Signal Phase Delay Research Articles

A New Method for Detecting Initial Position of IPMSM Rotor

Aiming at the speed sensorless control system of permanent magnet synchronous motor which embedded in rotor magnet steel, a new method for detecting the initial position of the rotor is proposed in this paper. This method is injecting a high-frequency rotating voltage to generate a high-frequency current in the stator windings that contains the spatial position information of the rotor. Compared with the traditional high-frequency injection method, this paper uses Discrete Fourier Transform (DFT) to demodulate high-frequency current. It avoids the signal phase delay caused by the use of a large number of filters when demodulating the traditional heterodyne method. At the same time, this method has nothing to do with the initial phase of the injected signal. Compared with the heterodyne method, the extracted rotor position angle is more accurate, and the structure is simple Number system. The validity and feasibility of the method are verified by simulation and experimental platform based on dSPACE.

Preseismic Ionospheric Anomalies Detected Before the 2016 Taiwan Earthquake

AbstractOn 5 February 2016 (UTC), an earthquake with moment magnitude 6.4 occurred in southern Taiwan, known as the 2016 (Southern) Taiwan earthquake and 2016 Meinong earthquake. In this study, evidences of seismic earthquake precursors for this earthquake event are investigated. Results show that ionospheric anomalies in total electron content (TEC) can be observed before the earthquake. These anomalies were obtained by processing TEC data, where such TEC data are calculated from phase delays of signals observed at densely arranged ground‐based stations in Taiwan for Global Navigation Satellite Systems. This shows that such anomalies were detected within 1 hr before the event.

コーティング式触覚センサの開発

A spray-coated tactile sensor having a simple structure which can be sprayed over complicated three-dimensional shapes such as curved surfaces is proposed. Contact points are detected as signal phase delay caused by the distributed constant RC circuit. One of the possible applications of this sensor is to spray it to the wheels of robots. In this paper, the feasibility of coating a cylindrical curved surface with the sensor is discussed. Actual sensor coated on a curved surface is verified in experiments. The principle behind the response of the looped sensor is simulated using plate sensors and examined.

コーティング式触覚センサの開発

A spray-coated tactile sensor is proposed to have a simple structure and it can be attached to complicated three-dimensional shapes such as a curved surface. This sensor detects strike points using the signal phase delay. The signal phase delay is caused by the vibration of base material or distributed constant RC circuit. In this paper, modeling a spray-coated tactile sensor is discussed. We modeled the sensor as a concentrated constant RC circuit. Finally, we succeeded in the construction of the basic model of the sensor.

Phase shift influence research of the reference oscillator signal on the output signal in homodyne demodulation scheme

Subject of Research. Important feature of homodyne demodulation method based on the arctangent function approach is the phase shift between the reference oscillator signal and the interference signal. This phenomenon is caused by propagation delays of impulses in the optical interferometric sensor scheme and the analog low-pass filter in front of the phase modulator which produces the reference oscillator signal phase delay. There is multiplying of the reference oscillator signal and the interference signal in this homodyne demodulation scheme during its processing, and the phase shift between these signals leads to a distortion of the output signal. This paper deals with the findings of the phase shift influence of the reference oscillator signal by the output signal of the demodulation scheme at various parameters of the interference signal. Estimation of required accuracy is given of the phase shift compensation for the specified level distortion of the output signal. Method. Mathematical model is proposed in MATLAB. In this model, interference signal with changing parameters by a set of rules is passed through the considered demodulation scheme. This gives the possibility to obtain the dependences of the output signal amplitude from the reference oscillator signal phase shift, the operating point of the interferometer, the depth of phase modulation and amplitude of the measured phase signal. Results obtained during the simulation showed the need to compensate the reference oscillator signal phase shift. To assess this shift in the current homodyne demodulation scheme the original method of its determination has been proposed. The method is based on the transmission of the interference signal and the oscillator signal via one and the same band-pass filter that separates the phase modulation carrier frequency. According to the phase delay between the receiving signals, the value of the reference oscillator signal phase shift can be judged on. This shift can be corrected with knowledge of the value of the reference oscillator signal phase shift. Correction is achieved by making the required delay in reference oscillator signal. Main Results. The results of mathematical modeling show significant nonlinear dependences of the output signal on the reference oscillator signal phase shift at different values of the phase modulation depth, the operating point of the interferometer and the measured phase signal amplitude. It was found out that optimal values of the reference oscillator signal phase shift equal to 0, 180 and 360 provide minimum distortions of the output signal. It was shown that to achieve about 4% distortion level of the output signal phase shift compensation with an accuracy of 3% relative to period of the reference oscillator signal was required. Practical Significance. The original method making it possible to assess the value of the reference oscillator signal phase shift has been proposed. The reference oscillator signal phase shift compensation during considered homodyne demodulation scheme practical implementation provides the correctness of the scheme operation and increases the signal to noise ratio of the output signal.

