Signal Processing Unit Research Articles

Hybrid TOF-PET/MRI local transceiver coil

In order to enhance diagnostic capabilities Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRI) devices are combined into a single hybrid device providing an access to both metabolic and morphological information during a single examination. Typically the PET detectors are placed inside the diagnostic volume of the MRI scanner, however being outside the commonly used local transmit-receiver (transceiver) coils such as head or chest coils. Coils are made of plastic parts and metal conductors on which annihilation gamma quanta may scatter before reaching the PET detectors scintillating material. This fact could cause the worsening of PET images spatial resolution and the field-of-view for the PET detectors. We propose a solution based on a novel PET tomograph concept comprising multiple detection modules, built from polymer scintillation strip ended with silicon photodetectors, arranged circumferentially inside the working volume of the MRI local transceiver coil. The adaptive of the polymer scintillators in both shape and size properties allows for a use of a standard MRI coils constructions to be combined with PET detection system without influence on the coil shape, geometry and material properties optimized so far. Current work is focused on a dedicated detection electronics development based on silicon photodetectors arrays and digital signal processing unit that will operate in high static magnetic field as well as radiofrequency waves environment of MRI scanner. The novel approach to the hybrid local coil construction would allow for using any existing MRI system extending its functionality by the PET imaging feature. Disclosure Authors disclose any relationship that may bias the presentation.

Ultrasonic tightening control of a screw joint: A comparison of the clamp force accuracy from different tightening methods

Clamp force and its accuracy are investigated using torque, angle, gradient, and clamp force/elongation control. Phosphated, lightly oiled M14 and M10 bolts are tightened. A PowerMACS 4000 system with a QST62-350CT nutrunner is used in the experimental setup. An ultrasonic signal processing unit using a piezoelectric sensor fitted to the socket is used for signal generation and processing when evaluating clamp force. The ultrasonic clamp force control is based on a novel method for assuring correct echo and high repeatability measurements in the tightening system. Torque and angle are extracted from the tool control system. During the experiments a load cell is used to measure the clamp force in the joint. Combined head and thread friction is calculated at final torque and clamp force. The results show that the lowest scatter (3 s) in clamp force, approximately 2.9% can be obtained using ultrasonic clamp force control and the highest, approximately 18% when using torque control. The results are also compared to tightening factors described in VDI2230.

Development and Performance of a Hand-Held CZT Detector for In-Situ Measurements at the Emergency Response

Background: A hand-held detector for an emergency response was developed for nuclide identification and to estimate the information of the ambient dose rate in the scene of an accident as well as the radioactivity of the contaminants. Materials and Methods: To achieve this, the most suitable sensor was first selected as a cadmium zinc telluride (CZT) semiconductor and the signal processing unit from a sensor and the signal discrimination and storage unit were successfully manufactured on a printed circuit board. Results and Discussion: The performance of the developed signal processing unit was then evaluated to have an energy resolution of about 14 keV at 662 keV. The system control unit was also designed to operate the CZT detector, monitor the detector, battery, and interface status, and check and transmit the measured results of the ambient dose rate and radioactivity. In addition, a collimator, which can control the inner radius, and the airborne dust sampler, which consists of an air filter and charcoal filter, were developed and mounted to the developed CZT detector for the quick and efficient response of a nuclear accident. Conclusion: The hand-held CZT detector was developed to make the in-situ gamma-ray spectrometry and its performance was checked to have a good energy resolution. In addition, the collimator and the airborne dust sampler were developed and mounted to the developed CZT detector for a quick and efficient response to a nuclear accident.

Design of Cane Mechanism for Walking Aid of Visually Impaired Person

This paper presents a sensor-based cane mechanism for walking aid of the visually impaired person. We also describe an approach to decide properly the length of the specified cane mechanism. The cane mechanism has some sensors to identify the possibility of a collision between the cane user and an object and/or a person, and a signal processing unit that enables the user to recognize such a collision is attached in the mechanism. Thus, the walker using this cane can recognize in advance the possibility of such a collision in his walking process. Consequently, it is helpful for the visually impaired person to walk on a pedestrian road safely. The feature of the proposed cane mechanism and its availability have been shown through experimental works in a typical walking environment.

