Jeom-Hun Lee

Multi-beam Antenna Analysis

This paper describes the antenna analysis of the multi-beam for communication satellite. The design core parameters of the antenna system are optimal antenna diameter, feed horn type and horn size, F/D, and the coordinate of offset horns. The paper deals with the method to determine design core parameters of optimal antenna diameter, feed horn type and horn size. F/D. and the coordinate of offset horns, and the performances of design result

Design of Ka-band Satellite Ground Station Antenna/RF System

This paper describes the design of the Ka-band Antenna/RF system, which was developed for the experiment of the high-speed satellite communications with geostationary satellite. The design issues described here are the ka-band characteristics for having an optimum performance. and the system characteristic for having a reliable and an extensional operation.

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.

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.

Automatic Method for the TC transmission path in COMS SGCS

In this paper, we propose a automatic method of setting up the telecommand (TC) transmission path for stable and seamless TC transmission in COMS (communication ocean meteorological satellite) satellite ground control system (SGCS). The proposed a automatic method uses the command operation procedure (COP) algorithm recommended by the consultative committee for space data system (CCSDS) for guaranteeing a order of TC frame between the ground control system and the satellite and also uses the IF switch to automatically change to a normal TC path by the C&M when a TC path currently transmitted a TC to the satellite is failed. The proposed automatic method is able to more efficiently transmit a TC to the satellite in TC path error than the previous ones

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.

Angular error of LEO tracking system

This paper describes the angular error of the tracking antenna system for LEO (Low Earth Orbit) satellite through the alignment experiment. The purpose of this alignment experiment is to reduce the angular error due to the structural alignment and the monopulse null point alignment error. The angular error that can occur during installation on-site, is the key performance parameter of the tracking antenna system. The angular error is analyzed via a simulation and boresight measurement. The simulation is done with formulas to be derived from vector concept for 3-axis movement. The formulas of the structural alignment are verified by comparing the formula result with the field measurement. Also, the angular error due to monopulse null shift is obtained via boresight measurement. The calibration results for both alignments are described.

Core requirement analysis of GNSS uplink station

The GNSS uplink station is to track the GNSS Satellites in look angle at elevation angle of over 5 deg. by program tracking. Also, during program tracking, the uplink station is to uplink the GNSS mission data, i.e. to receive the data processed in the GNSS control center (GCC) and transmits it to the GNSS satellites. This paper analyzes the key requirement of the uplink station to meet the operation of Galileo satellite tracking and the transmission of uplink signal data from GCC such as frequency and bandwidth. Also this paper deals with other requirement such as wind velocity, and operation conditions.

The Design of TTC Monitoring and Control System in COMS SGCS

[Abstract] In this paper, We designed the control and monitoring(C&M) software in the Communication Ocean and Meteorological Satellite (COMS) Satellite Ground Control System (SGCS) using Component Based Design (CBD). The C&M is the central point to control and monitor the equipment in TTC. It performs continuous monitoring while providing automated and manual control of the equipment in TTC. C&M has the Antenna RF equipment, Modem / BB, Timing equipment which is TTC equipment and communication link through the physical interface such as LAN, RS-232, RS-485. And it has to monitor and has to control each equipment on a real time basis. For C&M design, we extract four Packages with respect to work characteristics and the functions of Packages are following: System Management, Monitoring and Control, Data Management, Data Processing. In this paper, we divided into the physical design side like the C&M hardware configuration and interface and the software design side for C&M function implementation and designed with C&M.

Performance analysis of satellite payload antenna design result

This paper analysis the performance for the design result of the satellite payload antenna, which consists of the parabolic reflector, and multi-feed horns. For the development of the satellite payload antenna design, many steps are needed: antenna geometry design, manufacturing, initial performance test, alignment and performance test, environment test, final performance test and satellite mount test. The antenna geometry design result as the first step of antenna development must be accurate as well as be proposed with the allowable error value to be arisen during the manufacturing, transport, launch, and operation in space environment, because the re-design of antenna electrical design may be difficult during development. Therefore, the design should be verified at electrical design step. This paper describes the verification method of design result and the allowable error during manufacturing, which is restricted by the design