An investigation of noise factor effects in parameter design

Parameter design aims to determine nominal values of a set of design parameters so as to minimize variability in one or more key performance measures, in the presence of uncertainties in the design parameters, whilst maintaining the required nominal (design point) performance and the overall design concept. A theoretical analysis of some aspects of parameter design and of some related approximate methods is carried out and the results studied with the aim of determining the effect of changes in the magnitudes of the uncertainties in the design parameters on the resulting values of nominal parameter values in the optimum design. It is shown that there is reason to expect that, allowing for the effects of constraints, a given parameter design would be robust against overall changes, by a constant factor, in the parameter uncertainties but not in the presence of changes in individual parameter uncertainties, or by numerous such changes when the change factor varies between individual parameters. Some numerical results are obtained for problems in beam design and are shown to support the above assertions. The results imply that nominal values in a previously determined robust design may continue to be valid when parameter tolerances change, provided such changes are by the same factor for all free design parameters, i.e. those not fixed on a constraint boundary. Copyright © 2002 John Wiley & Sons, Ltd.     

A high-quality 120 GHz millimeter-wave generation without laser phase noise

A 120-GHz millimeter-wave system using two lasers and two Mach–Zehnder modulation (MZM) with frequency 8-tupling of the radio frequency local oscillator’s signal frequency is proposed and demonstrated. The first MZM is the even-order harmonic modulations output and then optical filter filters the 0-order wave. The second MZM is the single sideband suppression output. In the system, two light components with the same phase noise are generated. The millimeter wave can avoid the laser phase noise. It has simplified the system, so the fibre dispersion is reduced.     

Wideband on-wafer noise measurement setup for noisecharacterization of active devices in the low VHF band

This paper addresses a new wideband on-wafer measurement test set designed for noise characterization of microwave active devices over the frequency range of 300 kHz to 150 MHz. Noise parameters obtained from the multiple impedance technique on a GaAlAs/GaAs heterojunction bipolar transistor (HBT) from 300 kHz to 70 MHz are reported and compared with low-frequency noise data. Investigation of the excess noise sources of III-V HBT's is performed well above the 100 kHz frequency limit of standard dynamic signal analyzers and noise modeling of these devices is reported     

Design parameter selection in the presence of noise

Themethod of imprecision is a design method whereby a multi-objective design problem is resolved by maximizing the overall degree ofdesigner preference: values are iteratively selected based on combining the degree of preference placed on them. Consider, however, design problems that exhibit multiple uncertainty forms (noise). In addition to degrees of preference(imprecision) there areprobabilistic uncertainties caused by, for example, measuring and fabrication limitations. There are also parameters that can take on any valuepossible within a specified range, such as a manufacturing or tuning adjustment. Finally, there may be parameters which mustnecessarily satisfly all values within the range over which they vary, such as a horsepower requirement over a motor's different speeds. This paper defines a best set of design parameters for design problems with such multiple uncertainty forms and requirements.     

基于舰船噪声的海底单参数反演

利用舰船噪声进行地声参数反演是近年来的热门研究课题之一。目前大多数利用舰船噪声的反演方法依赖于多参数海底模型,而多维参数的求解加大了反演的复杂度,因此,基于海底单参数模型,提出一种使用舰船噪声作为声源的海底单参数反演方法。基于实验数据进行海底单参数反演,并用反演得到的结果,对实验海域的传播损失进行预报。最后,对海底单参数与频率的关系进行了拟合和研究,验证了反演方法的有效性。     

基于环境噪声的浅海海底单参数反演

利用环境噪声反演浅海海底声学特性一直是学者们研究的热门课题之一,目前绝大多数的噪声场建模方法依赖于多维海底模型,而多维参数的求解过程加大了反演的复杂度。减少反演参数个数可以有效降低反演的复杂性,提高反演的速度,以此为目的开展了基于单个参数海底模型的噪声场建模研究,并计算得到了基于海底单参数的噪声场空间相干系数表达式。通过与传统模型的对比,验证了该计算模型的有效性。结合实验数据,利用该模型对实验海域进行了海底单参数反演,并结合海底反射临界角确定了实验海域的沉积物类型为粉砂质砂,该结论与文献记载相吻合。     

