Improving the Structure of a Signal Used for Real-Time Calibrating of the Receiving Channels of Digital Transceiver Modules in Digital Phased Antenna Arrays

Introduction. Modern digital phased array antenna (DPAA) systems incorporate a large number of identical transceiver modules (TMs). These modules require real-time calibration with a high level of accuracy. In a previous work, we proposed a real-time calibration method for all receiver channels, which is based on the use of a calibration signal (CalSig) of the same frequency spectrum as the reflected signal and modulated in phase and amplitude by BPSK and OOK codes, respectively. This method was found to have a number of advantages over conventional approaches. However, the use of the same CalSig sample for all receiving channels increases the noise power gain at the output of a digital beam-forming unit (DBU). To overcome this limitation, we set out to improve the structure of CalSigs by making them pseudo-orthogonal. As a result, the noise power gain at the DBU output can be significantly reduced compared to that obtained in our previous work.Aim. To propose an improved design of a controlled amplitude modulation code OOK generator, which allows creation of pseudo-orthogonal CalSigs. As a result, the noise power gain at the output will increase insignificantly, thus having no negative effect on the quality of digital beam forming, signal processing and calibration.Materials and methods. Theory of system engineering and technology; theory of digital signal processing; system analysis; mathematical modeling.Results. An improved CalSig for calibrating the receiving channels of TMs was obtained. A structural diagram allowing the formation of pseudo-orthogonal CalSigs was synthesized.Conclusions. We proposed a new approach to improving the structure of signals used for real-time calibrating the DPAA receiving channels. A structural diagram of an amplitude-modulated OOK code generator for pseudo-orthogonal CalSigs was developed.Introduction. Modern digital phased array antenna (DPAA) systems incorporate a large number of identical transceiver modules (TMs). These modules require real-time calibration with a high level of accuracy. In a previous work, we proposed a real-time calibration method for all receiver channels, which is based on the use of a calibration signal (CalSig) of the same frequency spectrum as the reflected signal and modulated in phase and amplitude by BPSK and OOK codes, respectively. This method was found to have a number of advantages over conventional approaches. However, the use of the same CalSig sample for all receiving channels increases the noise power gain at the output of a digital beam-forming unit (DBU). To overcome this limitation, we set out to improve the structure of CalSigs by making them pseudo-orthogonal. As a result, the noise power gain at the DBU output can be significantly reduced compared to that obtained in our previous work.Aim. To propose an improved design of a controlled amplitude modulation code OOK generator, which allows creation of pseudo-orthogonal CalSigs. As a result, the noise power gain at the output will increase insignificantly, thus having no negative effect on the quality of digital beam forming, signal processing and calibration.Materials and methods. Theory of system engineering and technology; theory of digital signal processing; system analysis; mathematical modeling.Results. An improved CalSig for calibrating the receiving channels of TMs was obtained. A structural diagram allowing the formation of pseudo-orthogonal CalSigs was synthesized.Conclusions. We proposed a new approach to improving the structure of signals used for real-time calibrating the DPAA receiving channels. A structural diagram of an amplitude-modulated OOK code generator for pseudo-orthogonal CalSigs was developed

Klein tunneling degradation and enhanced Fabry-P\'erot interference in graphene/h-BN moir\'e-superlattice devices

Hexagonal boron-nitride (h-BN) provides an ideal substrate for supporting graphene devices to achieve fascinating transport properties, such as Klein tunneling, electron optics and other novel quantum transport phenomena. However, depositing graphene on h-BN creates moir\'e superlattices, whose electronic properties can be significantly manipulated by controlling the lattice alignment between layers. In this work, the effects of these moir\'e structures on the transport properties of graphene are investigated using atomistic simulations. At large misalignment angles (leading to small moir\'e cells), the transport properties (most remarkably, Klein tunneling) of pristine graphene devices are conserved. On the other hand, in the nearly aligned cases, the moir\'e interaction induces stronger effects, significantly affecting electron transport in graphene. In particular, Klein tunneling is significantly degraded. In contrast, strong Fabry-P\'erot interference (accordingly, strong quantum confinement) effects and non-linear I-V characteristics are observed. P-N interface smoothness engineering is also considered, suggesting as a potential way to improve these transport features in graphene/h-BN devices.Comment: 21 pages, 8 figures, Supplementary material

AISによる予定航路情報と航海情報に基づく自律的交通管理に関する研究

東京海洋大学博士学位論文 平成19年度(2007) 応用環境システム学 課程博士 甲第84号指導教員: 大津皓平全文公表年月日: 2011-11-22東京海洋大学200

The Relationship between Organizational Culture, Job Satisfaction, and Commitment of Lecturers at Universities

Purpose: The study aimed to determine the influence of factors on job satisfaction and the relationship between satisfaction, organizational culture, and the organizational commitment of lecturers at universities in Ho Chi Minh City. Design/Methodology/Approach: This was a quantitative study in which the authors compile theories, analyze and synthesize scales for research concepts, and propose research models. The online survey collected 532 answer sheets from professors and lecturers from universities in Ho Chi Minh City, of which 525 were valid and included in SmartPLS 3 to evaluate the validity and reliability of the scale and to analyze the relationship among the concepts in the suggested model. Findings: The results show that several factors significantly impact employee satisfaction in the field of education, such as job promotion, leadership or supervision, working environment, income, and the job itself. In addition, both satisfaction and organizational culture impact organizational commitment. The study's findings have implications for educational institutions, lecturers, policymakers, researchers, and funding agencies. They highlight the importance of factors like leadership development and organizational culture in enhancing job satisfaction and commitment among lecturers, offering valuable insights for improving the educational environment in Ho Chi Minh City and beyond. Originality: The results aligned with previous studies presented in the literature section. However, this study revealed some specific characteristics of lecturers in universities in Ho Chi Minh City, Vietnam, where lecturers focused on personal development but were committed to the organization via job satisfaction and culture. Doi: 10.28991/ESJ-2023-SIED2-021 Full Text: PD