• Title, Summary, Keyword: property of quadrature

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A study on the biorthogonally coded Q$^{2}$AM with constant envelope property (정진폭특성을 갖는 Birothogonal 부호로 부호화된 Q$^{2}$AM(Quadrature Quadrature Amplitude Modulation)에 관한 연구)

  • 박인재;심수보
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.21 no.9
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    • pp.2470-2480
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    • 1996
  • The energy efficiency and bandwidth efficiency are two important criterion in designing a modulation scheme Especially the constant envelope property must be considered as in the non-linear channel tht exit, for example in the nonlinear amplifiers for satellite repeater. The Q$^{2}$AM(Quadrature Quadrature Amplitude Modulation) is a new modulation scheme which combines the Q$^{2}$PSK(Quadrature Quadrature Phase Shift Keying) scheme which increases the signal space dimension and the QAM scheme which increases the bandwidth efficiency using the multi-level signal. The Q$^{2}$AM scheme has by far superior spectrum efficiency compared with the existing modulation schemes. Applying this scheme in the non-linear communication system increses the bandwidth efficiency but cannot envelop property. In this paper, a new system architecture is suggested which satisfies the large spectrum efficiency and constant envelope property by implementing the linear block coding prior to the Q$^{2}$AM modulation. the system has improved in performance by gaining the constant envelope and the additional coding gain. We able to observe the performance improvement of the suggested system(at BER=10$^{-5}$ ) of 4.4 dB for the 16-QAM and 0.7 dB for the Q$^{2}$PSK under the exact spectrum efficiency.

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ON SOME SOLUTIONS OF A FUNCTIONAL EQUATION RELATED TO THE PARTIAL SUMS OF THE RIEMANN ZETA FUNCTION

  • Martinez, Juan Matias Sepulcre
    • Bulletin of the Korean Mathematical Society
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    • v.51 no.1
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    • pp.29-41
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    • 2014
  • In this paper, we prove that infinite-dimensional vector spaces of -dense curves are generated by means of the functional equations f(x)+f(2x)+${\cdots}$+f(nx) = 0, with $n{\geq}2$, which are related to the partial sums of the Riemann zeta function. These curves ${\alpha}$-densify a large class of compact sets of the plane for arbitrary small ${\alpha}$, extending the known result that this holds for the cases n = 2, 3. Finally, we prove the existence of a family of solutions of such functional equation which has the property of quadrature in the compact that densifies, that is, the product of the length of the curve by the $n^{th}$ power of the density approaches the Jordan content of the compact set which the curve densifies.

Experimental Considration of Multi-order Sampling for Digital Beamforming (디지털 빔포밍을 위한 다차 샘플링 방법의 실험적 고찰)

  • 나병윤;정목근
    • Journal of Biomedical Engineering Research
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    • v.19 no.2
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    • pp.105-112
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    • 1998
  • In this paper, several bandwidth sampling methods were compared using experimental result in which contains "multi-order sampling", which was proposed for envelope detections in RF ultrasonic signals. A "Quadrature sampling method" and "Second-order sampling method" were compared with it. The resultant image of second-order sampling method introduces too much error as compared with the result of quadrature sampling. But Multi-order sampling method, specialy 5-th sampling method showed quite good envelope detection property. This means that more economical and quite good performance digital beamforming system can be built by adopting this multi-order sampling method.s multi-order sampling method.

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CACB-Q2AM Modulation for High Bandwidth Efficiency and Constant Amplitude Signal Transmission (높은 대역폭 효율과 정진폭 신호 전송을 위한 CACB-Q2AM 변조)

  • Hong, Dae-Ki;Kang, Sung-Jin
    • Journal of Internet Computing and Services
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    • v.9 no.1
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    • pp.21-32
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    • 2008
  • In this paper, we propose new modulation schemes using the conventional CACB (Constant Amplitude Coded Multicode Biorthogonal) modulation with constant amplitude property. Also the proposed modulation schemes supports high transmission data rate by increasing the spectral efficiency, In order to obtain the high spectral efficiency, the $Q^2$AM (Quadrature-Quadrature Amplitude Modulation) and CA-$Q^2$AM (Constant Amplitude-$Q^2$AM) are used. We explain the simplest combining modulation scheme of CACB and $Q^2$AM (i.e., CACB-$Q^2$AM). However, this modulation scheme cannot support the constant amplitude property. Hence the first CACB-CA-$Q^2$AM (or CACB-CA-$Q^2$AM I) modulation scheme is proposed for the constant amplitude property. In the modulation scheme, the redundant constant amplitude encoding (spectral efficiency decrease) is required. Therefore, the second CACB-CA-$Q^2$AM (or CACB-CA-$Q^2$AM II) modulation scheme is proposed retaining the constant amplitude and the spectral efficiency. Computer simulations show that the proposed CACB-CA-$Q^2$AM II is the efficient modulation scheme.

