共查询到20条相似文献,搜索用时 46 毫秒
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《Industrial Electronics, IEEE Transactions on》2008,55(11):3855-3864
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A nonlinear mathematical model of phase-locked loops with limiter phase detectors in the presence of noise is presented. The model, which is an extension of the well-known baseband model of loops with sinusoidal phase detectors without limiters, incorporates a modified nonlinear phase detector characteristic, the form of which is changed if the input carrier-to-noise ratio alters, as well as a modified phase noise as an input to the model. Both the modified phase detector characteristic and the spectral density of the modified noise term are calculated specifically for sinusoidal, triangular, and sawtooth types of limiter phase detectors, allowing the application of various methods to determine the loop noise performance. As an example, the phase error variance of a first-order phase-locked loop is calculated, thereby showing a strong dependence on the specific phase detector realization. 相似文献
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Based on the Fokker-Planck techniques, the time-dependent mean and variance of phase error of the first-order phase-locked loop in the presence of white Gaussian noise have been obtained via stochastic differential equations. The steady-state variance reduced from the transient case is simple in its form and agrees closely with the previous results obtained by different approaches. 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》1980,26(4):482-486
The time-dependent probability-density function (pdf) of the state vector for the second-order phase-locked loop (PLL) is shown to be determined by an orthogonal function expansion. The expansion coefficients are the solutions to infinite dimensional ordinary differential equations, which are derived by Ito's stochastic calculus. Numerical solutions can be obtained by truncating them. It is also shown that certain parameters which characterize the distribution of a random variable on a circle, such as phase error, can be expressed by only one coefficient of the Fourier series of its pdf. 相似文献
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A study of a controlled cryosurgical process is presented. This study is based on the energy equations describing the probe response and the phase change occurring in the medium. First-order nonlinear differential equations (state equations) are obtained by applying the integral-solution method. In order to obtain maximal cell destruction, it is desired to control a specific cooling rate at the solid-liquid interface. This cooling rate defines the desired trajectories of the state variables through the state equations. In order to satisfy the cooling rate condition on the freezing front, a closed-loop is designed to control the probe temperature program. A simple analysis of the system stability employed linearization at several points along the desired trajectories. Ranges of stability were obtained for a system containing a proportional-integral controller. It was demonstrated that these stability ranges depend mainly on the selected sampling time of the discrete control loop and that the phase-change process does not significantly affect the stability results. A complete study of the nonlinear equations was performed by a computer simulation program which enables the selection of the final values of the controller parameters, in order to minimize the error and to ensure stability. In addition, the simulation program gives information about the effects of the A/D and D/A converters accuracy on the performance of the control loop. An A/D converter accuracy of 12 bits was found necessary in order to reduce the oscillations in probe temperature to acceptable values. The simulation also yields a complete calculated temperature field in the tissue during the controlled process. From these simulated results it can be seen that oscillations of +/- 0.5 degrees C in the desired probe temperature do not significantly affect the desired cooling rate at the freezing front. An initial overshoot of 1.5 degrees C in the desired probe temperature was obtained both experimentally and theoretically from the simulation. When this initial overshoot occurs at the beginning of the freezing process, it causes an error in freezing front velocity and consequently in ice-front position. From the numerical simulation, it can be deduced that the cooling rate obtained at the front deviates from the desired value by approximately 1%. The probe-temperature error increases at two instants: a) during the super-cooling effect and the subsequent sudden crystallization, and b) when the probe temperature is below -80 degrees C and unstable boiling of the cooling medium causes oscillations. 相似文献
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Yu. A. Sidorkina V. V. Sizykh B. I. Shakhtarin V. A. Shevtsev 《Journal of Communications Technology and Electronics》2016,61(7):807-816
The Markovian mathematical model of the Kostas phase-locked loop subjected to the simultaneous actions of additive harmonic interferences and a white Gaussian noise, which are described by stochastic differential equations involving the influence of the low-pass filters of the control loop on the useful pulsed signal shape, is discussed. The statistical characteristics of the error signal are analyzed in the linear approximation. 相似文献
