Pulse Width Of Signal Research Articles

Short Time Interval Measurement Method Based on Compensation

In this paper, we use a compensation method of the measured short interval to improve the measurement accuracy by two groups of multiplex. By using two groups of multi-channel monostable pulse signal as a compensation signal, we respectively compensate time difference between the starting/ending measured short time interval and the reference signal. Pulse width of each compensation signal is uniform increasing and incremental sum is a reference signal cycle. We select the average value of two compensation signals pulse width as the beginning and the end of the time difference when the reference signal value jumps after compensation. Then according to the number of reference signal and two compensation time difference we can obtain measured short time interval. Error analysis and evaluation of uncertainty measurement show that the precision of this method is decided by pulse width increment of adjacent compensation signals. The experimental data shows that the method effectively reduces the measurement error of one reference signal cycle in the measurement of time interval.

Acquisition System for the Arbitrary Pulse Width and Position Signals Application in Ultrasound

Acquisition System for the Arbitrary Pulse Width and Position Signals Application in Ultrasound

Pulse-width analysis for neutron capture cross-section measurement using an NaI(Tl) detector

A fast data acquisition method based on pulse-width analysis was developed for measuring neutron capture cross-sections using an NaI(Tl) detector. The new method was tested by detecting γ-rays from standard γ-ray sources and neutron-induced reactions. Non-linear relation between the γ-ray energy and the pulse width of the detector output signal was studied. The neutron beam experiments were performed using a pulsed neutron beam from a spallation neutron source at the Japan Proton Accelerator Research Complex. Detector-deposited energy spectra were reconstructed from the pulse-width spectra using the parameterized relation between the pulse width and the γ-ray energy. Time response properties of the pulse-width analysis method were compared with the traditional pulse-height analysis method. Detailed analysis of the experimental results demonstrated that the present method was more resistive to intense γ-ray bursts from the spallation neutron source.

Efficient time gating in ultrafast optical TDM networks

Ultrafast optical communication is the backbone of high-speed global networking infrastructure. Optical time division multiplexing (OTDM) is a popular technique for embedding data from many simultaneous users on a single optical channel. This paper studies the optimal clock signal used in optical time gating to extract the data of the desired user in an OTDM network. We show that the pulse width of the clock signal can be optimized to achieve a minimum bit error rate (BER) in these networks. In this paper, we assume that the optical clock signal used for time gating has jitter, and there is therefore a delay variation between the clock and data signals. We model this delay as a zero mean Gaussian random variable. Using this model, an analytical BER expression is derived for systems with Gaussian pulses. In the numerical results, we find the optimal values of the clock pulse width by evaluating the BER versus the pulse width for different variances of the delay. Simulation results are also presented to evaluate the accuracy of the analytical expression.

Improved inverter‐based read‐out scheme for low‐power ISFET sensing array

The digital read-out scheme in an ion-sensitive field effect transistor (ISFET) sensing array is more advantageous when compared with the analogue counterpart because of its lower power consumption, smaller area and less susceptibility to environmental noise and parasitics. An improved read-out scheme is proposed in which each ISFET is stacked with a CMOS inverter to form a pH-to-time converter. The pH level of the solution regulates the strength of the ISFET, which in turn modulates the delay of the stacked inverter and hence the pulse width of the output signal. Simulation results using the 0.18 µm/2.5 V CMOS process show that the modulated pulse width changes linearly over a wide range of pH. The design achieves five orders of magnitude smaller leakage and 40% lower dynamic power consumption, while it requires only 50% of silicon area when compared with the conventional design. It is therefore more suitable for large ISFET arrays implemented in nano-scale CMOS technologies.

4-Gb/s Parallel Receivers With Adaptive FEXT Cancellation by Pulse Width and Amplitude Calibrations

Two 4-Gb/s parallel receivers with adaptive far-end crosstalk (FEXT) cancellation are presented, which requires a calibration mode. A digitally controlled high-pass filter and a variable-gain amplifier are used to generate the crosstalk cancellation (XTC) signal. The pulse width and amplitude of the XTC signal are automatically calibrated to match the FEXT signal for different channel spacing. It is expected to minimize the residual FEXT signal. Two receivers using the proposed adaptive XTC are fabricated in 40-nm CMOS technology and the core area occupies 0.045 mm2. The power consumption from a 0.9-V supply is 19.8 mW. For two 4-Gb/s PRBS of 27 - 1 passing through FR4 PCB traces with 5-in long and 8-mil spacing, the measured peak-to-peak jitter of data is reduced by 27.78 ps by using the proposed adaptive XTC.

