Inone Joo

Bidirectional positioning system for ubiquitous computing

This work presents a bidirectional positioning system (BPS) that provides a physical location bidirectionally between mobile stations for ubiquitous computing. BPS uses a trilateration computation by the time-of-flight of an ultrasonic signal and shares the physical location of mobile stations through a main server. The performance of BPS is confirmed through benchmarking of positioning systems.

S/W based IF signal simulator prototyping for L1 C/A, L2C, and E1(B&C)

GNSS Digitized IF Signal Simulator (GDISS) is being developed by ETRI as a part of development of software- based Test & Evaluation Facility which will provide test and evaluation environment for various software level application and navigation algorithm in GNSS. GDISS will provide digitized IF data of GPS and Galileo signals. In this paper, GDISS prototype for L1, L2C, and E1(B&C) is developed and verified. The proposed prototype has good modularity and flexibility to add conveniently various modelings like ionospheric model, tropospheric model, multipath model, satellite clock model, etc. It will be verified by the commercial S/W receiver, Nordnav, and the S/W receiver implemented by CNU(Chungnam National University).

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.

Satellite TDMA controller design for timing acquisition and timing synchronization

A satellite TDMA controller (STC) design for timing acquisition and timing synchronization in satellite TDMA systems is presented; it utilizes a modified open-loop control method in the acquisition process and a closed-loop control method in the synchronization process. Since the modified open-loop control method affords a wide timing margin, the timing acquisition can be securely established. Besides, the closed-loop control method can maintain stable timing synchronization. The feasibility of STC design is confirmed through experiments.

Design of GNSS jamming propagation simulator using ITU-R P.1546 propagation model

As Location Based Services(LBS) are developing rapidly in the mobile and information technologies, Global Navigation Satellite System (GNSS) including GPS also becomes very important. But, there is critical problem that GNSS signal is very weak and easily damaged by the jamming attack. The GNSS jamming can cause the social confusion by making the GNSS receiver broke down or malfunctioned. The prediction and analysis of the jamming propagation should be needed to prevent and cope with the damage of the jamming. So, we are developing GNSS interference verification platform which simulates a jamming environment and provides the effect by the jamming propagation. In this paper, we present the design of GNSS jamming propagation simulator based on ITU-R P.1546 propagation prediction model. This simulator will provide the analysis of the jamming propagation based on the geographical information and the damage status of the GNSS receiver by the jamming effect in Korea territory.

Galileo return-link experiment using Galileo receiver and simulator

The Galileo satellite of MEOSAR (Medium Earth Orbit Search And Rescue) system will has the function of return link for search and rescue (SAR) service. MCC (Mission Control Center) sends the return-link message via Galileo E1-B signal to EPIRB, PLB or ELT user. Cospas-sarsat considers a beacon response for acknowledgement message and beacon control with the parameter definition of RLM (Return Link Message) SAR data field. We conducted the function test of Galileo/SAR return link with Galileo signal simulator and Galileo Receiver to define the RLM parameters which is still open.

Availability Analysis of COMS Satellite Ground Control System Considering Infant Mortality

The SGCS system availability is highly required to seamlessly control and monitor the GEO satellite, such as the COMS. In general, the infant mortality phase is characterized by an initially high but rapidly decreasing failure rate. This is because of the existence of weak parts in the system, which will cause failure within a short period of operation. So, the SGCS system availability should be analyzed in the infant mortality phase with a high failure separately from the steady state phase. As the mission lifetime the SGCS system is 10 years, the infant mortality phase is assumed to be the first year of 10 years as mission lifetime. As it is considered that the infant hazard rate is normally 4 times higher than the steady state according to Bellcore or Telcordia standard of AT&T, This standard applies to the first year hazard rate of SGCS system. The SGCS system availability is analyzed by the weighted average with the availability in the first year hazard rate and the availability in the steady state. As a result, The operational availability of the SGCS system considering infant mortality is averagely 99.9977%. As this availability is highly enough, SGCS will control and monitor the COMS satellite in the infant mortality phase.

Operational Availability Analysis of Satellite Ground Control System for COMS

This paper analyzes the operational availability of Satellite Ground Control System(SGCS) for COMS. As a multi-mission GEO satellite, COMS will be launched in the year 2008. Major missions of the COMS are satellite communications, ocean and meteorological observation. The operational availability of SGCS is highly required to seamlessly control and monitor the GEO satellite, such as the COMS. In this paper, for achieving the high operational availability of SGCS system, most of the equipment is 1:1 redundant configuration and the dual network is adapted. Moreover, SGCS system is composed of a primary SGCS and a backup SGCS. The total SGCS system including primary SGCS and backup SGCS has 99.999% of operational availability and only about 39.3 seconds of downtime occurs. Therefore, the operational availability of SGCS system is highly enough to control and monitor the COMS satellite.

GNSS jamming propagation prediction simulator based on ITU-R P.1546 model

The reliability of Global Navigation Satellite System (GNSS) has been very important according to an ever-increasing dependency on GNSS in the position, navigation, and timing (PNT) applications. Nevertheless, there is still a distinctive weakness that GNSS signal is easily damaged by the jamming attack. GNSS jamming incident is considered to be an act of provocation that poses a threat to the security of the country and undermines the safety of civil transportation, including aircraft and vessels. Particularly, GNSS jamming can cause serious damage in the safety-critical applications like the civil aircraft or self-driving smart cars. In this paper, we present the GNSS jamming propagation prediction simulator based on ITU-R P.1546 model for estimating the damage of the GNSS jamming. This simulator predicts the jamming propagation strength based on the geographical information of Korean peninsula. The prediction results of our simulator are verified through comparison with those from the Longley-Rice model.

E1 acquisition and tracking of the first four Galileo IOV satellites in Korea

Galileo system is being under the in-orbit validation (IOV) and and its constellation consists of Proto Flight Model (PFM) and Flight Model 2 (FM2) launched in October 2011 and FM3 and FM4 launched in October 2012. The researchers of the NAVIS Centre and the European Space Agency (ESA) have announced the signal tracking of all the four satellites and the first determination of a ground location, respectively. This paper for the first time, presents E1 acquisition and tracking results using our own receiver after receiving the signals of all the four Galileo satellites at the same time, in Korea. The simulation results show that the SW based Galileo E1 receiver of ETRI successfully processes the signals of all the four Galileo satellites.