Frequency Jitter Research Articles

A DDS-Based Wait-Free Phase-Continuous Carrier Frequency Modulation Strategy for EMI Reduction in FPGA-Based Motor Drive

In ac motor drives, the fixed-frequency harmonic components of output voltage and current from the inverter with fixed-frequency pulsewidth modulation usually lead to electromagnetic interference (EMI). The spread spectrum clock generation (SSCG) is a widely used solution for this problem. Adjusting the switching frequency to reduce EMI is one kind of practicable scheme among SSCG methods. How to design an optimal or suitable modulation profile is a research emphasis of scholars and has been discussed in depth in many literatures. However, apart from the modulation profile, the mode and quality of carrier are also important and can be improved. In most frequency modulation methods, due to the limitation of the conventional carrier generation mode, the implementation of the new frequency instruction has to wait for the termination of the last switching period. In order to eliminate the waiting state and design a simpler algorithm, this paper has proposed a wait-free phase-continuous carrier frequency modulation (WPCFM) strategy by combining the direct digital frequency synthesizer theory and proper temporal planning of control interruptions. Besides, a theoretical analysis of WPCFM, including quantization error, frequency jitter, phase delay, and voltage distortion, has been finished. Moreover, compared with conventional methods, a more convenient, feasible, and simpler field-programmable gate array based algorithm implementation method and the control structure of WPCFM are also introduced. The analysis shows that, although WPCFM causes a slight increase of the current ripple, it can solve the partial frequency nonuniform distribution problem of the conventional method, and it has a potential value of applications in the wide band gap motor drive systems. The effectiveness of the WPCFM is verified by several sets of EMI reduction experiments where classical periodic carrier frequency modulations are applied.

Effect of Omaha system measures combined with voice training in the treatment of patients with functional vocal dyspraxia caused by glottic insufficiency

Objective To explore the effect of Omaha system combined with voice training in the treatment of patients with functional vocal dyspraxia caused by incomplete glottic closure. Methods From January 2017 to December 2017, eighty-eight patients with vocal dystonia due to glottic insufficiency who were treated in the Second Hospital of Shaoxing were randomly divided into control group and observation group by random number table method, with 44 cases in each group.The control group was treated with voice training.The observation group was given Omaha system measures on the basis of treatment in the control group.After 8 weeks, the therapeutic effects, GRBAS index scores, VHI scores, changes in acoustic parameters, and laryngoscope scores were compared between the two groups. Results After treatment, the total effective rate of the observation group (90.91%) was significantly higher than that of the control group(59.09%)(χ2=9.317, P<0.05). After treatment, the scores of total deafness, roughness and other indicators were significantly reduced in both two groups, and the scores of GRBAS in the observation group were significantly lower than those in the control group(t=8.674, P<0.001; t=2.169, P=0.032; t=2.489, P=0.014; t=32.832, P<0.001; t=9.381, P<0.001). After treatment, the index scores and total VHI scores of both two groups were significantly decreased, and the scores of the observation group were significantly lower than those of the control group(t=2.222, P=0.028; t=3.144, P=0.002; t=2.003, P=0.048; t=5.763, P<0.001). After treatment, the maximum phonation time(MPT), basic frequency(Jitter), and lowest sound intensity(I-Low) were significantly reduced in the two groups, which in the observation group were significantly lower than those in the control group(t=4.037, P<0.001; t=4.789, P<0.001; t=4.717, P<0.001). The highest basic frequency(F0-High) and DSI index significantly increased in both two groups, which in the observation group were significantly higher than those in the control group(t=4.497, P<0.001; t=4.794, P<0.001). Conclusion The combination of Omaha system measures and voice training can significantly improve functional vocal disturbances caused by glottic insufficiency, significantly improve the quality of patients' voices, improve glottic closure, and contribute to the recovery of patients' voices.It is worthy of promotion in clinical practice. Key words: Omaha system measures; Vocal training; Glottic insufficiency; Functional vocal disturbance; Therapeutic effect; Vocal disorder severe index; Acoustics; Vocal