Some regularity on how to locate electrodes for higher fECG SNRs**Project supported by the National Natural Science Foundation of China (Grant No. 61271079) and the Supporting Plan Project of Jiangsu Province, China (Grant No. BE2010720).

The electrocardiogram (ECG) recorded from the abdominal surface of a pregnant woman is a composite of maternal ECG, fetal ECG (fECG) and other noises, while only the fECG component is always needed by us. With different locations of electrode pairs on the maternal abdominal surface to measure fECGs, the signal-to-noise ratios (SNRs) of the recorded abdominal ECGs are also correspondingly different. Some regularity on how to locate electrodes to obtain higher fECG SNRs is needed practically. In this paper, 343 groups of abdominal ECG records were acquired from 78 pregnant women with different electrode pairs locating, and an appropriate extended research database is formed. Then the regularity on fECG SNRs corresponding to different electrode pairs locating was studied. Based on statistical analysis, it is shown that the fECG SNRs are significantly higher in certain locations than others. Reasonable explanation is also provided to the statistical result using the theories of the fetal cardiac electrical axis and the signal phase delay.

2A1-A02 コーティング式触覚センサの試作と時間遅延を用いた位置検出原理

A spray-coated tactile sensor is proposed that has a simple structure and can be attached to complicated three-dimensional shapes such as a curved surfaces. This sensor detects strike points using the signal phase delay. In this paper, the fundamental requirements of the structure and the principle of the signal phase delay are discussed. Finally, it was found that the signal phase delay is caused by the vibration of base material or distributed constant circuit of RC with experiments.

Simulation of phase passive synchronization systems using the quadrature signal-processing

The article describes the principle of operation of the phase passive radio systems of frequency-temporal synchronization of diversity standards using the algorithm of general inclusion. The simulation provided the relations for estimates of errors and uncertainties of such systems, which are caused by the amplitude and phase distortions of signals, paths of equipment having the instability of the phase delay of signals, the ratio signal/noise. This allows you to assess the potential of the method and improve the accuracy of the frequency-temporal synchronization of geographically distributed time and frequency standards. The article also evaluated the threshold ratio signal/noise of changes described above, and presents the results of modeling of errors of phase passive synchronization systems, which are suitable for the matched filtration and correlation processing of signals in quadrature channels. The results are applicable to the algorithm of general inclusion using the signals of geostationary satellites SBAS, which emit coherent signals.

The ground GNSS tomography – unconstrained approach

The GNSS signal along its more than 20,000km line of sight is bended, attenuated and delayed. These effects are results of the Earth’s atmosphere, and Sun radiation. Amongst all mentioned effects the one considered in this paper is a signal phase delay in troposphere.This paper presents investigations in the field of GNSS ground tomography, a remote sensing technique able to capture distribution of water vapour partial pressure in the troposphere. In this method, observations are Slant Wet Delays (SWD), the phase delay of GNSS signal due to the presence of water vapour in the troposphere.One of the most important limitation in GNSS tomography is so far mandatory usage of constraints to improve design matrix rank score and in consequence the ability to obtain meaningful troposphere parameters. Solution proposed here is based on combination of SWDs from several consecutive observation epochs to increase rank score. Another important goal is to perform careful selection of singular values in the process of pseudo inverse, to limit the observation noise influence. Three different methods to select singular values are investigated: functional analysis, significant testing and L-curve fitting. The obtained results are validated by means of internal uncertainties propagation, and comparison with external model. With the simulated data the unconstrained stacked GNSS produce reliable results with uncertainties on the level of 0.3hPa in terms of water vapour partial pressure and with mean discrepancies on the level of 0.1hPa. The same measures transform to the 0.03% and 0.01% of relative error on the ground level and 100% and more, above 8km. Moreover all instabilities inside profiles were resolved properly. The simulations shows that to attain such optimistic results at least 10 observations epoch have to be stacked.

