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나선필,박철순,장원,Nah, Sun-Phil,Park, Cheol-Sun,Jang, Won 한국군사과학기술학회 2005 한국군사과학기술학회지 Vol.8 No.4
In this paper, we propose a new listen-in technique to overcome the problems and the shortcomings which could possibly meet in the previous listen-in methods to deal with the blind signal manually according to operator's decision. In the proposed listen-in method, receiving the signals, classifying the modulation types, and demodulating the signals can be done automatically without operator's intervention. We realize the listen-in technology by developing the high speed frequency tuner, the automatic modulation recognizer, and the signal demodulator. In conclusion, we confirm and show that the developed equipment has a good performance in classifying the modulation type through the computer simulation and the field test.
A Design and Performance Analysis of the Fast Scan Digital-IF FFT Receiver for Spectrum Monitoring
최준호,나선필,박철순,양종원,박영미,Choi, Jun-Ho,Nah, Sun-Phil,Park, Cheol-Sun,Yang, Jong-Won,Park, Young-Mi The Korea Institute of Military Science and Techno 2006 한국군사과학기술학회지 Vol.9 No.3
A fast scan digital-IF FFT receiver at the radio communication band is presented for spectrum monitoring applications. It is composed of three parts: RF front-end, fast LO board, and signal processing board. It has about 19GHz/s scan rate, multi frequency resolution from 10kHz to 2.5kHz, and high sensitivity of below -99dBm. The design and performance analysis of the digital-IF FFT receiver are presented.
Fast Automatic Modulation Classification by MDC and kNNC
박철순,양종원,나선필,장원,Park, Cheol-Sun,Yang, Jong-Won,Nah, Sun-Phil,Jang, Won The Korea Institute of Military Science and Techno 2007 한국군사과학기술학회지 Vol.10 No.4
This paper discusses the fast modulation classifiers capable of classifying both analog and digital modulation signals in wireless communications applications. A total of 7 statistical signal features are extracted and used to classify 9 modulated signals. In this paper, we investigate the performance of the two types of fast modulation classifiers (i.e. 2 nearest neighbor classifiers and 2 minimum distance classifiers) and compare the performance of these classifiers with that of the state of the art for the existing classification methods such as SVM Classifier. Computer simulations indicate good performance on an AWGN channel, even at low signal-to-noise ratios, in case of minimum distance classifiers (MDC for short) and k nearest neighbor classifiers (kNNC for short). Besides a good performance, these type classifiers are considered as ideal candidate to adapt real-time software radio because of their fast modulation classification capability.
박철순(Cheol-Sun Park),나선필(Sun-Phil Nah),양종원(Jong-Won Yang),최준호(Jun-Ho Choi) 대한전자공학회 2008 電子工學會論文誌-TC (Telecommunications) Vol.45 No.4
본 논문은 웨이브릿 변환을 이용하여 사전정보 없이 입사하는 디지털 신호의 변조타입 자동식별 방법에 관한 것이다. 변조인식에 사용되는 특징(key features)은 변조타입에 대한 민감도가 우수하고, SNR에 대한 변화가 적은 속성을 가져야 한다. 잡음에 대한 변화가 적은 속성을 가진 웨이브릿 변환 계수에서 변조인식을 위해 4개의 특징(key features)을 선정하였다. 또한 선정된 특징들을 이용하여 총 8종의 디지털변조 신호를 분류하기 위해 시뮬레이션을 수행하였다. 소프트웨어 라디오의 변조인식 모듈 탑재를 고려하여, 3 타입의 변조인식기에 대한 인식 정확도 및 수행시간을 비교 분석하였다. 시뮬레이션 결과 전체 인식시간은 MDC(Minimum Distance Classifier)와 DTC(Decision Tree Classifier)가 빠르게 수행되었고, 인식정확도는 MDC와 SVMC(Support Vector Machine Classifier)가 우수하게 제시되었다. In this paper, we deal with modulation classification method using WT capable of classifying incident digital signals without a priori information. These key features should have good properties of sensitive with modulation types and insensitive with SNR variation. The 4 key features for modulation recognition are selected using WT coefficients, which have the property of insentive to the changing of noise. The numerical simulations for classifying 8 digital modulation types using these features are performed. The numerical simulations of the 3 types (i.e. DTC, MDC, and SVMC) of modulation classifiers are performed the investigation of classification accuracy and execution time to design the modulation classification module in software radio. The simulation result indicated that the execution time of MDC and DTC was best and MDC and SVMC showed good classification performance.
신드롬 기반 BPTC (196,96) 부호의 SISO 복호 및 성능 분석
임제훈(Je-Hun Lim),나선필(Sun-Phil Nah),송영준(Young-Joon Song) 한국정보기술학회 2014 한국정보기술학회논문지 Vol.12 No.11
In this paper, we researched an iterative SISO decoding algorithm for BPTC of DMR system. Block turbo codes, suggested by Pyndiah in 1998, have been used on communication systems, because the time delay for the decoding is less and the construction is simpler than LDPC. In this paper, we used the low complexity SISO decoding algorithm based on syndrome. When a LLR value of the algorithm is calculated, it emerges the an infinity value for some cases. To solve the problem, we set the extrinsic value as an appropriate value obtained by computer simulation. Also, we show that the performance of the BPTC has about 3dB through computer simulation in AWGN channel environment.
채널화 방식을 이용한 저피탐 도약신호 감지 성능에 관한 연구
고민호,서유석,김형주,나선필,Go, Min-Ho,Seo, Yoo-Seok,Kim, Hyoung-Joo,Nah, Sun-Phil 한국전자통신학회 2014 한국전자통신학회 논문지 Vol.9 No.6
본 논문은 짧은 감지 시간과 높은 시간 해상도 특성을 갖는 협대역 채널화 라디오미터의 성능을 이론 수식을 이용하여 검증하였다. 모의실험 결과, 채널화 라디오미터는 광대역 라디오미터에 비해 2.5 dB 우수한 감지성능을 나타내었지만 잡음 영향에 민감한 특성을 갖는다는 것을 확인하였다. 또한 협대역 라디오미터의 신호대잡음비는 도약율과 지터 특성 급격한 특성 변화를 갖으며, 두 파라미터에 의해 선형적인 성능 저하를 나타내었다. In this paper, the performance of the narrowband channelized radiometer that have a short detection time and high time-resolution was verified based on the theoretical formula. According to the simulation result, the channelized radiometer showed 2.5 dB superior detection performance compared to the broadband radiometer, but is more sensitive to the effects of noise than the broadband radiometer. Also the signal-to-noise of a channelized radiometer was changed dramatically according to the hop rate and jitter effect, which is linearly decreased as the change of two parameters.