IEEE open journal of ultrasonics, ferroelectrics, and frequency control最新文献

{"title":"Flicker Suppressed Direct Digital Phase and Amplitude Noise Measurements","authors":"Marco Pomponio;Archita Hati;Craig W. Nelson","doi":"10.1109/OJUFFC.2026.3672064","DOIUrl":"https://doi.org/10.1109/OJUFFC.2026.3672064","url":null,"abstract":"In this article, we present a new and innovative technique that reduces the close-to-the-carrier noise floors in direct digital measurement systems. For a 100 MHz carrier, with respect to our previous state-of-the-art direct digital measurement system, we report a noise floor reduction of over 35 dB in the flicker region for both phase and amplitude noise, and greater than a factor of 20 improvement in Allan deviation. Moreover, this technique reduces the impact of analog-to-digital converter’s voltage reference noise and aperture jitter on the system noise floor, allowing the construction of multichannel systems for timescale applications while maintaining the same performance levels. We call this new method flicker-suppressed direct digital. At 100 MHz for a single channel, we report single sideband residual phase noise floor of <inline-formula> <tex-math>$mathscr {L}left ({{1 text {Hz}}}right) ~text {=} -147 text {dBc/Hz}$ </tex-math></inline-formula>, with a flicker corner of about 0.03 Hz. The single channel residual Allan deviation noise floor for the same carrier is less than <inline-formula> <tex-math>$1.3 times 10^{-16}$ </tex-math></inline-formula> at 1 second averaging time (<inline-formula> <tex-math>$tau $ </tex-math></inline-formula>) with a 0.5 Hz bandwidth. Further improvement can be achieved with the use of cross-correlation techniques. To our knowledge, this represents the lowest flicker noise and Allan deviation performance ever reported for a digital measurement system.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"6 ","pages":"44-52"},"PeriodicalIF":2.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11424558","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147557995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Validation of mSOUND Using Fully Heterogeneous Skull Models","authors":"Jeffrey Bell;Lu Xu;Hong Chen;Yun Jing","doi":"10.1109/OJUFFC.2026.3677158","DOIUrl":"https://doi.org/10.1109/OJUFFC.2026.3677158","url":null,"abstract":"In this work, we present a wave solver incorporated into mSOUND, an open-source MATLAB toolbox for acoustic simulations. The solver achieves an accuracy-computational efficiency balance for acoustic simulations through strongly heterogeneous media. We demonstrate its usefulness in simulating transcranial focused ultrasound through fully heterogeneous skull models, in which each voxel is assigned a unique speed of sound, density, and absorption coefficient. We compare the solver’s computation times and accuracy against the widely-used full-wave solver k-Wave, achieving computational savings by two orders of magnitude while maintaining comparable accuracy, particularly in the focal region. To obtain a fully heterogeneous skull model, conversions from Hounsfield unit (HU) maps obtained via computed tomography (CT) scans to acoustic variables are needed. These conversions require a maximum speed of sound parameter to be assigned as a known input. In this work, we also investigate the effect changing this parameter has on the acoustic field as well as mSOUND’s accuracy relative to k-Wave. Over four skull samples and three maximum speeds of sound, our results indicate a decrease in focal pressure and increase in error for mSOUND in the focal region as the maximum speed of sound increases.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"6 ","pages":"80-89"},"PeriodicalIF":2.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11455209","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147606337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reducing PM-to-AM Noise Conversion in Atomic Vapors","authors":"Kaitlin Harpenau;Nate Ristoff;James Camparo","doi":"10.1109/OJUFFC.2026.3691291","DOIUrl":"https://doi.org/10.1109/OJUFFC.2026.3691291","url":null,"abstract":"Laser phase noise (PM) to transmitted intensity noise (AM) conversion is a fundamental aspect of the field/matter interaction, and a major noise process that limits the frequency stability of next-generation atomic clocks. It arises from the absorption cross section’s dependence on laser phase and is especially pernicious for vertical-cavity surface-emitting lasers (VCSELs) given their relatively broad singlemode linewidths (e.g., 40 MHz). This is unfortunate, since VCSELs (with their very low operating power and low probability for mode hops) are otherwise ideal for quantum devices. Here, we demonstrate that atomic spectroscopy with N VCSELs reduces the total PM-to-AM noise by a factor of ~<inline-formula> <tex-math>${mathrm {N}}^{mathrm {1/2}}$ </tex-math></inline-formula>. Consequently, atomic clocks with (for example) five VCSELs would have a signal-to-noise ratio (SNR5) approximately 120% higher than the same device operating with one VCSEL (SNR1) at the same total power: <inline-formula> <tex-math>$mathrm{SNR}_5 / mathrm{SNR}_1 cong 2.2$ </tex-math></inline-formula>.