• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.8
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• pp.878-887
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• 2012

Aeronautical frequency band is to be internationally protected for aviation safety. Recently, with a rapid growth of an international air traffic, aeronautical frequency band is getting saturated, and thus may causes the interference in the congested frequency band. In this paper, an efficient aeronautical frequency allotment and management policies are proposed for resolving the existing problems in the aeronautical frequency band. The key activities include the review of the aeronautical frequency management and interference mitigation policies in a few important foreign countries such as United States and Japan. This policy study will be contributed for the future air safety in the aeronautical frequency management point of view.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.1
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• pp.80-88
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• 2016

For next generation global navigation satellite systems, new carrier frequencies in Ku/V band are expected to emerge as a promising alternative to the current frequency windows in L band as they get severely congestive. In the case of higher frequency bands, signal attenuation phenomenon through the atmosphere is significantly different from the L band signal propagation. In this paper, a fundamental investigation is carried out to explore the Ku/V band as a candidate frequency band for a new global satellite navigation carrier signal, wherein specific attention is given to the effects of the dominant attenuation factors through the tropospheric propagation path. For a specific application, a candidate orbit preliminarily designed for the Korean regional satellite navigation system is adapted. Simulation results summarize that the Ku band can provide a promising satellite navigation implementation considering the present satellite's power budget, while the V band still requires technical advances in satellite transceiver system implementations.

• Smart Structures and Systems
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• v.1 no.3
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• pp.257-266
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• 2005

In Lamb wave detection of damages in smart structures, the excitation pulse is usually designed as a narrow band burst wave for the convenience of analysis and recognition. However, the wideband excitation can excite more modes in plate/shell structure and thus provides extra information for changes of the structure. This paper presents a method that can extract information in wideband Lamb wave signals. By transforming the detected signals into various sub-frequency band, the measured signal can be converted to its equivalences of narrow band excitations, therefore, the information in different frequency bands can be acquired from a single test and in the same time the complicity of wideband signal can be simplified. Some test results are provided to verify this method.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.5
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• pp.461-466
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• 2012

This paper describes the development and test result of X-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 frequency is used for Telemetry & Command, and X-band frequency is used for mission data. Payload observations data in Mass Memory Unit (MMU) is modulated by QPSK modulator in X-band Transmitter, and then QPSK modulation signal is transmitted to antenna through transfer switch. In this Paper, we described the results of modulation, low-pass filter design, power amp development, and switch test. The FM XTU is delivered Spacecraft Assembly, Integration and Test(AIT) level through the completion of functional Test and environmental(vibration, thermal vacuum) Test successfully.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.3
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• pp.212-217
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• 2016

The S-band receiver for Low Earth Orbit satellite is designed and fabricated as engineering model. Demodulator is implemented by using FPGA for extension of demodulator method. The receiver consists of RF Block, Digital demodulator and Power stage and has a Doppler tracking function to compensate a frequency shift that occur on the operation. The measured results of fabricated receiver show BER of less than $1.0{\times}10^{-6}$ at -110dBm RF input power and equipped a frequency tracking of ${\pm}100KHz$ relative to the center frequency. TID test was satisfied with the results of the test criterion is 10krad.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.1
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• pp.80-86
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• 2010

This paper describes the development result of S-band Transmitter of STSAT-3 by satellite research center(SaTReC), KAIST. STSAT-3 has two kinds of communication channels, S- band for Telemetry & Command and X-band for mission payload. S-band Transmiiter(STX) consist of modulator, frequency synthesizer, power amp and DC/DC converter. The modulation scheme of STX is FSK(Frequency Shift Keying). The interface between spacecraft OBC and STX is RS-422. The STX is based on modular design. The RF output power of STX is 1.5W(31.7dBm) and BER of STX is under 1E-5. The Test of STX is completed successfully such as functional Test and environmental(vibration, thermal vacuum) Test.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.2
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• pp.178-182
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• 2011

A FSK receiver RF block has been developed for Dubaisat-1 Low Earth Orbit satellite. The receiver has Doppler tracking function which compensate frequency shift on uplink channel for commanding the satellite. It consist of LNA, downconverter and IF module. The IF module has Doppler tracking circuitry which sweep and lock on to input signal. It satisfies the requirement of the Dubaisat-1 in mass, power consumption, tracking speed and BER performance.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.12
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• pp.1223-1231
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• 2010

The design is presented for a SATCOM antenna capable of simultaneous multi-band (X/Ku/Ka-Band) communications without replacement of feed horns or change of other parts in the application as a ground satellite terminal for large data transfer. The antenna is the offset configuration and consists of a dual-band(X/Ka-band) feed horn, a single-band(Ku-band) feed horn, a frequency selective surface(FSS) sub-reflector and a parabolic main-reflector. The antenna has a main reflector defining a prime focus and a frequency selective surface sub-reflector defining an image focus. A dual-band feed and a single-band feed are provided at each of the prime focus and image focus. The antenna is designed using 3D EM simulator and the gains measured in X/Ku/Ka-band of the complete antenna assembly is more than 31.6dBi, 36.8dBi, 40.8dBi, and the cross polarization is 21.7dB, 26.6dB, 25.2dB, respectively.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.6
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• pp.609-614
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• 2009

The TT&C communication subsystem of STSAT-3 is consisted of communication link to send telemetry data of spacecraft to the ground station and receive command data from ground station. The S-band receiver is used to receive command data from ground station, Engineering Qualification Model of S-band receiver has been designed and manufactured. The Designed S-band Receiver uses a single conversion for a simple frequency conversion, including a DC-DC Converter and EMI Filter. Also, Digital demodulation part designed using FPGA and RS-422 data interface. The performance of S-band Receiver in functional and space environments test satisfies the requirements of STSAT-3.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.3
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• pp.7-18
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• 2008

Radio systems decline in the system performances when one system is interfered from the other system. System parameters, which are operating frequency, transmit power, and so on, need to be determined in order that there is no interference between radio systems. We investigate the interference from the sound broadcasting service in the band 87.5-108 MHz to the ILS localizer, one of the aeronautical services, in the band of 108-112 MHz. The results are compared with the interference criteria. And then several system parameters, which are frequency, transmit power, and location, are determined in order to avoid the interference from the FM sound broadcasting service which occupies the frequency band near the band of the aeronautical services. The results of this paper can be applied to set up system parameters of the ILS localizer so that system performance can be maximized. Besides, the result of this paper can be applied for determining spectrum management policy.