Effect of CO2 laser assisted laryngoscope on glottic carcinoma

Objective To prospectively investigate laryngoscopy-assisted CO2 laser in the treatment of glottic laryngeal carcinoma. Methods 97 patients with early glottic laryngeal carcinoma in our hospital were selected and divided into control group (n=48) and observation group (n=49) according to random number table. The control group was treated with partial laryngectomy and the observation group was treated with laryngoscopy-assisted CO2 laser. The clinical efficacy, serum level of α1-acid glycoprotein (α1-AG) and ceruloplasmin (CER) after 10 min of the surgery and changes of the indicators of voice function [fundamental frequency jitter (jitter), the longest sound time (MPT), sound pressure level (SPL)] were observed and compared between the two groups, and the incidence of complications and quality of life (QOL) scores were statistically compared. Results The total remission rate in the observation group was 79.59% (39/49) , which was higher than that in the control group 56.25% (27/48), with statistically significant difference (χ2=6.075, P=0.014). The levels of serum α1-AG and CER in the observation group 10 min after surgery were lower than those in the control group, with statistically significant difference (t=2.641, P=0.010, t=31.242, P=0.000). From 2 weeks after surgery to 3 months after surgery, SPL and MPT of two groups decreased first and then increased; Jitter increased first and then decreased, and the changing amplitude in the observation group was smaller than that in the control group, with statistically significant difference (P<0.05). The incidence of complications in the observation group was 2.04% (1/49), which was lower than that in the control group 16.67% (8/48), with statistically significant difference (P<0.05); 3 months after surgery, the QOL score of the observation group was higher than that of the control group, with statistically significant difference (P<0.05). Conclusions Supporting laryngoscope CO2 laser surgery can improve stress state and quality of life of early glottic laryngeal cancer patients, and the incidence of complications is low. It has little effect on voice function. Key words: Laryngeal neoplasms; Glottis; Laryngoscopy; Laser therapy; Lasers, gas

SYSTEMATIC GEOMETRIC IMAGE ERRORS OF VERY HIGH RESOLUTION OPTICAL SATELLITES

Abstract. Very high resolution optical satellites are imaging the object space by a combination of CCD-lines in one direction and by time, speed and satellite rotation in the other direction. The combination of the CCD-lines usually is known by pre-calibration. Remaining errors of the pre-calibration, also slightly depending upon the satellite movement and rotation, with few exceptions are usually small up to negligible. This may not be the case for the image component in the scan direction and the alignment of the line combinations - they are controlled by giros and stellar cameras. Stellar cameras are compensating giro drifts, but their recording frequency is limited as well as in general the accuracy of the satellite view direction. In addition the satellites may show a jitter caused by the fast rotation from one pointed area to another. Not all giros are able to record the jitter frequency. A limited accuracy of the view direction is causing systematic image errors in relation to the used mathematical model of geometric reconstruction. The systematic image errors can be determined theoretically by image orientation based on ground control points (GCPs), but usually not a satisfying number and distribution of GCPs is available. Another possibility is the analysis of the intersection of corresponding rays in a stereo model and an analysis of generated height models against reference height models. Here also free of charge available height models as the SRTM Digital Surface Model (DSM) or AW3D30 can be used. Several very high resolution satellite cameras have been analyzed; this includes images from WorldView-2, WorldView-4, Kompsat-3, Kompsat-1, Pleiades, Cartosat-1, ZY3, OrbView-3, QuickBird, IKONOS, ASTER, IRS-1C, SPOT, SPOT-5 HRS, EROS-B, IKONOS, QuickBird, OrbView and GeoEye but only results of the today more important satellites are shown in detail. For few satellites the systematic image errors can be ignored, but others require a correction which may be just a levelling of the DSM but also a higher degree of deformation up to a compensation of the satellite jitter effect. The used method cannot be named as calibration due to variation from image to image, only the character and size of deformation is typical for the used special optical satellite, but it depends also upon the operating conditions as fast satellite rotation. Due to the very high number of reference points in a DSM the determination of systematic image errors is independent upon random errors and also high frequent jitter can be determined with a standard deviation down to 0.1 ground sampling distance (GSD) or even better.

Robust solving of optical motion capture data by denoising

Raw optical motion capture data often includes errors such as occluded markers, mislabeled markers, and high frequency noise or jitter. Typically these errors must be fixed by hand - an extremely time-consuming and tedious task. Due to this, there is a large demand for tools or techniques which can alleviate this burden. In this research we present a tool that sidesteps this problem, and produces joint transforms directly from raw marker data (a task commonly called "solving") in a way that is extremely robust to errors in the input data using the machine learning technique of denoising. Starting with a set of marker configurations, and a large database of skeletal motion data such as the CMU motion capture database [CMU 2013b], we synthetically reconstruct marker locations using linear blend skinning and apply a unique noise function for corrupting this marker data - randomly removing and shifting markers to dynamically produce billions of examples of poses with errors similar to those found in real motion capture data. We then train a deep denoising feed-forward neural network to learn a mapping from this corrupted marker data to the corresponding transforms of the joints. Once trained, our neural network can be used as a replacement for the solving part of the motion capture pipeline, and, as it is very robust to errors, it completely removes the need for any manual clean-up of data. Our system is accurate enough to be used in production, generally achieving precision to within a few millimeters, while additionally being extremely fast to compute with low memory requirements.

