• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.6
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• pp.553-558
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• 2011

This paper describes the development and test result of S-band Transmitter flight model(FM) of STSAT-3 by satellite research center(SaTReC), KAIST. The communication sub-system of STSAT-3 is consist of two different frequency band channels, S-band for Telemetry & Command and X-band for mission data. S-band Transmitter(STX) functionally made of modulator, frequency synthesizer, power amp and DC/DC converter. The transmission data is modulated by FSK(Frequency Shift Keying) and the interface between spacecraft sub-module and STX is RS-422 standard method. The FM STX is based on modular design. The RF output power of STX is 1.5W(31.7dBm) and BER of STX is under $1{\times}10^{-5}$ which meets the specification respectively. The FM STX is delivered Spacecraft Assembly, Integration and Test(AIT) level through the completion of functional Test and environmental(vibration, thermal vacuum) Test successfully.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2650-2652
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• 1999

To satisfy the demand for small size, light weight. high density power supply, the switching frequency of DC/DC converters has been increased. The PWM control of the conventional SMPS have a switching frequency that a level of the conducted noise spectra contribute to switching frequency band. So the electronic equipment is not only affected from that but is restricted to internal regulation like CISPR, FCC, and VDE. In this paper, we analyzed Bi-FM. Bi-FM is two fixed switching frequency with a modulation frequency. So emission spectrum of Bi-FM control signal is spreaded and spectral power level is reduced. In this paper, we analyze the spectral analysis of Bi-FM control signal and the spectral comparison between the PWM control and Bi-FM control. And we confirm that reduced the spectrum power level through simulation using Pspice and experiment.

• Journal of the Korean Institute of Telematics and Electronics
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• v.15 no.6
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• pp.29-34
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• 1978

It has been investigated that the elect of an wideband FDM-FM signal upon an M-ary coherent PSK (MCPSK) signal in an intersystem radio interference environment between analog and digital systems, which had not been discussed before and had been obscure. It is assumed that PSK and FM signal are adjacently allocated in same radio frequency band. And the symbol error performance of MCPSK signal with co-channel and adjacent channel interference from an FDM-FM signal is evaluated with considering the receiver noise. The numerical results for the theoretical symbol error rates of MCPSK system in the presence of Gaussian noise and co-channel or adjacent channel interference are given in graphical forms as the function of carrier-to-noise ratio (CNR), carrier-to-interference ratio (CIR) and normalized carrier separation between the desired PSK and interfering FM signal. The objective of this research is to find some optimal conditions for coexistence of analog and digital systems in an intersystem interference environment. The results we obtained here stress a possible utilization of them for designing the frequency allocation, bandwidth and power of PSK channel in the intersystem interference from an FDM-FM signall.

• Journal of Advanced Navigation Technology
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• v.28 no.2
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• pp.193-200
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• 2024

This paper describes the design and development of a transmit receiver module(TRM) for mounting on X-band SAR of the NEXTSat-2. The TRM generates the chirp signal with required bandwidth through the DDS in X-band and performs frequency conversion, combination for the signal to transmit and be received and frequency synthesis. Tx path of the TRM produces signals of total 28 bandwidths up to 96.8 MHz and has output signal level of more than + 9.37 dBm. Rx path of the TRM has minimum noise figure of 15.7 dB. The measurement results show that required requirements are satisfied. The TRM is installed on the NEXTSat-2 flight model(FM), launched by KSLV-II(Nuri) on May 23, 2023 and currently operational.

• BMB Reports
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• v.29 no.5
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• pp.398-404
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• 1996

Light-chilling effects were investigated in chilling-sensitive cucumber (Cucumis sativus L. cv. Ilmichungjang) and chilling-resistant pea (Pisum sativum L. cv. Giant) leaf discs in relation to possible damage in D1 protein. In both plants, dark-chilling did not cause any noticeable changes in (Fv)m/Fm and lincomycin did not affect the decrease in (Fv)m/Fm caused by light-chilling. This result suggests that the de novo synthesis of D1 protein did not occur actively during light-chilling. In pea light-chilled for 6 h. the decreased (Fv)m/Fm was partly recovered in the dark, and almost complete recovery was observed in the light. In cucumber light-chilled for 3 h. the reduced (Fv)m/Fm decreased further for the initial 2 h recovery process in the light regardless of the treatment of lincomycin and recovered very slowly. In both plant species, the treatment of lincomycin inhibited the recovery process in the light, but did not significantly inhibit the process in the dark. In cucumber leaves pulse-labeled with $[^{35}S]Met$, the labeled band intensities of isolated pigment-protein complexes were almost the same during the 6 h light-chilling, but significant decreases in band intensities were observed during the 3 h recovery period. This result suggests that the irreversibly damaged D1 protein was degraded during the recovery period. However, no noticeable changes were observed in the pea leaves during the 12 h chilling and 3 h recovery period. The polyacrylamide gel electrophoresis of the pigment-protein complexes showed that the principal lesion sites of light-chilling were different from those of room temperature photoinhibition.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.911-916
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• 2018

