-PSK over a typical satellite nonlinear channel due to its intrinsic robustness against the High Power Amplifier (HPA) nonlinear characteristics. The proposed bit mapping considers non-linearity of HPA in the APSK modulation and the performance of APSK modulation for the proposed bit mapping has been compared to the conventional bit mapping.

Development and Performance Analysis of the Second Generation 406 MHz EPIRB

COSPAS-SARSAT system which consists of space segment and ground segment provides a distress alert and the position information for a distressed ship or airplane with beacon equipment. Currently, COSPAS-SARSAT system provides the LEOSAR service which is called to the first generation, and the GEOSAR service as the second generation. The GEOSAR service provides position accuracy better than the LEOSAR service because the second generation 406 MHz beacon allows for the encoding of position data in the transmitted 406 MHz message, thus providing for quasi-real time alerts and position information through the GEOSAR service. ETRI developed emergency position indicating radio beacon (EPIRB) as the second generation 406 MHz beacon for use in maritime applications. Design and implementation aspects of the EPIRB developed by ETRI are presented. Also, performance is presented through the experiment.

Channel capacity enhancement scheme for satellite communication system

In this paper, a hierarchical modulation scheme(and also known as embedded, multi-resolution, or asymmetrical constellation scheme) is studied for transmission of multimedia system. A hierarchical modulation scheme is presented to upgrade an existing digital broadcast system by adding more data stream in its transmissions. The hierarchical modulation is composed of a basic constellation, which is the same as in the original system, and a secondary constellation, which carries the additional data for the upgraded system. The upgraded system with the hierarchical modulation is backward compatible (BC mode) in the sense that receivers that have been deployed in the original system can continue receiving data in the basic constellation. Hierarchical receivers can be designed to receive data carried in the secondary constellation, as well as those in the basic constellation. Specifically, we propose general design guidelines for multimedia transmission over AWGN channels with an hierarchical Amplitude Phase Shift-Keying(APSK) constellation.

Adaptive code decision algorithm for real-time software signal generator

In this paper, we proposed adaptive code decision algorithm for real-time signal generation. Until now, we have been tested to verify the performance and functionality of receiver using hardware GNSS signal simulator. But they are very expensive, may not be available for the signals of interest and consequently might not be always suitable for specialized research due to their lack of flexibility. So, recently, we used to software-based signal generator to test GNSS receiver. They offer a total control of all the parameters for simulation and specialized research as such multipath, jamming, spoofing. The adaptive code decision generation algorithm is the method of GNSS signal generation in real time similar to hardware simulator. Generally software signal generator use to code and carrier DCO. This method spends a lot of time to generate the IF signal because they calculated code value that is applied to sample per IF sample. So, we proposed the algorithm that calculate code value per IF sample block in order to reduce the calculation time of code value.

Analysis of Performance of GPS L1 Signal Generator in GPS L1 Signal

In this paper, we compared and analyzed the performance of generated GPS signal by GPS L1 signal generator with Live GPS signal using the U-Blox receiver. Generally GPS Receiver calculates the position of the satellite by using the ephemeris data received from GPS satellites, and calculates the position of the receiver using the pseudorange. GPS satellites, so it is synchronized, it will then transmit the same data at the same time but the pseudorange because the distance between each satellite and receiver is different. However, For the same signal as the GPS provides the receiver, signal generator is required to generate the RF signal that reflects the pseudorange that different are measured to the same signal as the GPS, not the GPS satellites. This paper provides an overview of a device which can generate an L1 GPS signal at the same time as the GPS signal, and compared with Live GPS signal performance verification for this. As a result, we can check that the navigation of the GPS signals generated in synchronization with the GPS signal can be maintained in the same manner as Live GPS, and the relative pseudorange error between channels are kept constant when generating signals of the long.

Implementation of a signal generator to countermeasure the navigation signal interference

This paper presents the implementation scheme and test result of GNSS signal generator on the hardware platform to countermeasure the GNSS signal interference. The signal generator can be helpful for mitigating the GNSS signal interference. It can be proven firstly the function of GPS signal then prove the function by using hardware platform level. To generate the GNSS signal, Doppler frequency, code and carrier phase can be getting from RINEX(Receiver Independent Exchange Format) data which is saved in previously other material. If GPS interference signal can be happened at particular Pseudo Random Number(PRN) of satellites, it can generate the corresponding GPS signal by using signal generator which is implemented on the Hardware platform. This paper presents the conceptual design result and preliminary functional test of GNSS signal generator by using software receiver to test the function of navigation solution.

Analysis of effect of anti-spoofing signal for mitigating to spoofing in GPS L1 signal

In this paper, we introduce the type of spoofing signal and the method of spoofing mitigation. The spoofing has three type: simplistic, intermediate, sophisticated and we will be interested in the intermediate spoofing. The intermediate spoofers synchronize its counterfeit GNSS signals with the current broadcast GNSS signals. So, if the receiver is attacked by a spoofer, it should be able to detect the spoofing signal through the absolute and relative GNSS signal strength, signal strength changing rate, Bound and compare range rates, etc. There are two way to mitigate spoofing signal, elimination of spoofing channel through the signal processing and counterbalance of spoofing signal through the RF phase control. 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 and generated the anti-spoofing signal to mitigate the spoofing signal. The software GPS receiver simulator(SGRS) received the mixed signal the spoofing, anti-spoofing 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 linear according to mitigate to spoofing signal when the anti-spoofing signal is entered. As a result, we can check that navigation solution is changed from abnormal by spoofing signal to normal by anti-spoofing signal.

A Software Receiver Implementation for GPS L1 and Galileo E1 Signal

This paper presents the PC based experimental software receiver which has been recently extended to a high bandwidth multiple frequency LI signal for GPS and El signal software receiver. The presentation briefly touches upon on signal tracking using prototyping hardware antenna, RF-IF section and software baseband section. In this paper, the efficient algorithms are developed about the signal acquisition and tracking parts in order to obtain the accuracy pseudorange. Finally, the pseudorange is calculated through the relative channel delay received through the different satellite of LI frequency band.

Design of the Network Control System for OBS Satellite Communications System

The on-board switching (OBS) satellite system technology have started domestic development to overcome the limitation of the frequency resource and geostationary orbit existing relay type satellite transponder and the required performance of a spot beam, and looked around the configuration and functions of the multi-beam switching satellite communication system. The monitor and control function of the network control system (NCS) maximizes the operation of the OBS satellite transponder, optimizes the status of the satellite system and satellite communication network by monitoring and controlling predefined satellite parameters of the service network using communications satellite transponder. This paper proposes the requirements of the network control functions from ground control station and then presents a design draft of the system in order to maximize the system availability