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To obtain the steady-state probability distribution of the phase error for a phase-lock loop driven by the sum of modulated carrier and narrowband stationary noise, a familiarity with Fokker-Planck techniques is usually a prerequisite to formulate a differential equation that has the required distribution as its solution. Here a simpler treatment is offered, which uses the more standard tools of probability theory. The distribution of the frequency error is also considered. 相似文献
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Saffrine Kingsly Sangeetha Velan Malathi Kanagasabai Sangeetha Subbaraj Yogeshwari Panneer Selvam Bhuvaneswari Balasubramaniyan 《International Journal of Electronics》2019,106(4):620-633
In this paper, a compact, single-section, Ultra-wideband (UWB) coupled-line coupler designed using concentric loop in the signal plane and defect in the ground plane is presented. Bandwidth enhancement is achieved with low coupling at the X-band satellite downlink range to improve the signal strength for defence applications. Return loss greater than 15 dB and isolation greater than 20 dB is achieved over the entire UWB band. The prototype is fabricated and tested to validate the simulation results. Further to detect the quality of the output signal, signal integrity analysis is performed and metrics such as error vector magnitude (EVM), magnitude and phase error, eye pattern, constellation plots and signal to noise ratio are presented for the proposed UWB coupled-line coupler. 相似文献
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Keang-Po Ho 《Photonics Technology Letters, IEEE》2003,15(9):1216-1218
When nonlinear phase noise is compensated by the received intensity, simple formulas are derived for the error probability of differential phase-shift keying signals. Simulation is conducted to verify the error probability. The tolerance of nonlinear phase noise is doubled by the compensator, allowing doubling of the transmission distance if nonlinear phase noise is the dominant impairment. 相似文献
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Keang-Po Ho 《Photonics Technology Letters, IEEE》2003,15(9):1213-1215
The error probability is calculated for phase-modulated systems with nonlinear phase noise. Using the assumption that the phase of amplifier noise and nonlinear phase noise are independent of each other, the error probability and penalty are calculated for both phase-shift keying (PSK) and differential phase-shift keying (DPSK) systems. The mean nonlinear phase shift must be less than about 1.00 and 0.63 rad for a penalty less than 1 dB for PSK and DPSK systems, respectively. 相似文献
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Tanmoy Banerjee Biswajit Karmakar Bishnu Charan Sarkar 《AEUE-International Journal of Electronics and Communications》2012,66(7):593-597
The present letter reports a simple chaotic electronic oscillator. A single amplifier biquad (SAB) based active high-Q Band Pass Filter (BPF) is converted into a chaotic oscillator by introducing a single passive nonlinear element in the form of a general purpose pn junction diode, and a storage element in the form of an inductor. The chaotic circuit is mathematically modeled, which is a set of four coupled first-order autonomous nonlinear differential equations. The behavior of the proposed circuit is investigated through numerical simulations and electronic hardware experiments. It is found that the circuit shows complex behaviors, like, bifurcations and chaos, for a certain range of circuit parameters. The chaotic behavior of the circuit is ensured qualitatively by bifurcation diagram, phase plane plot and experimentally obtained power spectrum, and quantitatively by Lyapunov exponents and Kaplan–York dimensions. 相似文献
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A. M. Kurbatov R. A. Kurbatov 《Journal of Communications Technology and Electronics》2013,58(8):840-846
The error of the fiber-optic gyroscope (FOG) rotation rate measurement is considered. This error is induced by FOG vibrations (for open- and closed-loop FOGs). For a closed-loop FOG, a differential equation describing the loop dynamics is derived. The coefficients of this equation contain terms varying in time with the vibration frequency. For the first time, it is shown that, in addition to the traditional rotation rate measurement error due to the superimposition of vibration-induced optical power oscillations and the phase difference in the FOG coil, there is one more error, which is due to vibration modulation of the loop bandwidth. Alternative methods of information processing are investigated, and, on the basis of them, a new circuit is proposed for the suppression of vibration errors. 相似文献
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针对鉴频鉴相器(PFD)的盲区现象对锁相环路的锁定速度的影响,设计了一种PFD结构,可以实现锁相环路的快速锁定。该结构在传统PFD的基础上,利用内部信号的逻辑关系进行逻辑控制,其输出特性呈现非线性;在输入相位差大于π时,抑制了复位脉冲的产生,避免了输入时钟边沿的丢失,有效消除了盲区,加快了锁相环的锁定速度。设计采用SMIC 0.18μm标准CMOS工艺,采用全定制设计方法对该PFD结构进行了设计、仿真分析和验证。结果表明,采用该PFD结构的锁相环,在400 MHz工作频率下锁定时间为2.95μs,锁定速度提高了34.27%。 相似文献
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K. Cvecek G. Onishchukov K. Sponsel A.G. Striegler B. Schmauss G. Leuchs 《Photonics Technology Letters, IEEE》2006,18(17):1801-1803
We experimentally investigate the amplitude and phase transfer characteristics of a modified nonlinear optical loop mirror (NOLM) with a directional attenuator (DA-NOLM) optimized for differential phase-shift keying signal regeneration. The results show that the phase relation is preserved in the setup and thus the DA-NOLM is suitable for amplitude regeneration of phase-shift-keyed signals. 相似文献
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二阶锁相环非线性捕获和非线性跟踪性能研究 总被引:3,自引:0,他引:3
采用MATLAB软件,编制了求解描述二阶PLL非线性捕获的二阶非线性微分方程的程序,计算机自动绘制了相轨迹和时间响应图;求出了二阶PLL的捕获带随初始相差的变化关系曲线. 相似文献