Shear wave transmissivity measurement by color Doppler shear wave imaging

Shear wave elastography is a useful method for evaluating tissue stiffness. We have proposed a novel shear wave imaging method (color Doppler shear wave imaging: CD SWI), which utilizes a signal processing unit in ultrasound color flow imaging in order to detect the shear wave wavefront in real time. Shear wave velocity is adopted to characterize tissue stiffness; however, it is difficult to measure tissue stiffness with high spatial resolution because of the artifact produced by shear wave diffraction. Spatial average processing in the image reconstruction method also degrades the spatial resolution. In this paper, we propose a novel measurement method for the shear wave transmissivity of a tissue boundary. Shear wave wavefront maps are acquired by changing the displacement amplitude of the shear wave and the transmissivity of the shear wave, which gives the difference in shear wave velocity between two mediums separated by the boundary, is measured from the ratio of two threshold voltages required to form the shear wave wavefronts in the two mediums. From this method, a high-resolution shear wave amplitude imaging method that reconstructs a tissue boundary is proposed.

Anti-Ambipolar Field-Effect Transistors Based On Few-Layer 2D Transition Metal Dichalcogenides.

Two-dimensional (2D) materials and their related van der Waals heterostructures have attracted considerable interest for their fascinating new properties. There are still many challenges in realizing the potential of 2D semiconductors in practical (opto)electronics such as signal transmission and logic circuit, etc. Herein, we report the gate-tunable anti-ambipolar devices on the basis of few-layer transition metal dichalcogenides (TMDs) heterostructures to gain higher information storage density. Our study shows that carrier concentration regulated by the gate voltage plays a major role in the "anti-ambipolar" behavior, where the drain-source current can only pass through in specific range of gate voltage (Vg) and it will be restrained if the Vg goes beyond the range. Several improved strategies were theoretically discussed and experimentally adopted to obtain higher current on/off ratio for the anti-ambipolar devices, such as choosing suitable p-/n-pair, increasing carrier concentration by using thicker-layer TMDs, and so on. The modified SnS2/WSe2 device with the current on/off ratio exceeding 200 and on-state Vg ranging from -20 to 0 V was successfully achieved. On the basis of the anti-ambipolar field-effect transistors (FETs), we also reveal the potential of three-channel device unit for signal processing and information storage. With the equal quantity N of device units, 3(N) digital signals can be obtained from such three-channel devices, which are much larger than 2(N) ones obtained from traditional two-channel complementary metal oxide semiconductors (CMOS).

Optimization of Matched and Mismatched Filters in Short Range Pulse Radars using Genetic Algorithm

Matched and mismatched filters are considered important parts of a radar signal processing unit. In this paper, we present an approach to optimize the matched filters and mismatched filters in short range pulse radars. For radar, the matched filter coefficients are the complex conjugates of transmitted code. We used binary phase codes as transmitted pulse. The disadvantage of binary phase codes is having high sidelobe levels in the output of correlation function. Thus, we decided to use optimization algorithms for finding binary phase codes with minimum peak sidelobe levels (MPS). After that, we succeeded in producing mismatched filter coefficients (Mis-co) for each code using floating point genetic algorithm (FGA) and we could generate and test the filter coefficients with maximum peak to sidelobe level ratio (PSR). For testing the filter, we plotted ambiguity function for each set of coefficients and tested the filter with Doppler shift.

Pulse-signal digitizer for high-temperature plasma diagnostic systems

A pulse-signal digitizer for laser, neutron, and gamma diagnostics of high-temperature plasma at the GOL-3 and GDL (Budker Institute of Nuclear Physics Siberian Branch, Russian Academy of Sciences) is described. The architecture of a two-channel 12-bit ADC12500PXIe digitizer with a sampling rate of 500MHz, a PXI Express interface, and a built-in reconfigurable digital signal processing unit is described. The results of ADC12500PXIe metrological tests are presented: its signal-to-noise ratio (SNR), jitter, effective number of bits, and differential and integral nonlinearities are shown. The high-temperature plasma diagnostic systems based on ADC12500PXIe are considered. The structure of the digital signal processing unit that was modified for a prototype of the ITER vertical neutron camera (Cadarache, France) is described.

3D Body Scanning Measurement System Associated with RF Imaging, Zero-padding and Parallel Processing

Abstract This work presents a novel signal processing method for high-speed 3D body measurements using millimeter waves with a general processing unit (GPU) and zero-padding fast Fourier transform (ZPFFT). The proposed measurement system consists of a radio-frequency (RF) antenna array for a penetrable measurement, a high-speed analog-to-digital converter (ADC) for significant data acquisition, and a general processing unit for fast signal processing. The RF waves of the transmitter and the receiver are converted to real and imaginary signals that are sampled by a high-speed ADC and synchronized with the kinematic positions of the scanner. Because the distance between the surface and the antenna is related to the peak frequency of the conjugate signals, a fast Fourier transform (FFT) is applied to the signal processing after the sampling. The sampling time is finite owing to a short scanning time, and the physical resolution needs to be increased; further, zero-padding is applied to interpolate the spectra of the sampled signals to consider a 1/m floating point frequency. The GPU and parallel algorithm are applied to accelerate the speed of the ZPFFT because of the large number of additional mathematical operations of the ZPFFT. 3D body images are finally obtained by spectrograms that are the arrangement of the ZPFFT in a 3D space.

