High-speed USB Interface Research Articles

Testing and application of an integrated fluxgate sensor DRV425

Abstract The article presents testing of a miniature fluxgate sensor developed and manufactured by Texas Instruments as well as an application of the sensor in a compact magnetic field probe with USB interface and LabView based software. Several basic properties of the sensor were evaluated and compared with the datasheet specifications. Offset stability measurements have indicated some possible problems for applications that require very high DC and low-frequency precision. Jumps in offset were present for some of the devices, frequency and duty of the jumps varying between individual pieces and with respect to the supply voltage. Magnetic probe for fast and handy measurements of DC and AC (up to 30 kHz) magnetic fields (up to ±1 mT) is also presented. The probe contains 24-bit analog to digital converter, microcontroller and high-speed USB interface which allows a live view of the signal in time and spectral charts. The probe proved to be very useful for the DRV425 debugging, application development, EMC measurements and magnetic field demonstrations activities.

A Light-Weight Rapid Control Prototyping System Based on Open Source Hardware

In this paper, we propose a light-weight rapid control prototyping (RCP) system based on off-the-shelf open source hardware to achieve high performance computing, cost effectiveness, portability, and easy accessiblity. The proposed RCP system consists of a PC-based computer-aided control system design (CACSD) tool for computing control action and tiny palm-sized open source hardware for input and output (I/O) operation and data transfer through a built-in high-speed USB interface. The popular-priced and portable open source hardware is used as a bridge between CACSD tools and real plants to deliver the control and sensor data at the sampling time points. Ten I/O function blocks written in C code are developed based on the CACSD tool employed for the proposed light-weight RCP system in order to handle I/O operation in a simple way. In addition, we suggest two practical strategies, a batch transfer strategy and a variable sampling period method, to increase the sampling rate of the control system. It is shown through experiment that the proposed light-weight RCP system works well up to a sampling rate of 2 kHz without adopting expensive hardware and C code generators. It is expected that the proposed RCP system will be considered as affordable and readily available to schools for mass education.

Design of a Wireless Laser Pointer Based on MCU

Wireless laser pointer is widely used in multimedia teaching. Due to the usage of professional high speed USB interface chips and USB2.0 protocol, the price of a wireless laser pointer in the market with the only function of changing PPT pages is about 50 dollar.This paper completes a very low price design of wireless laser pointer for multimedia teaching use based on STC89C52RC MCU and nRF905 single-chip radio transceivers,which can complete not only PPT page turning forward or backward but also black screen, drawing lines with fluorescent pen or needlepoint.

COLOR SPECTROGRAPHIC PHONOCARDIOGRAPHY FOR THE DETECTION AND CHARACTERIZATION OF PEDIATRIC HEART MURMURS: A CASE SERIES

Although auscultation of the heart remains central in the detection of abnormal heart sounds and murmurs that are frequently indicative of serious cardiac pathology, the application of electronic methods to this end remains rarely used in daily clinical practice. In this report we provide a series of examples showing how the phonocardiogram can be analyzed quantitatively using color spectrographic techniques and discuss how such methods may be of future value for noninvasive cardiac monitoring. Using a sound recording system, we recorded the heart sounds and data acquisition using the program Gold Wave ( http://www.goldwave.com ) to collect data from a high-speed USB interface. Sample color spectrogram analysis of the obtained signals was performed using custom software written in MATLAB. Data was collected from a number of infants and adults with cardiac structural disease as well as from some normal individuals. Our data is presented as a series of 13 cases. We expect the application of spectrographic techniques to phonocardiography to grow substantially as ongoing research and clinical experience demonstrates its utility in various settings. Our evaluation of a simple, low-cost phonocardiographic recording and analysis system to assist in determining the characteristic features of heart murmurs shows promise in helping distinguish normal heart sounds, innocent systolic murmurs and pathological murmurs in children. It expected to be useful in other clinical settings as well.

Digital Subtraction Phonocardiography (DSP) applied to the detection and characterization of heart murmurs

BackgroundDuring the cardiac cycle, the heart normally produces repeatable physiological sounds. However, under pathologic conditions, such as with heart valve stenosis or a ventricular septal defect, blood flow turbulence leads to the production of additional sounds, called murmurs. Murmurs are random in nature, while the underlying heart sounds are not (being deterministic).InnovationWe show that a new analytical technique, which we call Digital Subtraction Phonocardiography (DSP), can be used to separate the random murmur component of the phonocardiogram from the underlying deterministic heart sounds.MethodsWe digitally recorded the phonocardiogram from the anterior chest wall in 60 infants and adults using a high-speed USB interface and the program Gold Wave http://www.goldwave.com. The recordings included individuals with cardiac structural disease as well as recordings from normal individuals and from individuals with innocent heart murmurs. Digital Subtraction Analysis of the signal was performed using a custom computer program called Murmurgram. In essence, this program subtracts the recorded sound from two adjacent cardiac cycles to produce a difference signal, herein called a "murmurgram". Other software used included Spectrogram (Version 16), GoldWave (Version 5.55) as well as custom MATLAB code.ResultsOur preliminary data is presented as a series of eight cases. These cases show how advanced signal processing techniques can be used to separate heart sounds from murmurs. Note that these results are preliminary in that normal ranges for obtained test results have not yet been established.ConclusionsCardiac murmurs can be separated from underlying deterministic heart sounds using DSP. DSP has the potential to become a reliable and economical new diagnostic approach to screening for structural heart disease. However, DSP must be further evaluated in a large series of patients with well-characterized pathology to determine its clinical potential.

