• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.1
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• pp.20-25
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• 2012

The COMS, which is a multi-purposed satellite that provide the oceanic measurement data and meterological image data, is operating since 2010. Ka-band satellite communication transponder in COMS gets the MSM function that can provide the required multi-beam and transmits the multi-mode signal with high data rate. The phase noise of COMS communication transponder can be increased because of several local oscillators for MSM function and the utilization of Ka-band frequency. The phase noise affects the performance for the multi-mode and high rate data based- transmission method, it is not possible to recover the transmission data in system with the high system phase noise. In this paper, the phase noise of COMS was measured and the effects of the measured phase noise are analysed and evaluated in the viewpoint of the noise bandwidth of transmission system, Also the transmission performances for multi-mode and high rate data are evaluated in the presence of COMS phase noise.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5A
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• pp.641-650
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• 2000

The effects of noise and doppler for low orbit satellite range measurement using tone method are represented in this paper. Also the optimal noise bandwidth of range signal detection circuit which is used for range measurement system of KOMPSAT is proposed. Based on the effects of satellite orbit parameters via the deduction of dynamic motion characteristics of low orbit satellite and signal to noise spectral density of range measurement signal, the effects of noise and doppler for range measurement system are analyzed. The effect of satellite link noise is decreased, but the effect for doppler is increased as the PLL noise bandwidth of range signal detection circuit is increased. The validation of analyzed effect is verified via comparison of measurement results of KOMPSAT's range measurement system and simulation results in environments of low orbit satellite.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.2 s.332
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• pp.9-16
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• 2005

The performance of satellite range measurement using tone method was analyzed in the presence of satellite link AWGN. The phase errors in range measurement are generated by AWGN of satellite up- and down-link and the degradations of satellite range measurement are dependent on the transmission mode and loop bandwidth of satellite measurement system. The analyzed effects for satellite measurement in presence of satellite link noise were also analyzed with the measured satellite range data via satellite range measurement system operating in satellite link AWGN. In RAU mode, the satellite range differences of 14.4 to 40.6 m were occurred according to the loop bandwidth of satellite range measurement system and the degradation of 0.3 dB compared with theoretical value was generated under condition of the signal-to-noise ratio of 43 dB. In RAU and TM mode, the performances of range measurement were approximately agreed to the that of RAU mode. In order to get the equal performance characteristics with RAU mode, the signal-to-noise ratio of satellite link for RAU and TM mode should be increased by signal power of 2.3 dB, which is a power loss due to transmission of telemetry signal.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.12
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• pp.1207-1215
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• 2008

Satellite generates a complex electromagnetic noise by conducted and radiated coupling effect of the various electrical instruments. This noise may cause serious problems on the satellite system. To minimize the electromagnetic coupling effects and maintain the system safety margin, system noise reduction technique should be applied from the beginning of the system design. The COMS system is evaluated by measuring the conducted noise on system electrical power leads at PSR(Power Supply Regulator) and verifying a 6 dB system safety margin under the complex noise environment with current injection. The radiated noise due to the complex transmit antenna configuration is evaluated by integrating all unit-level RE measurement results, and the RF compatibility between spacecraft and launch vehicle is analyzed with the above estimations. This paper describes the COMS EMC compatibility analysis with respect to each unit level EMC test results, and RF compatibility analysis between spacecraft and launch vehicle. The analyzed results will be reflected on FM(Flight Model) EMC test.

• Journal of Satellite, Information and Communications
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• v.6 no.1
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• pp.45-49
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• 2011

In this paper, we present the high resolution and low phase noise frequency synthesizer for satellite terminal. To improve the phase noise of frequency synthesizer, we analyze how the configuration of frequency synthesizer affect the phase noise. The implemented frequency synthesizer reduce the phase noise and show the high resolution. The output power of this frequency synthesizer is over -2dBm in 950~1450MHz and the phase noise of the -101dBc/Hz at 10kHz frequency offset.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.3
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• pp.485-491
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• 2003

In this paper, We designed the multi-stage amplifier having high gain/low noise characteristics for terrestial repeater of direct digital satellite broadcasting system. In the design the amplifier, we optimized the parameters to have the stable operation between gain, noise figure and stability. The first stage of amplifier can be specified low noise impedance matching, 2nd stage to 5th stage show constant gain and stable operation and final stage of amplifier shows high gain impedance matching. As a result of experiment at the frequency of digital satellite terrestial, show 68dB gain under 2,4dB noise figure and 63dB dynamic range in the 11.7GHz-12.7GHz frequency range, it is a good agreement of communication channel amplifier requirements for satellite terrestial repeater.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.6
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• pp.505-510
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• 2013

In order to detect and identify the GPS clock anomaly in the Differential GPS real environment, this paper addresses a method for minimizing the measurement noise of reference receivers. It estimates the real measurement noise that removed the uncommon error source from pseudorange measurement to minimize the measurement noise. Based on the output of two reference receivers, it first removes the uncommon errors, then optimizes the measurement noise by applying the correction data. Finally, it detects and identifies the satellite clock anomaly using the minimized measurement noise. The method will increase the availability of current DGPS reference system.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.209-212
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• 2002

본 논문에서는 위성방송 수신용 광대역 저잡음 증폭기를 설계 및 구현하였다. 전산모의 실험용 소프트웨어를 사용하여 저잡음 증폭기를 설계하였고, 제작된 저잡음 증폭기의 전기적 특성을 네트워크 분석기와 Noise Figure 분석기를 사용하여 측정하였다. LNA단의 Noise Figure에 중점을 두고 샘플을 제작하여 측정한 길과 전산모의실험에서 나온 데이터는 0.46㏈이하였고 전체 시스템에서 측정된 Noise figure는 0.6㏈정도의 좋은 길과를 나타내었지만, 반면에 이득과 반사손실의 결과가 약간 떨어짐을 보였다 위성 인터넷 등 위성을 이용하는 통신 인구의 급격한 증가와 더불어 구현된 저잡음 증폭기를 사용한 LNB(Low Noise Block down converter)가 널리 응용될 것으로 기대된다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.4
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• pp.59-64
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• 2020

Occasionally, MODEM test in satellite communication systems are needed. But Rx terminals in satellite communications are designed to obtain high SNR generally, therefore artificial bad conditions and environments are demanded for the test. One of the typical method is satellite output power reduction. Using noise generator can be another method. However, these costs a lot of money, time, and procedures in reality. In order to overcome these problems, this paper proposes an artificial noise generation method for MODEM test in satellite communication systems. First of all, SNR of a general heterodyne Rx terminal is calculated. Based on the calculation, a new model which is including variable attenuator is proposed to increase noise level. Simulation results illustrate the variable attenuator can control SNR, and these show that MODEM test in satellite communication systems be possible.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.499-501
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• 2011

The phase noise spectrum distribution of COMS Communication transponder was measured and analyzed in the view point of transmission scheme. The effects of phase noise are also analyzed according to the transmission methods. The phase noise of COMS communication transponder may be increased because of utilization of ka-band. So the effects of phase noise will be increased in conditions of high-order transmission mode. The phase noise characteritics are measured for COMS communication transponder with MSM function and the effects for phase noise are analyzed in this paper.