Hybrid electro-optic plasmonic modulators based on directional coupler switches

By breaking the diffraction limit, plasmonics enable the miniaturization of integrated optical signal processing units in a platform compatible with traditional CMOS technology. In such architectures, modulators and switches are essential elements for fast and low-power optical signal processing. This work presents the design of a CMOS-compatible hybrid plasmonic modulator based on directional couplers enhanced with a layer of electro-optic polymer. The modulator shows very broad operating window with low crosstalk values and very small footprint with respect to similar couplers and switches of the silicon photonics platform.

A Fully Integrated IEEE 802.15.7 Visible Light Communication Transmitter With On-Chip 8-W 85% Efficiency Boost LED Driver

This paper presents an IEEE 802.15.7 Physical Layer I (PHY-I) standard compliant visible light communication (VLC) transmitter system-on-a-chip (SoC), enabling the use of ordinary white LED lights as beacons or broadcasters for location-based applications. The mixed-signal SoC integrates a baseband digital signal processing (DSP) unit, a VLC modulator, and a switching boost LED driver with an on-chip power MOSFET. The DSP unit supports various coding schemes as well as both the on-off keying (OOK) modulation and the variable pulse-position modulation specified in the aforementioned standard. The boost LED driver is designed to power a matrix of 4 × 5 LEDs using Li-ion batteries for portable applications. The SoC simultaneously supports VLC and LED illumination with nine dimming levels. Implemented in a 0.35-μm CMOS process with 20-V devices, the SoC achieves a measured VLC data rate of up to 266 kb/s at a package error rate (PER) < 10% using a 211 −1 PRBS (pseudo random binary sequence) input. The communication distance measured is more than 2 m using no optical lens with the link efficiency of 5 nJ/bit. From an input at 3–5 V, the boost converter generates an output at 6–20 V with a 92% peak efficiency and an 8-W rating.

Development of an 8K full-resolution single-chip color image acquisition system

We have been researching compact 8K ultra-high definition television (UHDTV) camera systems for practical use. In this paper, we describe the world's first 8K &#x201C;full-resolution&#x201D; single-chip image acquisition system. This system can obtain an 8K full-resolution image at 60 frames-per-second, which has 33 megapixels for each color, using a 133-megapixel color CMOS image sensor. To reduce the size of the camera head, the signal processing is implemented in the separated camera control unit (CCU). The signal from the camera head to the CCU is transmitted using four 25-Gbps optical signals through one single-mode optical fiber by wavelength division multiplexing (WDM) technology. The signal processing unit can process all the 133-megapixel image data in real-time and can output an 8K video signal that is compliant with the ARIB STD-B58 and ITU-R BT. 2077 standards (U-SDI).

Microseismic Real-time Monitoring System Based on Virtual Instruments

Geological disasters such as rock burst coal and gas outburst in coal mines have inevitable link with micro-seismic phenomenon intrinsically. Monitoring the underground microseismic signals could determine the scope and extent of the underground rock and provide strong evidence for underground mine safety monitoring. A microseismic real-time monitoring system design based on virtual instrument was presented, using thirty two channels front microseismic signal processing unit, data acquisition card DAQ-6343, realizing multi-channel analog microseismic signals acquisition, achieved a real-time monitoring and analysis of microseismic signals combined with the microseismic method and improved adaptive wavelet transform processing algorithms in the LabVIEW platform. System monitoring results agree well with the actual mine earthquake, the error of obtained positioning results is small, realizing a real-time microseismic monitoring and analysis.

Integrated real time bowel sound detector for artificial pancreas systems

This paper reports an ultra-low power real time bowel sound detector with integrated feature extractor for physiologic measure of meal instances in artificial pancreas devices. The system can aid in improving long term diabetic patient care and consists of a front end detector and signal processing unit. The front end detector transduces the initial bowel sound recorded from a piezoelectric sensor into a voltage signal. The signal processor uses a feature extractor to determine whether a bowel sound is detected. The feature extractor consists of a low noise, low power signal front-end, peak and trough locator, signal slope and width detector, digitizer, and bowel pulse locator. The system was fabricated in a standard 0.18μm CMOS process, and the bowel sound detection system was characterized and verified with experimentally recorded bowel sounds. The integrated instrument consumes 53μW of power from a 1V supply in a 0.96mm2 area, and is suitable for integration with portable devices.