A new adaptive bandwidth, adaptive jitter frequency synthesizer using programmable charge pump circuit

A new adaptive bandwidth, adaptive jitter frequency synthesizer is proposed. This synthesizer is designed in such a way that the ratio of bandwidth to the reference frequency is kept approximately fixed in order to maintain the optimum jitter performance. The proposed structure employs a novel programmable charge pump and a charge pump controller circuit. Regarding the control voltage of the LC voltage controlled oscillator (VCO), the charge pump controller determines the output sink/source current of the charge pump and maintains the ratio of the charge pump current to the VCO oscillation frequency fixed. It is shown that using this idea and proposed building blocks, variations of the desired ratio of the bandwidth to the reference frequency are canceled and thus, the optimum output jitter manner of the frequency synthesizer is preserved. The proposed structure is simulated in 0.18 µm CMOS technology and simulation results are presented and discussed.

The Development of Phasemeter for Taiji Space Gravitational Wave Detection

Taiji space gravitational wave detection utilizes the laser interferometer to convert the tiny distance change into the phase fluctuation of the beat note. As to realize the sensitivity of 1 pm/√ Hz, the phasemeter needs to calculate the phase with the precision of 2πμ rad/√ Hz in the frequency range of 0.1 mHz and 1 Hz. In this paper, we report recent progress of the phasemeter for Taiji. Noises which possibly affect the measurement sensitivity are tested and discussed, especially the sampling noise and the frequency jitter. Finally, the accuracy of the phasemeter is calibrated. The result shows that the sensitivity has reached the requirement of Taiji in the frequencies between 0.01 Hz and 1 Hz, 0.1 mHz–1 mHz. Noises in the range of 1 mHz and 0.01 Hz, which have not yet depressed well, are dominated by the clocking jitter and the thermal fluctuation.

Development of an injection-seeded single-frequency laser by using the phase modulated technique**Project supported by the National Key Research and Development Program of China (Grant Nos. 2017YFB1104500 and 2016YFB0701000).

An injection-seeded single-frequency Q-switched Nd:YAG laser is accomplished by using a phase modulated ramp-fire technique. A RbTiOPO4 (RTP) electro-optic crystal is selected for effective optical path length modulation of the slave self-filtering unstable resonator. This single-frequency laser is capable of producing 50 mJ pulse energy at 1 Hz repetition rate with a pulse width of 16 ns. The standard deviation of laser pulse intensity for consecutive 100 shots from the mean pulse intensity is less than 1.05%. A spectral linewidth of less than 0.5 pm with a frequency jitter of about 14 fm over 30 min is obtained.

Scanning Rayleigh Doppler Lidar for Wind Profiling Based on Non-polarized Beam Splitter Cube Optically Contacted FPI

A Scanning Rayleigh Doppler lidar for wind profiling based on a non-polarized beam splitter cube optically contacted FPI is developed for wind measurement from high troposphere to low stratosphere in 5-35 km. Non-polarized beam splitter cube optically contacted to the FPI are used for a stable optical receiver. Zero Doppler shift correction is used to correct for laser or FPI frequency jitter and drift and the timing sequence is designed. Stability of the receiver for Doppler shift discrimination is validated by measuring the transmissions of FPI in different days and analyzed the response functions. The maximal relative wind deviation due to the stability of the optical receiver is about 4.1% and the standard deviation of wind velocity is 1.6% due to the stability. Wind measurement comparison experiments were carried out in Jiuquan (39.741°N, 98.495°E), Gansu province of China in 2015, showing good agreement with radiosonde result data. Continuous wind field observation was performed from October 16th to November 12th and semi-continuous wind field of 19 nights are presented.