Optical noise induced by Gaussian sources in stokes parameter measurements

A novel formalism for determining the source-induced noise in Stokes parameter measurements is derived for sources with Gaussian statistics. The formalism is based on a concise expression for the autocovariance functions of the Stokes parameters in terms of the second-order correlation properties of the optical field. At the output of an optical system, source-induced noise can result not only from the intensity fluctuations of the source but also from phase or polarization fluctuations. To describe the effect of the system, another formalism for the propagation of the second-order correlation properties of the optical field is derived. We apply the formalisms to analyze source-induced noise at the output of a birefringent medium, and in coherence-multiplexing networks.     

基于改进确定-随机子空间算法的桥梁结构模态参数识别

模态识别精度评价贯穿模态识别研究的全过程,但基于单一或少数算例的模态识别精度评价方法存在偶然性,因此提出一种基于结构响应数据库评价模态识别精度的方法。数据库的关键数据是结构的模态参数理论值和结构响应;对于集中质量模型,提出一种基于模态参数构建结构物理模型(质量、刚度和阻尼矩阵),进而计算结构响应的数据库构建方法,并用算例验证了可行性。针对随机子空间法定阶难、虚假模态剔除难的问题,提出一种基于奇异熵增量定阶和稳态图两阶段虚假模态剔除的优化随机子空间法,并利用数据库方法对优化的随机子空间法进行了识别精度评价,结果表明：基于数据库的模态识别精度评价方法可行;优化的随机子空间法频率和振型的识别精度高、阻尼比的识别精度较低。     

An enhanced current-mode instrumentation amplifier

An enhanced current-mode instrumentation amplifier is presented. The circuit is based on a current conveyor-operational amplifier combined configuration that offers significant improvement in accuracy as compared with the basic current-mode instrumentation amplifier based on current conveyors only     

An important parameter in high-temperature superconductivity

It is widely held that the single most important parameter describing the strength of the electron-phonon interaction in superconductivity is the mass enhancement factor λ, and that the maximum possible transition temperature for a given class of materials (e.g., the polyvalent metals) is attained for a very large value, λ≈3, of the parameter. We show that it is not likely that the highest attainable values ofT _c will reflect such large values of λ. Instead, we expect that they will be associated with values of λ that do not differ greatly from a value of about 1.5, and with very large values of the parameterA, whereA is the area under the electron-phonon interaction spectrum α² F(v). This is certainly the case forNb ₃ Sn, which has aT _c of 18 K.     

An apparatus for measuring infra-low-frequency noise

Conclusion Using the apparatus developed by the authors, a series of measurements was carried out of the noise factor of prototypes of MOS transistors with an induced p-channel which were fabricated in the technological laboratory of the microelectronics chair of the Moscow Engineering Physics Institute.The apparatus described allows measurement of the spectral density of the noise (or the noise factor) by the comparison method in the frequency range from 0.1 to 100 Hz. The effective filter passband varies in the range from 10 to 100% of the resonant frequency. The sensitivity of the apparatus was determined by the sensitivity of the broadband amplifier used, and in our experiments it was 0.1V²/Hz.The measurement error, which is determined by the error of each of the blocks of the apparatus, does not exceed 15%.Translated from Izmeritel'naya Tekhnika, No. 8, pp. 74–76, August, 1970.     

Phase noise performance of microwave analog frequency dividers: application to the characterization of oscillators up to the millimeter-wave range

The phase noise performance of two different microwave analog frequency dividers is characterized and compared with the values obtained using simple theories of noise in injection-locked systems. The direct measurement of the divider noise with a low phase noise synthesizer is not accurate enough, and the residual noise technique is used. The noise levels observed using this technique, between -120 and -155 dBc/Hz at a 10 kHz offset frequency, demonstrate that this divider noise is much lower than the phase noise of most microwave free running oscillators, even if this noise is still high with respect to the residual noise of amplifiers realized with the same active devices. The down conversion of microwave sources up to 40 GHz, is proposed as an application example.     