A color spectrographic phonocardiography (CSP) applied to the detection and characterization of heart murmurs: preliminary results

BackgroundAlthough cardiac auscultation remains important to detect abnormal sounds and murmurs indicative of cardiac pathology, the application of electronic methods remains seldom used in everyday clinical practice. In this report we provide preliminary data showing how the phonocardiogram can be analyzed using color spectrographic techniques and discuss how such information may be of future value for noninvasive cardiac monitoring.MethodsWe digitally recorded the phonocardiogram using a high-speed USB interface and the program Gold Wave http://www.goldwave.com in 55 infants and adults with cardiac structural disease as well as from normal individuals and individuals with innocent murmurs. Color spectrographic analysis of the signal was performed using Spectrogram (Version 16) as a well as custom MATLAB code.ResultsOur preliminary data is presented as a series of seven cases.ConclusionsWe expect the application of spectrographic techniques to phonocardiography to grow substantially as ongoing research demonstrates its utility in various clinical settings. Our evaluation of a simple, low-cost phonocardiographic recording and analysis system to assist in determining the characteristic features of heart murmurs shows promise in helping distinguish innocent systolic murmurs from pathological murmurs in children and is expected to useful in other clinical settings as well.

A high-performance digital system for electrical capacitance tomography

This paper describes a recently developed digital-based data acquisition system for electrical capacitance tomography (ECT). The system consists of high-capacity field-programmable gate arrays (FPGA) and fast data conversion circuits together with a specific signal processing method. In this system, digital phase-sensitive demodulation is implemented. A specific data acquisition scheme is employed to deal with residual charges in each measurement, resulting in a high signal-to-noise ratio (SNR) at high excitation frequency. A high-speed USB interface is employed between the FPGA and a host PC. Software in Visual C++ has been developed to accomplish operational functions. Various tests were performed to evaluate the system, e.g. frame rate, SNR, noise level, linearity, and static and dynamic imaging. The SNR is 60.3 dB at 1542 frames s−1 for a 12-electrode sensor. The mean absolute error between the measured capacitance and the linear fit value is 1.6 fF. The standard deviation of the measurements is in the order of 0.1 fF. The dynamic imaging test demonstrates the advantages of high temporal resolution of the system. The experimental results indicate that the digital signal processing devices can be used to construct a high-performance ECT system.

Imaging photomultiplier array with integrated amplifiers and high-speed USB interface

Multianode photomultiplier tube (PMT) arrays are finding application as convenient high-speed light sensitive devices for plasma imaging. This paper describes the development of a USB-based "plug-n-play" 16-channel PMT camera with 16 bits simultaneous acquisition of 16 signal channels at rates up to 2 MSs per channel. The preamplifiers and digital hardware are packaged in a compact housing which incorporates magnetic shielding, on-board generation of the high-voltage PMT bias, an optical filter mount and slits, and F-mount lens adaptor. Triggering, timing, and acquisition are handled by four field-programmable gate arrays (FPGAs) under instruction from a master FPGA controlled by a computer with a LABVIEW interface. We present technical design details and specifications and illustrate performance with high-speed images obtained on the H-1 heliac at the ANU.

High frequency coded imaging system with RF

Coded transmission is an approach to solve the inherent compromise between penetration and resolution required in ultrasound imaging. Our goal was to examine the applicability of the coded excitation to HF (20-35 MHz) ultrasound imaging. A novel real-time imaging system for research and evaluation of the coded transmission was developed. The digital programmable coder- digitizer module based on the field programmable gate array (FPGA) chip supports arbitrary waveform coded transmission and RF echo sampling up to 200 megasamples per second, as well as real-time streaming of digitized RF data via a high-speed USB interface to the PC. All RF and image data processing were implemented in the software. A novel balanced software architecture supports real-time processing and display at rates up to 30 frames/sec. The system was used to acquire quantitative data for sine burst and 16-bit Golay code excitation at 20 MHz fundamental frequency. SNR gain close to 14 dB was obtained. The example of the skin scan clearly shows the extended penetration and improved contrast when a 35-MHz Golay code is used. The system presented is a practical and low-cost implementation of a coded excitation technique in HF ultrasound imaging that can be used as a research tool as well as to be introduced into production.

Digital High Frequency Coded Imaging System

Coded transmission is an approach to solve the inherent compromise between penetration and resolution required in ultrasound imaging. It is universally acknowledged that this technique gives major improvement in SNR. A novel high frequency (20-35 MHz) ultrasound real-time imaging system for research and evaluation was developed. The digital programmable coder-digitizer module based on the field programmable gate array (FPGA) supports arbitrary waveform coded transmission and RF echoes sampling up to 200 MSPS, as well as real-time streaming of digitized RF data via a high speed USB interface to the PC. All RF and image data processing were implemented in the software. A novel balanced software architecture using CPU and GPU processing supports real-time processing and display at rates up to 30 frames/sec. The system was used to acquire data for sine burst and 16-bit Golay code excitation using a single element scanning head with thick film focused spherical transducer 25 MHz center frequency and 56% system bandwidth. SNR gain for the Golay codes (referenced to single burst) of 15 dB for 20 MHz and 16 dB for 35 MHz were obtained. In water the axial resolution for both single burst and the Golay codes was the same FWMH=20 ns at 20 MHz and FWMH=15 ns at 35 MHz.