基于步进衰减器法的噪声系数分析仪噪声系数校准的一种方法

介绍了噪声系数分析仪对噪声系数这一关键参数校准的改进方法。由于噪声系数的技术指标很高,要求达±0.05 dB,在校准时必须减少端口失配所引入的测量不确定度。在JJF 1460—2014中,通过在步进衰减器两端加隔离器来减少端口失配所引入的不确定度。经过分析,认为在无隔离器的实验室中,通过在步进衰减器两端各增加一个约10 dB的精密固定衰减器,同样可以达到与隔离器相同的校准能力。根据试验数据给出了校准结果的分析以及相应的不确定度评定结果。     

使用噪声系数仪N8975A测量大增益放大器

本文主要研究噪声系数仪N8975A测量放大器增益的基本原理,分析探讨噪声系数仪N8975A测量大增益放大器的3种不同方法,并进行了测试验证,结果表明3种测量方法一致性良好。     

野战型雷达接收机噪声系数测试仪

本文阐述了野战型雷达接收机噪声系数测试仪的设计思想、结构特点、工作原理测试仪的使用方法。重点介绍应用新器件、新技术实现对雷达接收机噪声系数的测试。     

N8975A噪声系数仪校准问题探讨

本文根据N8975A噪声系数仪的技术性能 ,对其校准进行了探讨 ,并介绍了数据处理的方法     

HP8970B噪声系数测量仪的故障分析与检修

HP8970B是一种智能化的高精度噪声系数测量仪，仪器利用它自身所拥有程序对其工作情况进行管理和监控。仪器运行校准程序时，通过相应的功能、参数设定和测试检查仪器是否工作正常，发现故障时输出相关的故障代码，并指出校准失败；它还有若干的特殊功能和指令供维修人员使用，以对某项功能或某一电路进行单独的控制，检查和校准。     

JJF1460-2014《噪声系数分析仪校准规范》解读

<正>噪声参数是微波无线电领域中一个很重要的参数。一般来说,噪声是有害的,它干扰甚至淹没有用的信号,致使通信中断或者根本无法辨识目标信号。为了减小或衡量噪声对无线电通信的影响,以适应通信技术的发展,长期以来,人们对噪声所涉及问题进行了广泛研究,建立了一套衡量系统或器件噪声大小的参数体系。在这些参数中,噪声系数发挥举足轻重的     

关于动态信号分析仪测量SQUID噪声的讨论

做为最灵敏的磁通－电压传感器超导量子干涉器（ＳＱＵＩＤ）通常用于测量微弱信号,因此,噪声水平是其主要特征指标。目前,ＳＱＵＩＤ的噪声功率谱主要是用ＨＰ公司的动态信号分析仪（Ｄｙｎａｍｉｃ Ｓｉｇｎａｌ Ａｎａｌｙｚｅｒ ３５６６５Ａ或３５６７０Ａ）来测量,仪器的设置不同,所得的测试结果差异很大。本文针对ＳＱＵＩＤ噪声的测试问题,根据实际的经验,对动态信号分析仪的设置进行几点讨论。     

测量过程的实现

文章论述了ISO10012测量管理体系中测量过程实现的内容及测量过程控制方法，找出存在于测量和计量确认过程中的质量规律，从而满足所规定的要求。     

噪声测量中频率计权的实现

根据IEC651-1977规定的A、B、C计权特性和数据表,模仿人在不同情况下对声信号的主观感觉,利用网络理论,设计了结构简单的滤波电路,其性能符合一级声级计要求。     

实时频谱分析仪中CCDF测量功能的实现

实时频谱分析仪可以对通信信号进行实时测试,符合现代通信分析仪的发展趋势。CCDF测量是实时频谱分析仪的关键技术之一,对于测量多载波信号非常有用。它普遍应用在2G和3G无线信号测量上。本文介绍了实时频谱分析仪的总体框架,重点阐述了CCDF测量功能的原理和处理流程。并以OFDM系统(正交频分复用)为应用背景验证了这种算法的有效性。     

Non-destructive Case Depth Determination by Means of Low-Frequency Barkhausen Noise Measurements

The availability of a fast and reliable method for non-destructive case depth determination which can be used to directly monitor the quality of various heat treatment processes is of great interest. Conventionally hardened steel components are analyzed by means of depth-resolved microhardness measurements providing the case hardening depth (CHD) of the material. However, as a consequence of mechanical destruction, the investigated part cannot be used in its original state anymore and needs to be replaced by a twin part whose properties might be different. In this work, a new approach of non-destructive CHD determination based on Barkhausen noise analysis with an excitation frequency of 0.5 Hz is described. The use of a low frequency allows to enhance the penetration depth of the external magnetic field and to reduce the eddy current damping of the filtered Barkhausen (BN) signal at the same time. In this way, simultaneous information about the hard case and the soft base material core is experimentally accessible. Various measurands derived from the detected BN signals are sensitive to the different magnetic properties of the case and the core. The so-obtained correlations with the measured CHD can be used for non-destructive CHD determination by means of appropriate calibration data. The investigated sample set consists of cylindrical parts of 18CrNiMo7-6 which were case-hardened and ground in order to provide graded CHD values up to 3.6 mm. The sensitivity of the tested low-frequency method will be quantitatively demonstrated over the complete range of interest and its potential for industrial applications will be discussed.     

