• Title/Summary/Keyword: $9^{th}$ pulse modulation

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Analysis of LDC Message Reception Performance of Korean eLoran Pilot Service according to Modulation Methods (첨단 지상파항법시스템(eLoran) 시범서비스의 LDC 메시지 변조기법에 따른 수신성능 분석)

  • Pyo-Woong, Son;Sak, Lee;Tae Hyun, Fang;Kiyeol, Seo
    • Journal of Navigation and Port Research
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    • v.46 no.6
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    • pp.525-529
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    • 2022
  • In the eLoran system, the Loran Data Channel (LDC) is used to provide precise timing and positioning. The LDC message can be modulated with the Eurofix method, which modulates the transmission time of the 3rd-8th pulse not used for navigation, and the 9th pulse method, which modulates data using the 9th additional pulse after the existing 8 Loran pulses. In this paper, we analyzed the reception performance of the LDC message transmitted from the eLoran transmitter according to the modulation method. The eLoran testbed transmitter in Incheon was set to transmit LDC messages simultaneously with the 9th pulse modulation method and the Eurofix modulation method. Then, the LDC messages stored in the databases of the eLoran differential stations in Incheon and Pyeongtaek were analyzed in terms of the message reception rate according to the modulation method. Using the navigation aid management ship Inseong No. 1, the range of LDC message reception of actual sea users near Incheon Port was also analyzed. The results of this study are expected to be utilized in the full operational capability service after the eLoran pilot service.

Performance of Double Binary Turbo Code for Ultra Wide-Band Systems with Multiple-Antenna Scheme (다중 안테나 개념을 적용한 초광대역 무선통신 시스템에서 이중 이진 터보 부호 성능)

  • Kim, Eun-Cheol;Cha, Jae-Sang;Lee, Chong-Hoon;Kang, Jeong-Jin;Kim, Seong-Kweon;Hwang, Sung-Ho;Kim, Jin-Young
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.9 no.2
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    • pp.117-122
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    • 2009
  • In this paper, the performance of double binary turbo code is analyzed and simulated in ultra wide-band (UWB) systems employing multiple-antenna scheme. We consider both pulse position modulation-time hopping (PPM-TH) and pulse amplitude modulation-direct sequence (PAM-DS) UWB systems. The space time block code (STBC) scheme is adopted as a transmit diversity method. Also, receive diversity scheme is applied. And double binary turbo code is applied to the UWB system.

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한국 첨단 지상파항법시스템(eLoran) 시범서비스의 LDC 메시지 변조기법 별 수신 성능 분석

  • 손표웅;이삭;황태현;서기열
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2022.11a
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    • pp.204-206
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    • 2022
  • eLoran 시스템에서 보다 높은 정확도로 시각 및 위치 정보를 제공하기 위해 별도의 데이터 채널인 Loran Data Channel (LDC)를 사용한다. LDC 메시지는 기존의 8개의 Loran 펄스 중 항법에 사용하지 않는 3-8번째 펄스의 전송시각을 변조하여 송출하는 Eurofix 방식과 9번째 추가 펄스를 이용해 데이터를 변조하는 9th 펄스 방식으로 변조될 수 있다. 본 논문에서는 eLoran 송신국에서 송출하는 LDC 메시지의 변조방법에 따른 수신 성능을 분석한다. 인천에서 운영 중인 eLoran 시험 송신국에서 9th 펄스 변조방법과 Eurofix 변조방법으로 동시에 LDC 메시지를 송출할 수 있도록 설정하고, 인천과 평택의 eLoran 보정기준국의 데이터베이스 내 저장된 LDC 메시지를 분석해 변조방법에 따른 LDC 메시지 수신률을 분석한다. 또한 항로표지 관리선 인성 1호를 이용해 인천항 인근에서 실제 사용자의 LDC 메시지 수신률을 분석하였다. 본 연구결과는 eLoran 시범서비스 이후 본격적인 서비스 과정에서 중요하게 활용될 것으로 기대된다.

