Amplitude Of Sinusoidal Signal Research Articles

ОСОБЛИВОСТІ ПОБУДОВИ ІМПЕДАНСОМЕТРИЧНИХ КАНАЛІВ ДЛЯ РОБОТИ НА НИЗЬКИХ ТА ІНФРАНИЗЬКИХ ЧАСТОТАХ

The features of the low and infra-low frequency ranges of harmonic measurement signals, as well as the properties of the investigated objects, which must be taken into account during the construction of impedance measuring channels, are determined. To combine the necessary metrological characteristics of such channels (accuracy, speed, immunity), an approach is used, consisting in analog-to-digital conversion of signals received from sensors, and subsequent application of digital methods of their processing. Options for implementing this approach using digital methods for determining the amplitude of sinusoidal signals were considered and analyzed, among which the most promising ones were selected for metrological support of impedance measurements at low and infra-low frequencies. The perspective of using parallel-serial analog-digital conversion of an informative signal with its continuous integration at these frequencies is shown. Conclusions were made and recommendations were given regarding the use of the considered methods taking into account the properties of the measurement objects. References 16.

Block-MUSIC in blade tip timing: Performance study of block snapshot matrix

Periodic nonuniform sampling can be viewed as a combination of uniform sampling and non-uniform sampling. Blade tip timing (BTT) technique conforms to this sampling pattern, where non-uniformity and uniformity are caused by non-uniform probe layout and rotational motion, respectively. By introducing block structure into multiple signal classification (MUSIC) for the extension of snapshot matrix, Block-MUSIC has been proved to be anti-aliasing and can filter out synchronous frequency in BTT application. However, the theoretical justification of the block structure is lacking. In this paper, a performance study of Block-MUSIC is conducted from three aspects: identifiability, stability, and resolution. Additionally, a pseudo 2-dimensional signal model is proposed to represent the periodic nonuniform sampled signal under the assumption of equally spaced probes. To support the performance study, simulations and experiments are carried out to demonstrate how the size of the snapshot matrix, the noise level, and the amplitude of sinusoidal signals affect algorithm performance. Simulation codes are available at https://github.com/superjdg/block-music4btt.

МІНІМІЗАЦІЯ ВИПАДКОВОЇ ПОХИБКИ ЦИФРОВОГО МЕТОДУ ВИМІРЮВАННЯ АМПЛІТУДИ СИНУСОЇДАЛЬНОГО СИГНАЛУ

The errors of measuring the amplitude of sinusoidal signals by the method based on calculating the sum of the ratios of digital samples of instantaneous signal values to the sines of the phase angles corresponding to the sampling moments are investigated. A mathematical expression for determining the total random measurement error using the values of the parameters of the error components is obtained. It is shown that there is a minimum value of the total random measurement error as a function of the number of instantaneous signal values taken into account. The method of reducing the level of random error to the desired level is given. The method can be used to create metrological support for measuring the parameters of electrical signals at low and infralow frequencies, including industrial frequency. Ref. 7, fig. 4, table.

Modeling and Adaptive Design of the SRF-PLL: Nonlinear Time-Varying Framework

Synchronous reference frame phase-locked loops (SRF-PLLs) are widely used in different technologies, such as wind turbines, electric vehicles, more electric aircraft, and motor drives, to estimate system's variables. The SRF-PLL is an adaptive notch filter that is used to estimate a sinusoidal signal's amplitude, phase angle, and frequency. However, when the input signal is subjected to a considerable variation or includes a significant noise, its stability and performance become challenging. In this paper, the stability of the SRF-PLL for substantial changes in the input signal's variables are investigated. To do so, the nonlinear time-varying (NTV) model of the system is proposed and is used for the large-signal stability assessment. Then, an adaptive tuning method, based on the proposed NTV model, is designed to improve its transient performance during and after the variation. Simulation and experimental results are used to validate the proposed method.

Broadband Enhancement of Optical Frequency Comb Using Cascaded Four-Wave Mixing in Photonic Crystal Fiber

A cascaded intensity modulator (IM) and phase modulator (PM) are used to modulate a continuous-wave (CW) laser and generate an optical frequency comb (OFC). Thus, the generated comb is utilized as an initial seed and combined with another CW-laser to generate four-wave mixing (FWM) in photonic crystal fiber (PCF). Results show that an initial flat 30 GHz OFC of 29, 55 lines within power fluctuation of 0.8 dB and 2 dB, respectively, can be achieved by setting the ratio of the DC bias to amplitude of sinusoidal signal at 0.1 and setting the modulation indices of both IM and PM at 10. Moreover, the 1st order of FWM created through 14 m of PCF has over 68 and 94 lines with fluctuation of 0.8 dB and 2 dB, respectively. Hence, the generated wavelengths of 1st left and right order of FWM can be tuned in a range from ~1500 nm to ~1525 nm and ~1590 nm to ~1604 nm, respectively.

A Method of m-Point Sinusoidal Signal Amplitude Estimation

Abstract The paper presents a new and original method of m-point estimation of sinusoidal signal amplitude. In this method, an m-point estimator is calculated on the basis of m initial signal samples. The way the estimator is constructed is explained. It is shown that the starting point for constructing the estimator is two initial signal samples. Next, in order to determine the estimator general form, three and m subsequent initial signal samples appearing in a signal period are used. Some special cases of an estimator are considered. Such an estimator is compared with a four-point estimator proposed by Vizireanu and Halunga. It is shown that the m-point estimator makes it possible to estimate the signal amplitude more accurately.

