• Journal of the Microelectronics and Packaging Society
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• v.7 no.3
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• pp.19-25
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• 2000

In this paper, we describe RF receiver module for IMT-2000 handset with 5 MHz channel bandwidth. The fabricated RF receiver module consists of Low Noise Amplifier, RF SAW filter, Down-converter, If SAW filter, AGC and PLL Synthesizer. The NF and IIP3 of LNA is 0.8 dB, 3 dBm at 2.14 GHz, conversion gain of down-converter is 10 dB, dynamic range of AGC is 80 dB, and phase noise of PLL is -100 dBc at 100 kHz. The receiver sensitivity is -110 dBm, adjacent channel selectivity is 48 dBm.

• Journal of Broadcast Engineering
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• v.11 no.2 s.31
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• pp.222-228
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• 2006

In this paper, we propose a receive diversity method for orthogonal frequency division multiplexing (OFDM) systems with cochannel interference. In the method, combining is done in the frequency domain by using the subcarrier based maximum ratio combining (MRC) method. For MRC, we exploit the power of cochannel interference as well as the power of channel noise. The accuracy of the power estimate of interference plus noise is enhanced by averaging the initial estimates over the correlated subchannels where the coherency between the subchannel gains comes from the limited delay spread of the channel. Simulation results show that the proposed method yields 2-3.5dB gain of signal to noise ratio compared to the conventional MRC method and less than 1 dB difference to the ideal case.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.1
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• pp.75-80
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• 2005

A new antenna shuffling scheme for double space time transmit diversity is proposed. The proposed method obtains the shuffling pattern directly from the estimated channel by maximizing minimum post-processing signal to noise ratio(SNR), while the conventional method minimizes channel correlation. Since the minimum post-processing SNR is directly related with error performance, the proposed method shows better bit error rate performance than the conventional method. Monte Carlo simulations showed that the proposed scheme has more 3 dB SNR gain than the conventional scheme for 10/sup -3/ bit error rate in spatially correlated fadingcaused by a single cluster model.

• Journal of Aerospace System Engineering
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• v.16 no.3
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• pp.73-83
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• 2022

The purpose of this paper was to identify a method to improve received noise in a specific frequency band, caused by RF radiation signals during aircraft operation. The communication equipment of the aircraft is critical to the performance and safety of the flight mission, as it is responsible for the function of internal and external communications. Noise-free, clean communication quality, as well as transmission and receiving functions have to be implemented. Thus, the cause analysis of the reception noise in a specific frequency band, was analyzed through trouble shooting. The receiving noise due to the RF radiation signal emitted from the subsystem unit inside the aircraft, was improved by shielding with a CAP with electroless nickel plating applied. Additionally, the measurement and verification results of the improvement method are also described.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2005.11a
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• pp.95-98
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• 2005

이 논문에서는 동일채널 간섭이 존재하는 채널 환경에서 OFDM(Orthogonal Frequency Division Multiplexing) 시스템의 수신 다이버시티 결합 방법을 제시한다. 제시된 방법에서는 각 수신 안테나로부터의 수신 신호를 주파수 영역에서 부반송파 단위로 결합하며, 잡음과 간섭 전력을 고려한 MRC(Maximum Ratio Combining)를 적용한다. 잡음과 간섭 전력은 채널의 제한된 지연확산에 기인하는 주파수 대역에서의 상관특성(coherency)을 이용하여 인접한 몇 개의 부채널에 대해 잡음과 간섭 전력의 평균을 취함으로써 더 정확한 추정치를 얻는다. IEEE 802.11a 무선 LAN 규격에서 모의실험 결과 제안방법은 기존 방시에 비해 SNR을 2-4 dB 개선하였으며, 정확하게 SINR을 추정한 경우에 대해 1 dB 이내로 접근하는 결과를 나타내었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.4
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• pp.336-342
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• 2003

In this paper, a new differential detector is introduced, in which a solar cell is used to reduce the low frequency interference from environmental optical noise. The solar cell also supplies electrical power to the detector circuit using the optical noise power. The DC voltage from the solar cell is used as a power supply to the detector, and the AC voltage is used to reduce the optical noise in a photodiode with the differential detection method. The signal to noise ratio was improved by about 20 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.4 s.95
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• pp.410-417
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• 2005

In this paper, optical noise is reduced by a differential detector with a plastic optical fiber bundle in a wireless optical interconnection. A plastic optical fiber bundle divides the received optical signal equally and connects it to two photodiodes. In this configuration two photodiodes effectively detect the optical signal at one point, and the output voltage variation due to the abrupt change of optical noise distribution in space disappears. The signal to noise ratio in a differential detector with a fiber bundle was improved to be $10\;\cal{dB}$ higher than in a single photodiode with an optical filter.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.1
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• pp.67-76
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• 2000

In this paper, a low noise amplifier has been developed, which is operating at L-band i.e., 1525-1575 MHz. By using resistive decoupling circuits, the resistor dissipates undesired signal in low frequency band. By adopting this design method the stability of the LNA is increased and the input impedance matching is improved. The LNA consists of the low noise GaAs FET ATF-10136 and the internally matched VNA-25. The low LNA is fabricated by both the RP circuit and the self-bias circuits in an aluminum housing. As a result, the characteristics of the LNA implemented show more than 32 dB in gain, lower than 0.5 dB in noise figure, 18.6 dBm output gain in 1 dB gain compression point.

• The Journal of the Acoustical Society of Korea
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• v.41 no.5
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• pp.507-517
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• 2022

The PhotoAcoustic Microscopy (PAM) has been proved to be a useful tool for biological and medical applications due to its high spatial and contrast resolution. PAM is based on transmission of laser pulses and reception of PA signals. Since the strength of PA signals is generally low, not only are high-performance optical and acoustic modules required, but high-performance electronics for imaging are also particularly needed for high-quality PAM imaging. Most PAM systems are implemented with a combination of several pieces of equipment commercially available to receive, amplify, enhance, and digitize PA signals. To this end, PAM systems are inevitably bulky and not optimal because general purpose equipment is used. This paper reports a PA signal receiving system recently developed to attain the capability of improved Signal to Noise Ratio (SNR) and Contrast to Noise Ratio (CNR) of PAM images; the main module of this system is a low noise, wideband signal receiver that consists of two low-noise amplifiers, two variable gain amplifiers, analog filters, an Analog to Digital Converter (ADC), and control logic. From phantom imaging experiments, it was found that the developed system can improve SNR by 6.7 dB and CNR by 3 dB, compared to a combination of several pieces of commercially available equipment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.10
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• pp.700-707
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• 2014

In this paper, we propose the noise reduction method by using the eigenfilter in cyclic prefix system based on SNR. To obtain the signal eigenvectors for the eigenfiltering, we propose a method of obtaining the autocorrelation matrix by exploiting the circulant property of the received block which results from the cyclic extension of the OFDM symbol. Since the structures of the transmitter and the receiver are not changed, the proposed method is easy to apply to the conventional OFDM system. To verify the proposed method, we evaluate the persistency of excitation (POE) criterion for the input and demonstrate the effectiveness of the proposed method in the simulation results.