Optical frequency linked dual-comb absorption spectrum measurement

Dual-comb spectroscopy is becoming a highlighted topic in broadband spectrum measurement techniques because of two outstanding advantages. One is its highly stable output frequency, which leads to an appealing resolution, and the other is the omitting of moving parts, which helps achieve extreme fast sampling rate. Utilizing the traditional radio frequency linked combs, however, obstructs the dual-comb spectroscopy reaching satisfied performance because the phase noise of the radio frequency standard causes the dual-comb mutual coherence to severely degrade. Specifically, traditional frequency comb stabilizes the carrier envelope offset at a radio frequency by a self-reference system, and the order number of each output comb tooth is over a hundred thousand. Thus, the phase noise of the radio frequency reference is significantly multiplied in output optical frequency by the same order of magnitude as the tooth order number. In this paper, we demonstrate an optical frequency linked dual-comb spectrometer where the two combs are locked to a common narrow linewidth laser. In this configuration, the two combs are synchronized at an identical optical frequency, which means that the carrier envelope offset of the two combs are changed to an optical frequency and the order number of the output comb teeth are reduced by two orders of magnitude. Therefore, not only the complex and costly self-reference system can be removed but also the phase noise of the optical frequency of each comb tooth is effectively reduced, which leads to lower mutual frequency jitters and better mutual coherence. To prove the performance, we measure the 1+3 P branch of 13C2H2 molecular and the results accord well with the reported line positions and reveals a spectral resolution of 0.086 cm-1. The average signal-to-noise ratio exceeds 200:1 (62.5 ms, 100 times on average) and the noise equivalent coefficient is 6.0106 cm-1Hz-1/2. This work provides a solution for pragmatic dual-comb spectroscopy with high resolution and low-cost configuration.

Strongly Coherent Single-Photon Emission from Site-Controlled InGaN Quantum Dots Embedded in GaN Nanopyramids

Group III-nitride materials have drawn a great deal of renewed interest due to their versatile characteristics as quantum emitters including room-temperature operation, widely tunable wavelengths from ultraviolet to infrared, and a high degree of linear polarization. However, most reported results for III-nitride-based quantum emitters show large inhomogeneous line width broadening in comparison to their lifetime-limited values, which is detrimental to achieving indistinguishability with high visibility. To overcome this, we propose an unprecedented InGaN quantum dot formation technique at the apex of GaN nanopyramid structures, which significantly suppresses inhomogeneous line width broadening. Using high-resolution transmission electron microscopy, a site-controlled InGaN quantum dot with small height (<2 nm) was estimated. No measurable screening effect or frequency jitter of the single-photon emission was observed, which leads to the narrow homogeneous emission line width (64 ± 8 μeV) beyond the spect...

A frequency multiplier for reference frequency in frequency synthesizer systems

A low jitter frequency multiplier, which requires less power, area, and design complexity than reference multiplying PLL or DLL circuits can be used to generate the reference frequency for a low phase noise frequency synthesizer. This paper proposes a mixed signal solution based on the fact that the average DC value of a signal is proportional to its duty cycle. The solution uses a feedback loop with coarse and fine delay resolution to generate a $$90^{\circ }$$ phase shifted clock that is used to produce a doubled frequency signal with 50% duty cycle. This method can be used to multiply the input frequency of 40 MHz by multiples of 2, up to 16. The design is implemented in 65 nm UMC CMOS process. Operating from 1.2-V supply, it dissipates 0.46 to 1.2 mA at output frequencies 80–640 MHz, achieving − 162.3 and − 139 dBc/Hz phase noise at 1 MHz offset, respectively.

Temporal Stability and Spectral Accuracy Enhancement of the Spectro-Temporal Analyzer

The advent of the time-stretch technology, together with the high-speed photodetector, enables ultrafast spectrum analysis in the form of spectro-temporal analyzer, such as the amplified dispersive Fourier transform (ADFT) and the parametric spectro-temporal analyzer (PASTA). Leveraging the MHz to GHz frame rate, such a spectro-temporal analyzer is capable of observing certain ultrafast or non-repetitive events, such as the birth of mode-locking. However, since it always requires a large amount of dispersion, the spectral accuracy will be greatly degraded by the temporal instability, including the temperature-induced timing jitter and the cavity-induced frequency jitter, which hinder the practical application of such an ultrafast spectroscopy technique. To enhance the temporal stability and thereby spectral accuracy, two active control schemes are introduced here: the temperature feedback control for the long fiber link, and the phase-locked loop for the short laser cavity. As a result, the temporal stability is greatly enhanced, and the spectral accuracy is improved from 1.6 to 0.04 nm over a 5-h period of time. This stabilization process is an essential step for the practical application of spectro-temporal analyzers, such as the ADFT and particularly the PASTA.