Simultaneous Determination of Transistor Noise, Gain, and Scattering Parameters for Amplifier Design through Noise Figure Measurements Only

A method for the simultaneous determination of transistor noise and gain parameters through noise figure measurements has been presented recently. An improved version of the method is presented here which can also yield all the scattering parameters needed for designing amplifiers. By means of a proper (computer-aided) data-processing technique, s11, s22, |s12| , |S21|, and s12s21 are determined. As experimental verifications, the characterization of a GaAs MESFET versus frequency (4-8 GHz) is reported.     

Automating FM Noise Measurements

With the proliferation of spectrally pure RF sources the developers of RF test systems have been faced with the problem of verifying this spectral purity, particularly the FM-noise sideband power levels associated with these sources. The PLL discriminator is one possible solution; however, its major drawback is that is requires a frequency source with spectral purity characteristics which are better than the source to be measured. The delay-line discriminator technique is an alternate solution to the problem. The latter technique has been successfully implemented and integrated into an automatic test system; its success is measured not only by its demonstrated performance characteristics but also by its simplicity which ensures its reliability and ease of maintenance.     

Determination of the Superconducting Penetration Depth From Coplanar-Waveguide Measurements

We introduce a novel transmission-line method for determining the penetration depth in thin high-temperature superconducting (HTS) films. The method is based on the accurate measurement of the inductance per unit length of a superconducting coplanar-waveguide (CPW) transmission line fabricated on the HTS sample. Using the experimentally obtained inductance per unit length, we interpolate the penetration depth from a table of numerically determined values of inductance (per unit length) as a function of penetration depth, calculated from a coupled transmission-line model. A novelty of our procedure is the utilization of the multiline thru-reflect-line (TRL) method and the calibration-comparison method to accurately determine the inductance per unit length of the superconducting transmission line. By measuring different CPW geometries patterned onto the same thin-film sample, we can verify our penetration depth values. We demonstrate this technique by extracting the penetration depth for several different HTS films at 76 K. Estimated uncertainties in the extracted penetration depth are also provided. Contribution of an agency of the US government not subject to copyright.     

The Principles of Depth Analysis of Surface Hardened Layers by the Magnetic Noise Method

Abstract

Theoretical and experimental results useful for layer-by-layer depth analysis of the properties of surface-hardened layers in steels are presented. The design of an apparatus for this purpose is discussed.     

Novel Noise Parameter Determination for On-Wafer Microwave Noise Measurements

A novel method to determine the noise parameters of receivers or devices under test (DUTs) for on-wafer microwave noise measurements is presented. An iterative technique is utilized, and fast convergence is achieved by the proposed impedance selection principle. This proposed method reduces the parameter variations in the conventional methods. The impact of the impedance difference on noise parameter determination is experimentally evaluated using a DUT fabricated in a standard 90-nm CMOS technology.     

Process Capability Analysis for NonLinear Profiles Using Depth Functions

There are practical situations in which the quality of a process or product can be better characterized by a functional relationship between a response variable and one or more explanatory variables, which is called profile. Such profiles frequently can be represented adequately using linear or nonlinear models. While there are several studies in monitoring profiles, there are few studies to evaluate the capability of a process with profile quality characteristic; specifically, there is no method in the literature to analyze process capability characterized by nonlinear profiles. In this paper, we propose two methods to measure the capability of these processes, based on the concept of functional depth. These methods do not have distributional assumptions and extend to functional data the Process Capability Indexes proposed by Clements 1 to measure the capability of a process characterized by a random variable. Performance of the proposed methods is evaluated through simulation studies. An example illustrates the applicability of these methods. Copyright © 2013 John Wiley & Sons, Ltd.     

A New Method to Extract Noise Parameters Based on a Frequency- and Time-Domain Analysis of Noise Power Measurements

A new on-wafer noise parameter measurement method at a 2.8-18-GHz frequency band is presented. This measurement method is based on both temporal and spectral analysis of noise power measurements. We present the method and the experimental results on an active two-port. It requires less equipment than the classic noise parameter measurement method. It gives direct results for 801 points in the 2.8-18-GHz frequency band.     

A Technique for Differential Noise Figure Measurement of Differential LNAs

This paper presents an approach to measure the noise figure of a differential low-noise amplifier (LNA) based on familiar ldquocold-hotrdquo single-ended noise figure measurements. To demonstrate the usefulness of this approach, measurement results are presented for a wideband differential LNA designed to be used as the first stage of the receiver in the Square Kilometre Array radio telescope. The presented LNA achieves less than 0.41 dB of differential noise figure in the 700 MHz to 1.4 GHz band, differential S₁₁ <-13 dB, differential S₂₁ between 18 and 14 dB, single-ended output P1 dB of -8.2 dBm, and output IP3 of -1 dBm while consuming 81 mA from a 1.3-V supply. The approach of measuring the differential noise figure may be automated with one switch at the output of a standard noise source and one switch at the input to a standard noise figure analyzer or a noise figure meter, allowing for automated noise figure measurements of differential LNAs based on the differential pair topology.