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Time Measurement
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
Many applications require multiple clocks to be synchronized or set to the same time. Using the time interval measurement methods described in Section 41.5, a clock can be synchronized by comparing it to a UTC reference and adjusting the time offset until it is as near zero as possible. Time transfer is the practice of transferring the time from a reference clock at one location and using it to measure or synchronize a clock at another location.
The practical analysis for closed-loop system identification
Published in Cogent Engineering, 2020
Wang Jianhong, Ricardo A. Ramirez-Mendoza
In Figure 1, is a true plant, is a noise filter, they are all stable, discrete time transfer functions, and is a monic and minimum phase. is one stable controller. The excitation signal and external disturbance or noise are uncorrelated, is a white noise with zero mean value and variance . is a colored noise, obtained by passing white noise through the noise filter . is the delay operator, it means that . Then, it holds that
Stealth identification strategy for closed loop system structure
Published in International Journal of Systems Science, 2020
Hong Wang-jian, Ricardo A. Ramirez-Mendoza
In Figure 1, is a true plant model, is a noise filter, they are all stable, discrete time transfer functions, and is a monic and minimum phase. is stable controller, whatever its linear or nonlinear forms. The excitation signal and external disturbance or noise are uncorrelated, is a white noise with zero mean value and variance . is a coloured noise, obtained by passing white noise through the noise filter . z is the delay operator, it means that and it holds that In above closed loop system structure, after some computations, we derive one transfer function form. Continuing to do some computations and we get. To simply the latter analysis process, define the sensitivity function as. Then input and output relations corresponding to the closed loop system may be rewritten as. As here our goal is to identify this closed loop system without any priori knowledge about the controller , so in next section, the identification problem is formulated and the classical prediction error identification is reviewed to solve our identification process, as the classical prediction error identification is similar to the direct approach.