Among the various microwaves, the microwaves that we are using in our life are the things that combined with the information on what we need with various technologies. However, the signals that we do not want to get as an information is just noise. Therefore, we need to collect only the necessary information, and other information needs to be blocked. This technology is called Jamming. In this paper, the Partial-Band Jamming System through the Helical Antenna about target 95.1 and 97.3MHz in 88Mhz to 108MHz of the FM radio frequency band was studied.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.4
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• pp.721-728
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• 1994

In this paper, we analyzed the performances of system considering diversity for FH/CPFSK system with limiter-discrimicator detection and integrate-and-dump post-detection filtering. And, we considered thermal noise and partial-band jamming noise, intersymbol interference for all eight of the possible adjacent bit data patterns, FM noise clicks for evaluation systems. In result, the performance of FH/CPFSK system with diversity under the worst-case partial band jamming noise degraded about 5dB rather than that of without diversity when we considered the thermal noise but improved about 16dB rather than of without diversity when we ignored the thermal noise.

• Journal of Broadcast Engineering
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• v.21 no.5
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• pp.726-738
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• 2016

This study analyzed the properties of VHF band and suggested an efficient VHF band application plan for digital radio and UHDTV broadcasting through the experiment by the house T-DMB device in practical user environment. In order to find an efficient frequency band for digital radio broadcasting, this study examined first, to check the times of drop-out receive occurring in the audible area using a DMB/FM CAR Radio for T-DMB that has the characteristics of DAB. Second, this article explored the phenomenon of feedback loops in the same channel using a T-DMB house gap filler transmitting the signal by the same OFDM modulation scheme with UHDTV for configuring suitable SFN transmission network of the UHDTV broadcasting. Based on these experiments, this study suggested a suitable VHF band for digital radio and an efficient utilization of the VHF frequency band for the SFN network configuration of UHDTV.

• Journal of Broadcast Engineering
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• v.20 no.1
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• pp.122-139
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• 2015

Though the digital transition of terrestrial TV has been completed, the transmission system for terrestrial radio has not been determined and terrestrial radio still keeps its analog transmission. This study, under coorientation model, aims to explore the cognitive difference in recognizing important factors to be considered in deciding the digital radio transmission system between the employees of terrestrial broadcasters and then crucial issues related to the factors are driven. It has been found that the most big cognitive difference among the employees of three major terrestrial broadcasters lies in selecting frequency band for digital radio transmission. But there was little difference of opinion on simultaneous production-transmission, efficiency of frequency usage, broadcast quality and standards of service. The most disputable point in transition to digital radio broadcasting is selecting the frequency band for digital radio between the frequency bands used for FM radio broadcast (88-108MHz), terrestrial DMB (VHF Ch7~13) and FM radio adjacent broadcast band (76~88MHz: VHF Ch5~6). So, the question concludes into the selection issue between DAB+, HD-Radio, and DRM+. To improve the quality of radio broadcasting service and enhance the satisfaction of listeners, it is desirable to allow to operate both production system and transmission station, to enhance high transmission efficiency with minimum transmission facility, and to permit new entrance of broadcasters.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.758-761
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• 2009

It is necessary to estimate the Doppler spectrum for each range cell for the extraction of useful information from the return echoes in radar systems used for the remote sending purpose such as detection of moving targets and weather surveillance. The signal amplitude in the given frequency band is the important parameter in the detection and tracking of targets. However, the system performance can be seriously degraded if the efficient removal of the strong clutter is not possible. If the phase noise spreads both the signal and clutter, the clutter removal can be very difficult and the accuracy of frequency estimates is also deteriorated. Therefore, in this paper, the effects of phase noise are analyzed in the estimation of beat frequencies.