Multiplier Design Utilizing Tri Valued Logic for RLNS Based DSP Applications

Residue Number System (RNS) has proved shaping the Digital Signal Processing (DSP) units into highly parallel, faster and secured entities. The computational complexity of the multiplication process for a RNS based design can be reduced by indulging Logarithmic Number System (LNS). The combination of these unusual number systems forms Residue Logarithmic Number System (RLNS) that provides simple internal architectures. Till date RLNS based processing units are designed for binary logic based circuits. In order to reduce the number of input output signals in a system, the concept of Multiple Valued Logic (MVL) is introduced in literature. In that course of research, this paper uses Tri Valued Logic (TVL) in RLNS technique proposed, to further reduce the chip area and delay value. Thus in this research work three different concepts are proposed, it includes the design of multiplier for RLNS based application for number of bits 8, 16 and 32. Next is the utilization of TVL in the proposed multiplication structure for RLNS based system along with the error correction circuits for the ternary logarithmic and antilogarithmic conversion process. Finally the comparison of the two multiplication schemes with the existing research of multiplier design for RNS based system using booth encoding concepts. It can be found that the proposed technique using TVL saves on an average of about 63% of area occupied and 97% of delay value respectively than the existing technique.

Basic parameters of front-end microelectronic units of detector electronics

Results of the analysis of literature sources on development of microelectronic signal acquisition and processing units for ionizing radiation detectors in large-scale physical experiments are given. The basic parameters of these units, such as the channel number, power consumption per channel, conversion coefficient and noise level are summarized in the generalizing table. Conclusions on the performed analysis are made and trends in the design and implementation of the considered units manufactured as applications specific integrated circuits are noted.

Millimeter Wave Power Monitoring in EAST ECRH System

This paper presents a stable millimeter-wave power monitoring system for ECRH on EAST tokamak. The real-time power monitoring was realized based on power monitor miter bends. The “Exchange” method was proposed to monitor the reflection power for RF protection. A cRIO-based signal process unit was designed, it is robust and has the response time of $1~\mu \text{s}$ . The power monitoring system was tested and the experimental results were discussed.

Methods to Improve the Efficiency of Recognition of Speech Signals in Voice Control Systems

An improved speech recognition algorithm has been developed with additional signal processing units to increase the number of comparative data parameters and to reduce the natural and spectral distortion of speech signals. Using a verified database an experimental study of the algorithm was conducted.

Fiber Bragg grating sensing system using a TO-can–based compact optical module for wavelength demodulation

A combined scheme using the light source of a reflective semiconductor optical amplifier (RSOA) and an optical signal processing unit (OSPU) based on the compact TO-can package is fabricated and characterized for a fiber Bragg grating (FBG) sensing system. Due to the optical feedback behavior from the FBG sensor, the RSOA is self-injection locked and lasing occurs at the Bragg wavelength. Using the wavelength-dependent filter method, all of the components in the OSPU are compactly integrated on the TO-can package with a height of 17.6 mm and diameter of 6.0 mm. The wavelength demodulating output signals are based on the optical power difference, depending only on the wavelengths without the effect of input optical power variations. The sensitivity of the output signal to temperature shows 0.026 dB/°C . The entire FBG sensing system has an excellent linear response to temperatures controlled with an accuracy of ±0.3°C .

An Integrated System for Superharmonic Contrast-Enhanced Ultrasound Imaging: Design and Intravascular Phantom Imaging Study

Superharmonic contrast-enhanced ultrasound imaging, also called acoustic angiography, has previously been used for the imaging of microvasculature. This approach excites microbubble contrast agents near their resonance frequency and receives echoes at nonoverlapping superharmonic bandwidths. No integrated system currently exists could fully support this application. To fulfill this need, an integrated dual-channel transmit/receive system for superharmonic imaging was designed, built, and characterized experimentally. The system was uniquely designed for superharmonic imaging and high-resolution B-mode imaging. A complete ultrasound system including a pulse generator, a data acquisition unit, and a signal processing unit were integrated into a single package. The system was controlled by a field-programmable gate array, on which multiple user-defined modes were implemented. A 6-, 35-MHz dual-frequency dual-element intravascular ultrasound transducer was designed and used for imaging. The system successfully obtained high-resolution B-mode images of coronary artery ex vivo with 45-dB dynamic range. The system was capable of acquiring in vitro superharmonic images of a vasa vasorum mimicking phantom with 30-dB contrast. It could detect a contrast agent filled tissue mimicking tube of 200μm diameter. For the first time, high-resolution B-mode images and superharmonic images were obtained in an intravascular phantom, made possible by the dedicated integrated system proposed. The system greatly reduced the cost and complexity of the superharmonic imaging intended for preclinical study. Significant: The system showed promise for high-contrast intravascular microvascular imaging, which may have significant importance in assessment of the vasa vasorum associated with atherosclerotic plaques.