An experimental investigation of YBa2Cu3O7 films at millimeter-wave frequencies

Journal of Superconductivity and Novel Magnetism - We have measured the millimeter-wave (100 GHz) surface resistance of high-quality laserdeposited YBa2Cu3O7 films on SrTiO3 and LaA103 substrates....     

激光陀螺随机噪声参数估计和滤波方法研究

激光陀螺(RLG)中随机噪声是影响其精度的一个重要因素,针对其噪声的特殊性质,采用小波方法去除随机噪声,提高激光陀螺的精度。通过小波分析的参数估计方法获得噪声参数,并用小波阈值滤波方法去除噪声,对某型号的RLG的滤波结果表明了该方法的有效性。     

A cost-effective technique for extending the low-frequency range ofa microwave noise parameter test set

The operating frequency range of an on-wafer noise parameter test set based on the multiple-impedance technique has been extended in the low-microwave frequency range (down to the L-band). A simple technique, using a phase shifter cascaded with the microwave tuner, allows different reflection coefficients of the load impedance to be obtained at the device input. These coefficients are well distributed over the Smith chart in the entire frequency range. As an example, noise parameters of a passive device have been measured between 1 and 8 GHz, and a good agreement between measured and calculated values is observed. This technique has also been used to measure the noise parameters of different heterojunction bipolar transistors. A minimum noise figure of 1 dB was obtained at 1 GHz on a GaAlAs/GaAs HBT which is in agreement with expected results     

一种计算航船对近海海洋环境噪声贡献的算法

为了研究浅海中低频段的海洋环境噪声,文章构建了一种计算航船对近海海洋环境噪声贡献的算法,利用某海域航船信息,结合实际水文参数,对该海域的航运噪声进行了仿真计算。航船信息通过访问船舶自动识别系统数据库获取。主要关注50~400 Hz的中低频段,将仿真计算结果和实验数据进行对比,验证了算法的可靠性,并进行了误差分析。利用该算法可获取接收点处航船噪声的水平方向分布特点,并可初步定量分析航船噪声对海洋环境噪声的贡献。     

An investigation of high-frequency bias-induced tape noise

Bias-induced tape noise remains a major limitation of the SNR in audio magnetic tape recording systems. Defined as the increment in system noise incurred when the bias oscillator is turned on, the noise can originate from a number of different causes; namely, bias oscillator harmonic distortion, magnetized heads, the earth's magnetic field, and an intrinsic noise source. The latter noise source is our primary concern here. Such record system parameters as head-to-tape spacing, gap length, bias current, and bias frequency were investigated with regard to their influence on this intrinsic bias noise source. Two models of the mechanism of intrinsic bias noise are examined. The first, the "amplitude modulation model." proposes that bias noise is generated by amplitude modulation of the recorded bias signal by the physical and magnetic variations of the head-tape system. In this model, bias noise is merely the lower AM sidebands of the recorded bias signal. The second model relates bias noise to the interaction fields in erased tape. This model proposes that these fields behave similarly to normal recording fields and can be "re-recorded" on the tape at an enhanced level. The two proposed mechanisms are examined in the light of the experimental data. The amplitude modulation model is shown to agree with all the observed data with the exception of the existence of bias noise at bias wavelengths smaller than the particle size. The second model, which does not incorporate a wavelength dependency of bias noise, is in qualitative agreement with the observed data. Methods are discussed for reducing the bias noise without materially affecting the system performance.     

An enhanced method for characterizing successive approximationconverters

A strategy for characterizing successive approximation, analog-to-digital converters with quad current switch architectures is described. It permits detailed parameter specification (accuracy and linearity) without recourse to testing every transition voltage. The results show an encouraging reduction in the residual error from 0.144 step (from a currently used test) to 0.048 step with the proposed test for the specific case of 12-b converters. To achieve this result, only 2.6% of the transition voltages require measurement. The percentage of codes to be tested reduces dramatically as the number of bits of the converter increases. The evolution of the proposed test is investigated by examining the cause and effect of superposition errors