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"6 ","pages":"188-196"},"PeriodicalIF":1.8,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11512016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148442375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Embedded-Compatible Low-Voltage Poling of PMUTs","authors":"Jan Helmerich;Manfred Wich;Benedikt George;Stefan J. Rupitsch","doi":"10.1109/OJUFFC.2026.3738034","DOIUrl":"https://doi.org/10.1109/OJUFFC.2026.3738034","url":null,"abstract":"Piezoelectric micromachined ultrasonic transducers (PMUTs) have the potential to be integrated into future applications of fingerprint sensors, ultrasonic communication, and implantable devices, where micrometer footprints are crucial and conventional bulk transducers’ dimensions are unsuitable. These PMUTs feature such millimeter to micrometer sizes, while their resonance frequencies still fall within the desired upper kHz to lower MHz range. Their working principle is based on the piezoelectric effect, while lead zirconate titanate (PZT) often serves as the material of choice. However, the piezoelectric response of the material strongly depends on its polarization state. This contribution investigates polarization techniques that can be applied within an embedded device and compares them with conventional DC poling at a higher electric field. The experiment comprised five PNZT (niobium-doped PZT) PMUTs fabricated in-house through sputtering instead of sol-gel deposition. Both the current and voltage profiles for each polarization procedure were recorded while laser Doppler vibrometer measurements captured the decrease in the PMUTs’ deflection over time. In addition, changes in resonance frequency and apparent power during PMUT excitation were monitored, while the quality factor <inline-formula> <tex-math>$Q$ </tex-math></inline-formula> was determined. The results indicate that the application of low-voltage poling can significantly enhance the PMUTs’ deflection by more than 125 %, while an internal bias field can influence the aging rate of the polarization state. In comparison, our conventional poling technique yielded a deflection increase of 928 %, and a decreased aging rate. Small changes in the apparent power and in the resonance frequency were partially observed during the depolarization process.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"6 ","pages":"293-306"},"PeriodicalIF":1.8,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11713488","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149188514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Machine Learning Approach for Telemetry-Based Frequency Stability Estimation of High Precision Clocks","authors":"James A. Mckelvy;Gregory Shin;Fiona Mcdaniel;H. Bryan Owings;Thejesh N. Bandi","doi":"10.1109/OJUFFC.2026.3685191","DOIUrl":"https://doi.org/10.1109/OJUFFC.2026.3685191","url":null,"abstract":"Frequency stability measurements require pairwise comparisons between comparably stable oscillators. It is not possible to assess the frequency stability of a lone oscillator in an isolated environment with classical phase techniques. To supplement the needs of frequency and timing practitioners in situations when phase comparisons are not available, we propose a novel technique for using an oscillator’s telemetry data and supervised learning to estimate its associated frequency stability. The effectiveness of the technique is demonstrated on a study involving six commercial active hydrogen masers (AHM). Two broad modeling variants are considered: an oscillator specific model (OSM), in which a supervised model is trained to estimate the dynamic frequency stability of a specific oscillator with historical data of that oscillator; and an oscillator agnostic model (OAM), in which a supervised model is trained to estimate the stability of an arbitrary oscillator using historical data from an assortment of comparable oscillators. The best performing OSM achieved a Mean Absolute Error (MAE) of 5.6e-16 on estimations of dynamic Allan deviation in a held-out test set, while the best performing OAM achieved an MAE of 6.5e-16. The results demonstrate the viability of the proposed method for performing frequency stability assessments in an isolated environment when pairwise comparisons are not possible.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"6 ","pages":"127-136"},"PeriodicalIF":2.