• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.36-40
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• 2007

EGSE is used to check out satellite payload during the development prior to launch. The EGSE represented in this paper is a test system for Ka band communication transponder of COMS. The EGSE consist of two subsystems as CTS subsystem and PCTS subsystem. Communication Test subsystem (CTS) performs satellite transponder RF performance testing, data analysis and trending. Most of transponder RF performances are automatically tested by the CTS subsystem. Power, Command & Telemetry subsystem (PCTS) monitor telemetry messages from the transponder and send tele-commands to satellite transponder for the configuration change. PCTS also provide simulated S/C power to the transponder during the ground validation testing. The EGSE test functions are verified by the transponder simulator testing and will be used for the flight model transponders testing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10A
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• pp.807-813
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• 2009

A Satellite transponder is the Communication system to process signal with up-link signal recovery, and transmit to ground station through down-link. The orbit flight in the deep space causes high doppler shift in the received signals from the ground station so that the Carrier recovery and fast synchronization system are essential for the transponder system. The conventional analog transponder is employing the system's carrier recovery along with the PLL (Phase Locked Loop) designed for satellite's operation. This paper presents a digital carrier recovery scheme which can provide more reliable and software reconfigurable implementation technique for satellite transponder system without verifying scheme along with transponder designed for short distance or deep space satellite.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.80-89
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• 2010

Transponder is the significant equipment for the telemetry and telecommand operation between the ground station and the satellite. Recently, various transponder technology like Compact Standard Transponder(CST), Small User Transponder(SUT) for data relay satellite, Dual Mode TT&C Transponder(DMT) for large user, and Deep Space Transponder(DST) for deep space mission have been developed according to the communication method and user requirements. Especially, the transponder based on the digital technology comes into the spotlight in the satellite communication field. This paper describes the various analog transponder technology and the state-of-art digital transponder technology grafted onto the existing analog transponder technology.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.312-315
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• 2004

In order to optimize the configurations of Ka-band transponder subsystem, the tradeoff design has been performed iterately with emphasis on the improving performances of the payload system as well as effectiveness of Satellite Communication (SATCOM) system operation. It is necessary to allocate performance to the transponder equipments and to keep providing the main services. It begins with analyzing the requirements and allocating performance parameters by establishing budgets for electrical and mechanical characteristics. In this paper, introduction of SATCOM system and finally optimized Ka-band transponder configuration that is to be used for preliminary design will be mainly presented.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.5
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• pp.842-849
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• 2011

The transponder simulator designed to simulate the transponder of military satellite communication systems in the geostationary orbit is required to have time delay function, because of 250 ms delay time, when a radio wave transmits the distance of 36,000 km in free space. But, it is very difficult to develop 250 ms time delay device in the transponder simulator of 100 MHz bandwidth, due to unstable operation of FPGA, loss of memory data for the high speed rate signal processing. Up to date, bandwidth of the time delay device is limited to 45 MHz bandwidth. To solve this problem, we propose the new time delay techniques up to 100 MHz bandwidth without data loss. Proposed techniques are the low speed down scaling and high speed up scaling methods to read and write the external memory, and the matrix structure design of FPGA memory to treat data as high speed rate. We developed the satellite link simulator in 100 MHz bandwidth using the proposed new time delay techniques, implemented to the transponder simulator and verified the function of 265 ms time delay device in 100 MHz bandwidth.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.7
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• pp.706-712
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• 2004

This paper presents the design technique of output multiplexer(OMUX) for the Ka-band satellite transponder. Output multiplexer consists of low-pass filter(LPF), channel filter and manifold. Channel filters adopt dual-mode technique in design for mass and volume reduction and frequency response of channel filters is 4-pole elliptic response for high frequency selectivity. w-pass filters are designed to be of 13th order corrugated type for high rejection characteristic over reception band of satellite transponder. After initial design of channel filters and manifold, we optimized only a few design parameters for fast and easy optimization instead of optimizing all the design parameter. Measured results of a realized output umltiplexer for Ka-band satellite transponder show good agreement with the computed ones.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.9
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• pp.1167-1176
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• 1995

This paper suggests a method for optimal power assignment of the satellite transponder input carriers in the Multi-level & Multi-bandwidth system. The interference and the noise effects analyzed for the optimal power assignment are intermodulation product caused by the nonlinear transponder characteristics, adjacent channel interference, co-channel interference, and thermal noise in the satellite link. The Fletcher- Powell algorithm is used to determine the optimal input carrier power. The performance criteria for optimal power assignment is classified into 4 categories according to the CNR of destination receiver earth station to meet the requirement for various satellite link environment. We have performed mathematical analysis of objective functions and their derivatives for use in the Fletcher-Powell algorithm, and presented various simulation results based on mathematical analysis. Since the satellite link, it is meaningful to model and analyze these effects in a unified manner and present the method for optimal power assignment of transponder input carriers.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.525-528
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• 2003

This paper describes the effective and rigorous analytic method of multipath effect which results from insufficient isolation characteristics between adjacent channels in communication payload system. It is very important to analyze the multipath effect for verifying the performance of transponder subsystem that especially is consist of multi channels. Finally the multipath effect are analyzed by calculating the GR and GDR for two adjacent channels of Ku-band transponder subsystem on the Communication & Broadcasting Satellite(CBS).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.7
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• pp.594-600
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• 2014

In modern warfare, securing communication channel by combatting opponents' electromagnetic attack is a crucial factor to win the war. Military satellite digital transponder is a communication payload of the next generation military satellite that maintains warfare networks operational in the presence of interfering signals by securely relaying signals between ground terminals. The transponder in this paper is classified as a partial processing transponder which performs cost effective secure relaying in satellite communication links. The control functions of transmission security achieve immunity to hostile interferences which may cause malicious effects on the link. In this paper, we present an efficient architecture for implementing the control mechanism. Two major ideas of pipelined processing in per-group control and software processing of blocked band information dramatically reduce the complexity of the hardware. A control code sequence showing its randomness with uniform distribution is exemplified and qualification test results are briefly presented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.374-379
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• 2001

The satellite electronic equipment is exposed to high level random vibration environment during the launch of spacecraft. The random vibration can cause damage of electronic equipment. Thus very careful consideration on the launch environment, especially for high level random vibration, is required in the design stage of transponder equipments of communication satellite. For the structural integrity of the communication satellite transponder equipment under qualification level random vibration, Finite Element analysis was carried out using the commercial code, MSC/Nastran and ANSYS and stress levels are presented. In order to validate the femodel, modal test was also performed and compared with numerical results.