Nonlinear Stability Prediction of Multibit Delta–Sigma Modulators for Sinusoidal Inputs

This paper proposes a novel algorithm that can be integrated with various design and evaluation tools, to more accurately and rapidly predict stability in multibit delta-sigma (Δ-Σ) modulators. Analytical expressions using the nonlinear gains from the concept of modified nonlinearity in control theory are incorporated into the mathematical model of multibit Δ-Σ modulators to predict the stable amplitude limits for sinusoidal input signals. The nonlinear gains lead to a set of equations, which can numerically estimate the quantizer gain as a function of the input sinusoidal signal amplitude. This method is shown to accurately predict the stable amplitude limits of sinusoids for second-sixth-order three- and five-level midtread quantizer-based Δ-Σ modulators. The algorithm is simple to apply and can be extended to midrise quantizers or to any number of quantizer levels. The only required input parameters for this algorithm are the number of quantizer levels and the coefficients of the noise transfer function.

Electrochemical characterization of a primary electrolytic conductivity cell at CENAM

Linear voltammetry and electrochemical impedance spectroscopy experiments were performed in order to obtain basic information about the electrochemical behavior of the primary cell of electrolytic conductivity at Centro Nacional de Metrologia. Linear voltammetry shows that the amplitude of the sinusoidal perturbation must be smaller than 300 mV. Electrochemical impedance results indicate that optimal frequency interval extends from 5 to 0.6 kHz. Regarding sinusoidal signal amplitude, a lower bias with respect to electrolytic conductivity of an independent reference solution is obtained at 10 mV than at larger amplitudes; in addition, electrode integrity is improved.

Architecture for instantaneous frequency and amplitude detection

This paper presents a new architecture to detect the frequency and amplitude of sinusoidal signals. The proposed architecture employs merely differentiators and analog computational units to gain an accurate and instantaneous response. The detected output of the frequency measuring module is linear with frequencies and insensitive to the peak amplitude of the input signal, and vice versa. Moreover, the sensitivity (gain) of frequency detection module and that of amplitude detection module are orthogonally adjusted. The simulation results are then given to verify the theoretical analyses. The results also include various set of simulation aiming to give substantive measures of satisfactory performance of the proposed method.

Short time measurement of frequency and amplitude in the presence of noise

A method for the measurement of amplitude and frequency of sinusoidal signals in the presence of noise during a few periods is proposed. The method presented gives one the possibility to make measurement of frequency and amplitude of sinusoidal signals without noise during a very short time (less than a half period) and in the case of signals corrupted by noise (during only two periods) with sufficiently acceptable results. The theoretical basis, several measurement algorithms and selected results of computer simulation are presented. The performance is compared to that of known methods. >

Improving the accuracy of sinusoidal signal amplitude meters

Improving the accuracy of sinusoidal signal amplitude meters

Analysis of systematic errors in the determination of noise immunity of computing hardware

The following conclusions can be drawn from the above discussion. The error in measuring signal parameters with the aid of a sampling oscilloscope depends on the noise in horizontal and vertical deflection channels. Application of the histogram method gives simple algorithms for measuring certain parameters of pulse and sinusoidal signals and makes it possible to eliminate the effect of the horizontal channel noise on the results of measurement. Vertical deflection channel noise is a source of a systematic error in the measurement of sinusoidal signal amplitude by the histogram method. This error can be calculated and eliminated as proved by experimental measurements carried out with the $9-9 precision sampling oscilloscope.

A method for fast amplitude detection of variable period sinusoidal signals

Abstract In this work a method for fast detection of sinusoidal signal amplitude of variable period is proposed. Information for the signal amplitude is taken with several sample pulses in each half period with the aid of a multiplier and a differentiator. The sampled signal values are held and equalized with the signal amplitude by a weighting amplifier.

A 90-degree phase difference network for circular display of the EEG on a cathode ray tube

For sonic analysis methods, which are mainly used for the study of rhythmic phenomena in the EEG, timing pulses have to be available at comparable time points of the analysed signal. Turton (1952) and Bekkering and Storm van Leeuwen (1954) described a method for generating such pulses to trigger a photic stimulator. Timing pulses are also used in the method of automatic auto- and cross-relation analysis described by Kamp et al. (1965), and are generated by means of a modification of the m~ ~thod described by Turton. According to Turton's method, by means of a Lissajous figure, the EEG is displayed circularly on the screen of a cathode ray tube. A photo-electric device is placed on the screen of the tube and in this way a pulse is obtained whenever the spot passes the photo-electric device. The advantage of the method is that the occurrence of the timing pulses is independent to a certain degree of the amplitude of sinusoidal signals. The same applies to non-sinusoidal rhythmic signals if their wave form does not change. To obtain the circular display the signal is conducted to the horizontal and vertical deflection systems of the cathode ray tube with a 90 ° phase difference. The 90 ° phase difference is obtained only for signals within a certain frequency range and for automatic auto- and cross-relation the range of Turton's network is too limited. For this reason a 90 ° phase differen~ network described by Villard (1952), which has a wider frequency range, has been modified. This network was used for signals within the audio frequency range. By change of values of the frequency determining components the network may be used also within the EEG frequency range. A diagram of the network is shown in Fig. 1. The complete network consists of two bridge circuits A and B which have the cathode follower output stages Ta and T4. The output amplitudes of the two bridge circuits are independent of the frequency of the input signal. This is not the case with the input-output phase relations. However, within a limited frequency range an approximation