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11483184","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147795988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Condition and Position Estimation Using Spatial Ultrasound and Machine Learning","authors":"M. Shahrul Amir Kamarulzaman;Shun Sato;Yuto Yasuda;Ryotaro Ohara;Shintaro Izumi;Hiroshi Kawaguchi","doi":"10.1109/OJUFFC.2026.3672406","DOIUrl":"https://doi.org/10.1109/OJUFFC.2026.3672406","url":null,"abstract":"This study addresses the significant risk of bathroom-related injuries, often exacerbated by slippery surfaces and delays in accident detection, particularly as individuals frequently bathe unattended. Traditional accident detection methods, including those based on radio waves, optical sensors, and cameras, have inherent limitations. Although previous research has explored beamforming with low-cost ultrasound array sensors for object detection, its considerable computational load necessitates alternative approaches, such as machine learning. This paper presents a novel position and condition estimation method employing a Transformer-based model coupled with ultrasound array sensors tailored for bathroom environments. The proposed model architecture incorporates an encoder and two distinct decoders to generate binary segmentation masks and depth estimations, complemented by a multilayer perceptron classification block for condition estimation. The model was trained on binary masks and depth images acquired from a depth camera. Input signals received at 227 kHz are processed through cross-correlation with 25 kHz transmitted signals, followed by downsampling. The performance evaluation was conducted in two areas: bathtub and general washroom. In the bathtub area, condition estimation achieved <inline-formula> <tex-math>$97.5~pm ~2.0$ </tex-math></inline-formula>% accuracy, whereas position estimation yielded a mean absolute error (MAE) of <inline-formula> <tex-math>$11.9~pm ~2.9$ </tex-math></inline-formula> cm and an intersection over union (IoU) of <inline-formula> <tex-math>$0.735~pm ~0.022$ </tex-math></inline-formula>. Similarly, for the washroom area, condition estimation accuracy was <inline-formula> <tex-math>$96.5~pm ~0.8$ </tex-math></inline-formula>%, with position estimation resulting in an MAE of <inline-formula> <tex-math>$14.1~pm ~2.0$ </tex-math></inline-formula> cm and an IoU of <inline-formula> <tex-math>$0.656~pm ~0.023$ </tex-math></inline-formula>. Notably, In the context of critical incident detection, the recall rates for drowning and falls were exceptionally high, exceeding <inline-formula> <tex-math>$99.3~pm ~1.5$ </tex-math></inline-formula> and <inline-formula> <tex-math>$99.5~pm ~1.0$ </tex-math></inline-formula>%, respectively. These results demonstrate the significant potential and effectiveness of the proposed method for robust accident detection within bathroom environments.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"6 ","pages":"53-63"},"PeriodicalIF":2.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11429595","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147557992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Toward Whole Hand and Wrist Kinematic Tracking With a Wearable A-Mode Ultrasound Probe","authors":"Giusy Spacone;Luca Benini;Andrea Cossettini","doi":"10.1109/OJUFFC.2026.3727192","DOIUrl":"https://doi.org/10.1109/OJUFFC.2026.3727192","url":null,"abstract":"A-mode ultrasound (US) has emerged as a promising modality for hand and wrist motion tracking. Prior works have mainly addressed static gesture classification or regression of a few degrees of freedom (DoFs), typically relying on non-wearable systems and external computing devices, and highlight the need for strategies to ensure robustness to sensor repositioning. In this work, we propose a framework for robust whole-hand and wrist kinematic tracking via wearable A-mode US using the WULPUS platform, tackling the regression of 23 DoFs directly on the probe. First, we introduce a compact (11285 parameters) multi-output convolutional neural network combined with an incremental training strategy, which improves inter-session generalization and reduces mean absolute error by more than 17% compared to a non-incremental approach. Second, we demonstrate, for the first time, the feasibility of end-to-end hand and wrist kinematic tracking entirely on-device. We deploy the model on the WULPUS nRF52832 microcontroller, achieving 0.73 mJ per inference, 29.1 ms latency, and showing the feasibility of full operation (data acquisition, online inference, and BLE streaming of results) within 33 mW, enabling up to 36 hours of continuous use and an 88% reduction in wireless bandwidth compared to raw data transmission.