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Design of a 960MHz CMOS PLL Frequency Synthesizer with Quadrature LC VCO (960MHz Quadrature LC VCO를 이용한 CMOS PLL 주파수 합성기 설계)

  • Kim, Shin-Woong;Kim, Young-Sik
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.46 no.7
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    • pp.61-67
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    • 2009
  • This paper reports an Integer-N phase locked loop (PLL) frequency synthesizer which was implemented in a 250nm standard digital CMOS process for a UHF RFID wireless communication system. The main blocks of PLL have been designed including voltage controlled oscillator, phase frequency detector, and charge pump. The LC VCO has been used for a better noise property and low-power design. The source and drain juntions of PMOS transistors are used as the varactor diodes. The ADF4111 of Analog Device has been used for the external pre-scaler and N-divider to divide VCO frequency and a third order RC filter is designed for the loop filter. The measured results show that the RF output power is -13dBm with 50$\Omega$ load, the phase noise is -91.33dBc/Hz at 100KHz offset frequency, and the maximum lock-in time is less than 600us from 930MHz to 970MHz.

CACB-Q2PSK Modulation for Efficient Bandwidth Utilization and Constant Amplitude Signal Transmission (효율적인 대역폭 이용과 정진폭 신호 전송을 위한 CACB-Q2PSK 변조)

  • Hong, Dae-Ki
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.9 no.1
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    • pp.93-99
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    • 2008
  • In this paper, we propose new modulation schemes using the conventional CACB modulation with constant amplitude property. Also the proposed modulation schemes supports high transmission data rate by increasing the spectral efficiency. In order to obtain the high spectral efficiency, the $Q^2$PSK and CA-$Q^2$PSK are used. We explain the simplest combining modulation scheme of CACB and $Q^2$PSK (i.e., CACB-$Q^2$PSK). However, this modulation scheme cannot support the constant amplitude property. Hence the first CACB-CA-$Q^2$PSK (or CACB-CA-$Q^2$PSK I) modulation scheme is proposed for the constant amplitude property. In the modulation scheme, the redundant constant amplitude encoding (spectral efficiency decrease) is required. Therefore, the second CACB-CA-$Q^2$PSK (or CACB-CA-$Q^2$PSK II) modulation scheme is proposed retaining the constant amplitude and the spectral efficiency. Computer simulations show that the proposed CACB-CA-$Q^2$PSK II is the efficient modulation scheme.

A Comparative Study of Transcription Techniques for Nonlinear Optimal Control Problems Using a Pseudo-Spectral Method

  • Kim, Chang-Joo;Sung, Sangkyung
    • International Journal of Aeronautical and Space Sciences
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    • v.16 no.2
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    • pp.264-277
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    • 2015
  • This article investigates various transcription techniques for the Legendre pseudospectral (PS) method to compare the pros and cons of each approach. Eight combinations from four different types of collocation points and two discretization methods for dynamic constraints, which differentiate Legendre PS transcription techniques, are implemented to solve a carefully selected test set of nonlinear optimal control problems (NOCPs). The convergence property and prediction accuracy are compared to provide a useful guideline for selecting the best combination. The tested NOCPs consist of the minimum time, minimum energy, and problems with state and control constraints. Therefore, the results drawn from this comparative study apply to the solution of similar types of NOCPs and can mitigate much debate about the best combinations. Additionally, important findings from this study can be used to improve the numerical efficiency of the Legendre PS methods. Three PS applications to the aerospace engineering problems are demonstrated to prove this point.

A review of effects of partial dynamic loading on dynamic response of nonlocal functionally graded material beams

  • Ahmed, Ridha A.;Fenjan, Raad M.;Hamad, Luay Badr;Faleh, Nadhim M.
    • Advances in materials Research
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    • v.9 no.1
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    • pp.33-48
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    • 2020
  • With the use of differential quadrature method (DQM), forced vibrations and resonance frequency analysis of functionally graded (FG) nano-size beams rested on elastic substrate have been studied utilizing a shear deformation refined beam theory which contains shear deformations influence needless of any correction coefficient. The nano-size beam is exposed to uniformly-type dynamical loads having partial length. The two parameters elastic substrate is consist of linear springs as well as shear coefficient. Gradation of each material property for nano-size beam has been defined in the context of Mori-Tanaka scheme. Governing equations for embedded refined FG nano-size beams exposed to dynamical load have been achieved by utilizing Eringen's nonlocal differential law and Hamilton's rule. Derived equations have solved via DQM based on simply supported-simply supported edge condition. It will be shown that forced vibrations properties and resonance frequency of embedded FG nano-size beam are prominently affected by material gradation, nonlocal field, substrate coefficients and load factors.

An Analysis of Electromagnetic Wave Scattering for the Elliptic-Multi Layer Dielectric Cylinders (다층타원 유전체주의 전자파 산란 해석)

  • 박동희;김정기
    • The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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    • v.2 no.3
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    • pp.26-31
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    • 1991
  • The scattering property of TMz illuminated a elliptic dielectric cylinders with arbitrary cross section are analyzed by the boundary element techniques. The boundary element equations are for- mulated via Maxwell's equations, weighted residual of Green's theorem, and the boundary conditions. The unknown surface fields on the boundaries are then calculated by the boundary element integral equations. Once the surface fields are found, the scattered fields in far-zone and scattering widths (SW) are readily determined. To show the validity and usefulness of this formulation, computations are compared with those obtained using analytical method and one layer circular cylinder. As exten- sion to arbitrary cross-sectioned cylinders, plane wave scattering from a elliptic dielectric cylinders are numerically analyzed. A general computer program has been developed using the quadratic ele- ments(Higher order borndary elements) and the Gaussian quadrature.

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