| Noise figure is one of key parameters of judging RF devices’ capability of processing small-signals.Therefore,the performance of NFA(noise figure analyzer),being the core instrument,directly determines the accuracy of the measured noise figure.As a result,the validity of measurement results depends notably on strict calibration of important indicators of NFA.Manual calibration according to "JJF1460-2014 Noise figure analyzer calibration specification" can be a tough work,because it is complicated and inefficient.It is necessary to design an automated calibration system improving the speed of measuring and the accuracy to satisfy the need of practical work.Along with the development and the popularization of virtual instrument technology,it is now possible to design an automated system as a replacement.LabVIEW as a typical graphical programming language outmatches most of traditional programming languages in the field of automated testing and calibration,because it is flexible,intuitive,easy to understand and debug.Firstly,this essay introduces the concept of noise coefficient,related knowledge,the principle and common methods of measuring noise figure.Afterwards,the items and requirements of this calibration system are analyzed.Appropriate devices used in the calibration are selected according to the measurement range and precision.The application of virtual instrument technology and LabVIEW in the automated calibration of NFA is discussed.And a set of automated calibration based on LabVIEW is done.At last,the uncertainty of measurement of several items is evaluated and several methods are used to validate the validity and reliability of the system. |
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