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"6 ","pages":"232-235"},"PeriodicalIF":1.8,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11666997","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148928271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Closed-Form Expression for the Point Spread Function in Synthetic Transmit Aperture Ultrasound Imaging","authors":"Shivani Sharma;Na Zhao;Yuan Xu","doi":"10.1109/OJUFFC.2026.3710123","DOIUrl":"https://doi.org/10.1109/OJUFFC.2026.3710123","url":null,"abstract":"The Point Spread Function (PSF) is an essential tool for characterizing the resolution and response of an imaging system. This paper presents, for the first time, closed-form expressions for the PSF in Synthetic Transmit Aperture (STA) ultrasound imaging. The expressions were first derived under the assumption that the imaging depth is much larger than the aperture and PSF sizes, and were then improved for the large-aperture configuration. The proposed PSF formulas explicitly include the position of the point object and are therefore spatially varying. They can be applied to both off-axis locations and near-field regions. Field II simulations validated the PSF expressions. In addition to visual inspections, we used two quantitative metrics — the correlation coefficient and the central frequency of the PSF — to evaluate the agreement between the proposed method and Field II. We also studied the PSF behavior in a large-aperture configuration, where the small-aperture assumption used in the derivation no longer holds. We found that rescaling the spectrum improved the performance of the proposed method for the large-aperture case. The proposed method can be applied to various applications, such as ultrasound image deconvolution and quantitative ultrasound imaging.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"6 ","pages":"197-212"},"PeriodicalIF":1.8,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11595313","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148747175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of Training Data Composition on Deep Learning-Based Cardiac Motion Estimation","authors":"Andrea Pulido;Nitin Burman;Sandro Queirós;Jan D’Hooge","doi":"10.1109/OJUFFC.2025.3641005","DOIUrl":"https://doi.org/10.1109/OJUFFC.2025.3641005","url":null,"abstract":"Cardiac ultrasound deformation imaging is a non-invasive and widely used modality for assessing left ventricular function. However, due to the variable image quality observed in clinical routine, deformation estimation remains challenging. Recently, deep learning (DL) approaches have been proposed to estimate motion from ultrasound images. In this study, we investigated whether combining in vivo data with a synthetic dataset during training improves motion estimation accuracy while also benchmarking the DL-based estimates against a state-of-the-art traditional optical flow method. Results demonstrate that the deep learning-based method excels in tracking the dense motion fields on a frame-by-frame basis. However, when performing contour tracking, it results in lower end-systolic peak strain values compared to the traditional optical flow method.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"5 ","pages":"286-291"},"PeriodicalIF":2.9,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11278840","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145778363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Added Value of Cascaded Plane Wave Imaging for Autocorrelation- and Cross-Correlation-Based Velocity Vector Imaging","authors":"Joosje M. K. De Bakker;Ingvild K. Ekroll;Anne E. C. M. Saris;Jørgen Avdal","doi":"10.1109/OJUFFC.2025.3639374","DOIUrl":"https://doi.org/10.1109/OJUFFC.2025.3639374","url":null,"abstract":"Velocity vector imaging (VVI) can suffer from poor signal-to-noise (SNR) conditions, eventually restricting the estimation of velocities at low SNRs. Cascaded dual-polarity wave (CDW) imaging has been shown to enhance blood-SNR, thereby improving cross-correlation-based VVI. However, the CDW decoding process is sensitive to motion, where imperfect summation and cancellation of pulses can lead to reduced amplitude gain and ghost pulses outside the main pulse. Multi/dual-angle transmits, combined with either autocorrelation- or cross-correlation-based axial velocity estimation, are commonly used for VVI. Both techniques have intrinsic limitations, such as speckle decorrelation and aliasing, and strengths, where autocorrelation is known to be more resistant to noise and cross-correlation results in more accurate estimates in high SNR conditions. This study evaluates the benefits of CDW imaging for both autocorrelation- and cross-correlation-based VVI using the FLUST simulation toolbox and experiments, including parabolic and rotational flow scenarios. The results indicate that autocorrelation performs consistently across the entire SNR range, while cross-correlation is more accurate and precise in high SNR conditions. CDW improves estimation performance in low SNR conditions, particularly for estimation of low velocities, with a more substantial performance boost for cross-correlation compared to autocorrelation. In general, CDW imaging shows to be beneficial for VVI, independent of the used velocity estimator.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"5 ","pages":"281-285"},"PeriodicalIF":2.9,"publicationDate":"2025-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11272879","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145778475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}