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Elimination of Low Order Harmonics in Multilevel Inverters Using Genetic Algorithm

  • Salehi, Reza;Farokhnia, Naeem;Abedi, Mehrdad;Fathi, Seyed Hamid
    • Journal of Power Electronics
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    • v.11 no.2
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    • pp.132-139
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    • 2011
  • The selective harmonic elimination pulse width modulation (SHEPWM) switching strategy has been applied to multilevel inverters to remove low harmonics. Naturally, the related equations do not have feasible solutions for some operating points associated with the modulation index (M). However, with these infeasible points, minimizing instead of eliminating harmonics is performed. Thus, harmful harmonics such as the $5^{th}$ harmonic still remains in the output waveform. Therefore, it is proposed in this paper to ignore solving the equation associated with the highest order harmonics. A reduction in the eliminated harmonics results in an increase in the degrees of freedom. As a result, the lower order harmonics are eliminated in more operating points. A 9-level inverter is chosen as a case study. The genetic algorithm (GA) for optimization purposes is used. Simulation results verify the proposed method.

Selective Harmonic Elimination for a Single-Phase 13-level TCHB Based Cascaded Multilevel Inverter Using FPGA

  • Halim, Wahidah Abd.;Rahim, Nasrudin Abd.;Azri, Maaspaliza
    • Journal of Power Electronics
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    • v.14 no.3
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    • pp.488-498
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    • 2014
  • This paper presents an implementation of selective harmonic elimination (SHE) modulation for a single-phase 13-level transistor-clamped H-bridge (TCHB) based cascaded multilevel inverter. To determine the optimum switching angle of the SHE equations, the Newton-Raphson method is used in solving the transcendental equation describing the fundamental and harmonic components. The proposed SHE scheme used the relationship between the angles and a sinusoidal reference waveform based on voltage-angle equal criteria. The proposed SHE scheme is evaluated through simulation and experimental results. The digital modulator based-SHE scheme using a field-programmable gate array (FPGA) is described and has been implemented on an Altera DE2 board. The proposed SHE is efficient in eliminating the $3^{rd}$, $5^{th}$, $7^{th}$, $9^{th}$ and $11^{th}$ order harmonics, which validates the analytical results. From the results, it can be seen that the adopted 13-level inverter produces a higher quality with a better harmonic profile and sinusoidal shape of the stepped output waveform.

Exact Bit Error Rate Calculation of UWB-TH PPM Multiple Access Communication systems (UWB-TH PPM 다중 통신시스템의 정확한 비트 오율의 계산)

  • Park, Jang-Woo;Cho, Sung-Eon;Choi, Yong-Suk
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.9 no.6
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    • pp.1174-1181
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    • 2005
  • The exact bit error rate(BER) calculation of an UWB-TH PPM multiple access communication system, which is known to be suitable for the fast transmission of massive information data, is introduced. The statistic feature of the multiple access intereference (MAI) of the system is precisely modeled by the characteristic function technique. The concrete expression for the MAI allows the exact expression for BER to be derived. In addition, we propose the approximate expression for the BER which reveals superior accuracy to the expression from the previous Gaussian approximation of the MAI. The validity of the proposed expressions is confirmed from the comparison of proposed results with the results from Monte-Carlo simulation.

Performance Analysis of Ultra Wideband Impulse Radio System in Partial Band Interference Environment (부분대역 간섭 환경에서 초광대역 임펄스 무선 전송 시스템의 성능 분석)

  • 이양선;강희조;이권현
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.13 no.9
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    • pp.858-864
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    • 2002
  • In this paper, Analyzed Performance of TH/UWB(Time Hopping/Ultra Wideband after Impulse Radio) system in interference environment by existing system that use same frequency band. In case interference fraction ratio is below 0.1, consider and analyzed in case influence through interference in IR system that is shared in 3.1 - 10.6 GHz band hereafter as case that use very small and narrow band than IR system such as 80 MHz bandwidth of ISM band or 802.1la's use bandwidth 20 MHz in 5 GHz band. According to result, we could know that Performance change according to possession band width of interference shows greatly than size of interference electric power. Also, interference fraction ratio is big (more than 0.1) narrowband interference in partial band interference environment, could get Performance improvement of big width increasing pulse repetition number. But, could know that do not influence hardly in system performance when interference fraction ratio is small (below 0.1) narrowband interference. Therefore, may receive the best system performance and transfer efficiency by set the most suitable pulse repetition number according to bandwidth fraction ratio of interference through correct interference fraction ratio estimation and apply proper interference suppression techniques.