Time filter

Source Type

Du L.,Shenzhen Key Laboratory for Low Cost Healthcare | Yan Y.,Shenzhen Key Laboratory for Low Cost Healthcare | Wu W.,Shenzhen Key Laboratory for Low Cost Healthcare | Mei Q.,Guangdong University of Technology | And 3 more authors.
Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS | Year: 2013

Multiple-lead dynamic ECG recorders (Holter) play an important role in the earlier detection of various cardiovascular diseases. In this paper, we present the first several steps towards a 12-lead Holter system with high-performance AFE (Analogue Front-End) and enhanced digital processing. The system incorporates an analogue front-end chip (ADS1298 from TI), which has not yet been widely used in most commercial Holter products. A highly-efficient data management module was designated to handle the data exchange between the ADS1298 and the microprocessor (STM32L151 from ST electronics). Furthermore, the system employs a Field Programmable Gate Array (Spartan-3E from Xilinx) module, on which a dedicated real-time 227-step FIR filter was executed to improve the overall filtering performance, since the ADS1298 has no high-pass filtering capability and only allows limited low-pass filtering. The Spartan-3E FPGA is also capable of offering further on-board computational ability for a smarter Holter. The results indicate that all functional blocks work as intended. In the future, we will conduct clinical trials and compare our system with other state-of-the-arts. © 2013 IEEE.

Liu G.-Z.,Sun Yat Sen University | Wu D.,CAS Shenzhen Institutes of Advanced Technology | Mei Z.-Y.,CAS Shenzhen Institutes of Advanced Technology | Zhu Q.-S.,CAS Shenzhen Institutes of Advanced Technology | And 2 more authors.
Journal of Central South University | Year: 2013

Respiratory monitoring is increasingly used in clinical and healthcare practices to diagnose chronic cardio-pulmonary functional diseases during various routine activities. Wearable medical devices have realized the possibilities of ubiquitous respiratory monitoring, however, relatively little attention is paid to accuracy and reliability. In previous study, a wearable respiration biofeedback system was designed. In this work, three kinds of signals were mixed to extract respiratory rate, i.e., respiration inductive plethysmography (RIP), 3D-acceleration and ECG. In-situ experiments with twelve subjects indicate that the method significantly improves the accuracy and reliability over a dynamic range of respiration rate. It is possible to derive respiration rate from three signals within mean absolute percentage error 4.37% of a reference gold standard. Similarly studies derive respiratory rate from single-lead ECG within mean absolute percentage error 17% of a reference gold standard. © 2013 Central South University Press and Springer-Verlag Berlin Heidelberg.

Wen T.,CAS Shenzhen Institutes of Advanced Technology | Gu J.,CAS Shenzhen Institutes of Advanced Technology | Gu J.,Shenzhen Key Laboratory for Low Cost Healthcare | Li L.,CAS Shenzhen Institutes of Advanced Technology | And 5 more authors.
Ultrasonic Imaging | Year: 2016

Ultrasound is one of the most important medical imaging modalities for its real-time and portable imaging advantages. However, the contrast resolution and important details are degraded by the speckle in ultrasound images. Many speckle filtering methods have been developed, but they are suffered from several limitations, difficult to reach a balance between speckle reduction and edge preservation. In this paper, an adaptation of the nonlocal total variation (NLTV) filter is proposed for speckle reduction in ultrasound images. The speckle is modeled via a signaldependent noise distribution for the log-compressed ultrasound images. Instead of the Euclidian distance, the statistical Pearson distance is introduced in this study for the similarity calculation between image patches via the Bayesian framework. And the Split-Bregman fast algorithm is used to solve the adapted NLTV despeckling functional. Experimental results on synthetic and clinical ultrasound images and comparisons with some classical and recent algorithms are used to demonstrate its improvements in both speckle noise reduction and tissue boundary preservation for ultrasound images. © 2016 The Author(s).

Yu S.,CAS Shenzhen Institutes of Advanced Technology | Yu S.,Shenzhen Key Laboratory for Low Cost Healthcare | Zhang R.,CAS Shenzhen Institutes of Advanced Technology | Zhang R.,Shenzhen Key Laboratory for Low Cost Healthcare | And 5 more authors.
BioMedical Engineering Online | Year: 2013

Background: Fetal spinal magnetic resonance imaging (MRI) is a prenatal routine for proper assessment of fetus development, especially when suspected spinal malformations occur while ultrasound fails to provide details. Limited by hardware, fetal spine MR images suffer from its low resolution.High-resolution MR images can directly enhance readability and improve diagnosis accuracy. Image interpolation for higher resolution is required in clinical situations, while many methods fail to preserve edge structures. Edge carries heavy structural messages of objects in visual scenes for doctors to detect suspicions, classify malformations and make correct diagnosis. Effective interpolation with well-preserved edge structures is still challenging.Method: In this paper, we propose an edge-directed interpolation (EDI) method and apply it on a group of fetal spine MR images to evaluate its feasibility and performance. This method takes edge messages from Canny edge detector to guide further pixel modification. First, low-resolution (LR) images of fetal spine are interpolated into high-resolution (HR) images with targeted factor by bi-linear method. Then edge information from LR and HR images is put into a twofold strategy to sharpen or soften edge structures. Finally a HR image with well-preserved edge structures is generated. The HR images obtained from proposed method are validated and compared with that from other four EDI methods. Performances are evaluated from six metrics, and subjective analysis of visual quality is based on regions of interest (ROI).Results: All these five EDI methods are able to generate HR images with enriched details. From quantitative analysis of six metrics, the proposed method outperforms the other four from signal-to-noise ratio (SNR), peak signal-to-noise ratio (PSNR), structure similarity index (SSIM), feature similarity index (FSIM) and mutual information (MI) with seconds-level time consumptions (TC). Visual analysis of ROI shows that the proposed method maintains better consistency in edge structures with the original images.Conclusions: The proposed method classifies edge orientations into four categories and well preserves structures. It generates convincing HR images with fine details and is suitable in real-time situations. Iterative curvature-based interpolation (ICBI) method may result in crisper edges, while the other three methods are sensitive to noise and artifacts. © 2013 Yu et al.; licensee BioMed Central Ltd.

Nie Z.,CAS Shenzhen Institutes of Advanced Technology | Nie Z.,Shenzhen Key Laboratory for Low Cost Healthcare | Ma J.,Testing and Technology Center for Industrial Products | Li Z.,CAS Shenzhen Institutes of Advanced Technology | And 5 more authors.
Sensors (Switzerland) | Year: 2012

This paper presents the first characterization and modeling of dynamic propagation channels for human body communication (HBC). In-situ experiments were performed using customized transceivers in an anechoic chamber. Three HBC propagation channels, i.e., from right leg to left leg, from right hand to left hand and from right hand to left leg, were investigated under thirty-three motion scenarios. Snapshots of data (2,800,000) were acquired from five volunteers. Various path gains caused by different locations and movements were quantified and the statistical distributions were estimated. In general, for a given reference threshold è = -10 dB, the maximum average level crossing rate of the HBC was approximately 1.99 Hz, the maximum average fade time was 59.4 ms, and the percentage of bad channel duration time was less than 4.16%. The HBC exhibited a fade depth of -4 dB at 90% complementary cumulative probability. The statistical parameters were observed to be centered for each propagation channel. Subsequently a Fritchman model was implemented to estimate the burst characteristics of the on-body fading. It was concluded that the HBC is motion-insensitive, which is sufficient for reliable communication link during motions, and therefore it has great potential for body sensor/area networks. © 2012 by the authors; licensee MDPI, Basel, Switzerland.

Discover hidden collaborations