Vocal assessment of addicts on methadone therapy via the RBH scale and objective acoustic parameters

IntroductionA large number of people around the world struggle daily to become free of their addiction to illegal psychoactive substances. In order to create an atmosphere of improved supervision, established communication and improved quality of life for drug addicts, centers have been set up to provide methadone as a substitute. ObjectiveThe aim of the research was to assess the vocal features of drug addicts on methadone therapy via subjective and objective parameters, to ascertain if vocal damage has occurred and to determine whether subjective and objective acoustic vocal parameters are related, and how. MethodsThe research included 34 adults of both genders who were undergoing methadone treatment. A subjective vocal evaluation assessed voice pitch and clarity, while the subjective acoustic analysis utilized the Roughness-Breathiness-Hoarseness scale of roughness-breathiness-hoarseness. Objective acoustic analysis was conducted after recording and analyzing an uninterrupted vocal /a/ of at least three seconds duration, using the “GllotisController” software. ResultsThe subjective acoustic analysis using the Roughness-Breathiness-Hoarseness scale showed pathological values in 52.9% male and 47% female participants. The average values of the roughness-breathiness-hoarseness for the entire sample were 0.91, 0.38 and 0.50, respectively. Lower roughness was associated with a higher fundamental frequency (f0) and lower jitter and shimmer values (p<0.05). There was a statistically significant correlation between breathiness, jitter (p<0.01) and shimmer (p<0.05), and between hoarseness and jitter (p<0.01). ConclusionA statistically significant correlation was found between the two subjective vocal assessments, voice clarity and pitch, and Roughness-Breathiness-Hoarseness scale, and the parameters of the objective acoustic vocal assessment.

Speckle pattern sequential extraction metric for estimating the focus spot size on a remote diffuse target.

The speckle pattern (line by line) sequential extraction (SPSE) metric is proposed by the one-dimensional speckle intensity level crossing theory. Through the sequential extraction of received speckle information, the speckle metrics for estimating the variation of focusing spot size on a remote diffuse target are obtained. Based on the simulation, we will give some discussions about the SPSE metric range of application under the theoretical conditions, and the aperture size will affect the metric performance of the observation system. The results of the analyses are verified by the experiment. This method is applied to the detection of relative static target (speckled jitter frequency is less than the CCD sampling frequency). The SPSE metric can determine the variation of the focusing spot size over a long distance, moreover, the metric will estimate the spot size under some conditions. Therefore, the monitoring and the feedback of far-field spot will be implemented laser focusing system applications and help the system to optimize the focusing performance.

Stability of period-one (P1) oscillations generated by semiconductor lasers subject to optical injection or optical feedback.

We study the stability of period-one (P1) oscillations experimentally generated by semiconductor lasers subject to optical injection (OI) and by those subject to optical feedback (OF). With unique advantages of broad frequency tuning range and large sideband rejection ratio, P1 oscillations can be useful in applications such as photonic microwave generation, radio-over-fiber communication, and laser Doppler velocimeter. The stability of the P1 oscillations is critical for these applications, which can be affected by spontaneous emission and fluctuations in both temperature and injection current. Although linewidths of P1 oscillations generated by various schemes have been reported, the mechanisms and roles which each of the OI and the OF play have however not been investigated in detail. To characterize the stability of the P1 oscillations generated by the OI and the OF schemes, we measure the linewidths and linewidth reduction ratios (LRRs) of the P1 oscillations. The OF scheme has a narrowest linewidth of 0.21 ± 0.03 MHz compared to 4.7 ± 0.6 MHz in the OI scheme. In the OF scheme, a much larger region of LRRs higher than 90% is also found. The superior stability of the OF scheme is benefited by the fact that the P1 oscillations in the OF scheme are originated from the undamped relaxation oscillation of a single laser and can be phase-locked to one of its external cavity modes, whereas those in the OI scheme come from two independent lasers which bear no phase relation. Moreover, excess P1 linewidth broadening in the OI scheme caused by fluctuation in injection parameters associated with frequency jitter and relative intensity noise (RIN) is also minimized in the OF scheme.

A New Coherent Integration Method for Frequency Jittering Radar

For the frequency jittering radar, the problems of range migration and phase jittering among different pulses may occur during the long-time integration, which will affect the target energy integration. Therefore, a new coherent integration algorithm, namely, Frequency jittering based Radon-Fourier transform (FJ-RFT), is proposed. Based on jointly searching in the motion parameter space, the problems mentioned above can be simultaneously resolved and the coherent integration can be then realized. The Cramer-Rao lower bound (CRLB) and the Blind speed sidelobes (BSSL) of the proposed FJ-RFT are analyzed in detail. Finally, numerical experiments are provided to demonstrate the effectiveness of the proposed method.

