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A Theoretical Study on Minimum-Bandwidth Line Coding
김대영,강창구,배철,오승협,Kim, Dae-Young,Kang, Chang-Goo,Bae, Cheol,Oh, Seung-Hyeub The Institute of Electronics and Information Engin 1990 전자공학회논문지 Vol.27 No.5
In this paper, some new results on minimum-bandwidth system are presented. First, we state sufficient condition for the existance of a existance of a power spectral null at the zero frequency and Nyquist frequency. Second, eye boundary functions and eyewidth are obtained for minimum-bandwidth systems of arbitrary numbers of transmitted symbol levels. Third, for linear minimum-bandwidth systems usually known as PR systems, we derived formulars for evaluating DSVs and ASVs in terms of the coefficients of the system polynomials and using formulars, we obtain DSVs and ASVs of various PR systems. Last, the relations among DSV, ASV, power spectral nulls, system polynomial nulls, and the minimum-bandwidth property are summarized.
A BER Performance of Analysis and Comparison for Ultra-Narrowband Digital Radio System
정영준(Young-Jun Chong),강민수(Min-Soo Kang),유성진(Sung-Jin You),임동민(Dong-Min Lim),오승협(Seung-Hyeub Oh) 한국전자파학회JEES 2004 Journal of Electromagnetic Engineering and Science Vol.4 No.2
In this paper, we evaluate the performance of the digital modulation schemes described in the APCO Project 25 FDMA specifications which can be used for applying the ultra-narrowband technology to the current domestic simple two-way radio systems, and discuss difficulties in the DSP implementation or the systems. We analyze the effect on the systems' BER performance or receiver non-matched filter and frequency-offset between the transmitter and receiver oscillators. And we present a frequency offset compensation method for improving the system performance.<br/> The results of performance analysis showed that the CQPSK or APCO Project 25 using non-matched filter degraded the BER by 0.5-1.0 dB comparing with PI/4 DQPSK using matched filter. In the event of 2 % frequency offset, about I dB performance loss was produced at the BER of 10-3. With the frequency-offset compensation method implemented in the systems using phase recovery scheme of PSK synchronization detection, the performance degradation or about 1.0 dB was occurred at the BER of 10-³ for 10 % of frequency offset. The proposed method can be used for the improvement or system performance.