TH‐C‐BRC‐09: Tracking Moving Tumors with a Scanned Carbon Beam: Robustness to Changing Target Motion Characteristics and Tracking Uncertainties

Purpose: Beam tracking of moving tumors with scanned carbon ion radiotherapy achieves uniform target dose by adapting carbon pencil beams to follow moving tissues using real‐time lateral magnetic deflection and range modulation. The purpose of the current study was to establish the robustness of target dose coverage that can be achieved in the presence of changing target motion characteristics and uncertainties in the motion tracking system. Methods: A 4D research treatment planning system code for ion therapy was extended to compute the resulting target dose coverage when various random and systematic uncertainties were introduced to ideal tracking dose simulations. Treatment plans were prepared using the in‐ house code for a hypothetical sphere target volume with sinusoidal motion in a water phantom. Uncertainties were simulated by shifting pencil beam coordinates and modifying target motion signals. To simulate imperfect tracking, we considered variations to the following: (1) respiratory period, (2) starting respiratory phase, (3) target position drift, (4) random tracking offsets, (5) range tracking wedge acceleration, and (6) external respiratory motion signal phase delay. We also considered imperfect tracking with combinations of varying target motion characteristics and tracking uncertainties. A total of 13713 dose distributions were computed. For all cases, mean, standard deviation, minimum, and maximum of target dose were analyzed. Results: For perfect tracking of the moving sphere, mean and standard deviation of target dose were 98.2 and 0.8 % of the prescription dose, respectively. Of the variations considered, systematic drifts of target position of up to 5 mm had the most significant effect on target coverage ((6.6 ± 20.3) % decrease), and range tracking wedge accelerations above 1.0 g had the least effect on target dose ((0.0 ±1.1) %). Conclusions: The results provide insight into beam tracking precision requirements and the need to monitor and mitigate changes in patient motion.Work supported by research grant from the Deutscher Akademischer Austausch Dienst, Bonn, Germany.

A Relationship Between Phase Delay and Attenuation Due to Rain and Its Applications to Satellite and Deep-Space Tracking

We present and discuss two main results concerning the relationship between phase delay due to rain and rain attenuation, useful in calculations concerning high precision tracking of satellites and deep-space spacecrafts using interferometry techniques. We have found these two results with the Synthetic Storm Technique [SST] applied to a large data bank of rain rate time series collected at three sites in Italy. The first result concerns a formula that provides the extra signal phase delay tau (picoseconds) due to rain as a function of rain attenuation A (dB), frequency f (GHz) and slant path elevation angle thetas (degrees), given by tau = (860.4 4.82 thetas)f-1.71A0.73, for 20deg les thetas les 44deg, and by tau = 648.3 f1.71 A0.73,for 44deg les thetas les 90deg. The formula allows estimating the phase delay due to rain attenuation, with overall average (normalized) error -3%, standard deviation 11.1%, rootmean square 11.5 % for 20deg slant paths. The second result concerns a method to predict phase delay from the probability distribution of rain rate (SST probability model), very useful when only the probability distribution of rain rate is known.

An improved sensorless driving method for SRM using a phase-shift circuit technique

This paper presents an improved sensorless driving method for switched reluctance motor (SRM) using a phase-shift circuit technique. The conventional method consists of impressing short voltage pulses during unenergized phases, measuring the phase current pulses, and finding the correlation between the filtered current signals and rotor position. However, the filtering process causes a signal phase delay which varies with motor speed. This delay must be compensated for in providing the sensorless signal which is proper to the rotor position. A solution for this phase delay compensation, based on a simple analog and digital circuit, is proposed in this paper.

Investigation of chromium doped yttrium garnet spectral properties by analysis of photoacoustic signal phase delay dependence on light modulation frequency

Three samples of yttrium-aluminum garnet single crystal doped with Cr and Mg were investigated. One of them was directly as grown and two other after thermal treatment in oxygen or hydrogen atmosphere. Photoacoustic (PA) signal phase shift dependence on modulation frequency was experimentally determined for each sample under two excitation wavelengths corresponding to maximums of absorption bands. The results obtained for the two bands were compared and analyzed using a basic or extended theory of PA signal generation. It have been shown that the PA signal phase dependence on modulation frequency is a good indicator for modification of the Cr ion centers due to the crystal thermal processing .