PR-based SAR reconstruction algorithm for phase noise mitigation based on the hidden convexity

The performance of synthetic aperture radar (SAR) reconstruction is significantly deteriorated by the random phase noises arising from the atmospheric turbulence or frequency jitter of the transmit signal. Recently, the emerging phase retrieval (PR) technique is gradually extended to the SAR reconstruction problem via the phase-corrupted data attributing to its alluring potential for phase noise mitigation. In this paper, a novel PR-based SAR reconstruction algorithm for phase noise mitigation is proposed by jointing alternating direction method of multipliers (ADMM) and Kolmogorov spectral factorization (KoSF). Owing to the exploiting of the hidden convexity of PR-based SAR reconstruction problem and the structure advantage of the quadratic magnitude measurement, the proposed algorithm acquires better robustness for the complex-valued Gaussian white noises and the random phase noises than the existing PR-based SAR reconstruction algorithms. In the experiments, the synthetic scene data and the moving and stationary target recognition Sandia laboratories implementation of cylinders (MSTAR SLICY) target data are provided to verify the validity of the proposed algorithm.

Detection and Estimation of Along-Track Attitude Jitter From Ziyuan-3 Three-Line-Array Images Based on Back-Projection Residuals

High-resolution satellite images (HRSIs) obtained from linear array charge-coupled device sensors always suffer from geometric instability in the presence of attitude jitter. Therefore, detection and compensation of spacecraft attitude jitter in both the cross-track and along-track directions are crucial to improve the geometric accuracy of HRSIs. A number of reports have been made on the detection and estimation of cross-track attitude jitter. However, the detection of the attitude jitter in the along-track direction is more complicated due to the impact of topographic change. This paper presents a novel approach to achieve accurate estimation of the along-track attitude jitter by eliminating the influence of topographic information based on the back-projection residuals of three-line-array (TLA) images. The principle of detection and estimation of along-track attitude jitter is described, and the proposed approach consists of three main components as follows: 1) dense image matching of the TLA images using a comprehensive matching strategy; 2) detection of the back-projection residuals in the line direction caused by attitude jitter; and 3) estimation of the along-track attitude jitter from the back-projection residuals using a genetic algorithm. Experiments were conducted using China’s Ziyuan-3 (ZY-3) TLA images, and the experimental results reveal that the frequency of the attitude jitter in the along-track direction ranges between 0.6 and 0.7 Hz, which is consistent with the frequency in the cross-track direction observed in our previous study. In addition, a comparison of the results of the proposed approach with those from direct attitude observations shows good consistency, with as little as 0.1-pixel disparity, which demonstrates the feasibility and reliability of the proposed approach. Furthermore, the geometric accuracy is further improved from a pixel level to a subpixel level and the periodic trend is removed with the compensation of the estimated attitude jitter in addition to the conventional affine compensation, which validates the potential of the proposed approach for geometric accuracy improvement with ZY-3 TLA images.

Illusory Jitter Perceived at the Frequency of Alpha Oscillations

Neural oscillations, such as alpha (8-13Hz), beta (13-30Hz), and gamma (30-100Hz), are widespread across cortical areas, and their possible functional roles include feature binding [1], neuronal communication [2, 3], and memory [1, 4]. The most prominent signal among these neural oscillations is the alpha oscillation. Although accumulating evidence suggests that alpha oscillations correlate with various aspects of visual processing [5-18], the number of studies proving their causal contribution in visual perception is limited [11, 16-18]. Here we report that illusory visual vibrations are consciously experienced at the frequency of intrinsic alpha oscillations. We employed an illusory jitter perception termed the motion-induced spatial conflict [19] that originates from the cyclic interaction between motion and shape processing. Comparison between the perceived frequency of illusory jitter and the peak alpha frequency (PAF) measured using magnetoencephalography (MEG) revealed that the inter- and intra-participant variations of the PAF are mirrored by an illusory jitter perception. More crucially, psychophysical and MEG measurements during amplitude-modulated current stimulation [20] showed that the PAF can beartificially manipulated, which results in a corresponding change in the perceived jitter frequency. These results suggest the causal contribution of neural oscillations at the alpha frequency in creating temporal characteristics of visual perception. Our results suggest that cortical areas, dorsal and ventral visual areas in this case, are interacting at the frequency of alpha oscillations [2, 3, 21-27].