MEMS piezoelectric artificial basilar membrane with passive frequency selectivity for short pulse width signal modulation

We demonstrated a novel MEMS artificial basilar membrane composed of a piezoelectric beam array that mimics the passive frequency selectivity of the cochlea and exhibits acoustic-to-electrical energy conversion. Each beam was designed to have a unique resonance frequency. To determine the resonance frequencies of the beams, the displacement and piezoelectric voltage were measured by applying a periodic chirped signal with a sound pressure level of 109.7dB. The measured resonance frequencies were in the range 10–37kHz. The piezoelectric signal was used to modulate a finite pulse-width signal for electrical stimulation; the pulse widths were in the range 0.43–5.1ms with sound pressure levels in the range 84.9–112.4dB.

DESIGN OF FUZZY LOGIC CONTROLLER FOR ONLINE SPEED REGULATION OF DC MOTOR USING PWM TECHNIQUE BASED ON LABORATORY VIRTUAL INSTRUMENT ENGINEERING WORKBENCH

This study details online speed regulation of DC motor using PWM technique based on LabVIEW. A fuzzy logic controller is designed to change the pulse width of switching signal applied to the converter and thereby the voltage fed to the armature of the separately excited DC motor to regulate the speed. The proposed system is connected to the server computer using a Data Acquisition Card (DAQ) and the server computer is configured to access remote client computer using Web publishing tool in LabVIEW. Now the speed of the DC motor can be controlled by a remote client computer with Internet connection. Laboratory Virtual Instrument Engineering Workbench (LabVIEW) is a graphical programming environment for creating custom applications that interact with real-world data or signals in fields such as science and engineering. The proposed online control system has been implemented to control the speeds of two different motors and the experimental results are plotted. The conventional controllers need design objectives such as steady state and transient characteristics of the closed loop system to be specified. But the designed fuzzy logic controller overcomes the problems with uncertainties in the plant parameters. The proposed online control technique saves time and reduces the manpower.

Effect of input signal and filter parameters on patterning effect in a semiconductor optical amplifier

A numerical investigation is presented to show the dependence of patterning effect (PE) of an amplified signal in a bulk semiconductor optical amplifier (SOA) and an optical bandpass filter based amplifier on various input signal and filter parameters considering both the cases of including and excluding intraband effects in the SOA model. The simulation shows that the variation of PE with input energy has a characteristic nature which is similar for both the cases. However the variation of PE with pulse width is quite different for the two cases, PE being independent of the pulse width when intraband effects are neglected in the model. We find a simple relationship between the PE and the signal pulse width. Using a simple treatment we study the effect of the amplified spontaneous emission (ASE) on PE and find that the ASE has almost no effect on the PE in the range of energy considered here. The optimum filter parameters are determined to obtain an acceptable extinction ratio greater than 10dB and a PE less than 1dB for the amplified signal over a wide range of input signal energy and bit-rate.

Research of all-optical ultra-wideband triplet signal source based on a single semiconductor optical amplifier

A novel scheme for all-optical ultra-wideband triplet signal pulse generation based on the cross-gain modulation (XGM) in a single semiconductor optical amplifier (SOA) is demonstrated. In this scheme, only one optical source and one SOA are needed, so the configuration is simple. Due to only one wavelength is included in the generated triplet pulse, no time difference between output signal light and probe light is introduced during the transmission process. By using the software of Optisystem 7.0, the impacts of the input signal width, the optical power and the wavelength of the optical source on the generated triplet pulse are numerically simulated and studied. The results show that the proposed scheme has better triplet signal pulse when the input signal pulse width is larger, and it is insensitive to the wavelength change within a certain range.

Characteristics of the photoacoustic signal excited by an intensity-modulated continuous-wave laser

The time-domain and frequency-spectrum characteristics of the photoacoustic signal excited by an intensity-modulated continuous-wave laser were obtained by calculation based on theoretical analysis, and were also compared with the characteristics of the sound signal excited by pulsed lasers. The frequency spectrum of the photoacoustic signal excited by an intensity-modulated continuous-wave laser was distributed evenly in a wider band width, and a higher signal to noise ratio (SNR) of the sound signal was achieved by a narrowband detector compared with the SNR of the sound signal excited by pulsed lasers. In order to improve the axial resolution of the photoacoustic signal excited by a continuous-wave laser, we increased the compression ratio and compressed the pulse width of the sound signal. Compared with the high pulse energy of the pulsed laser, the lower laser power of the continuous-wave laser can load a higher power density in biological tissues without damaging the tissues within a certain time.

Clinical Case Study Review

This manuscript describes a case in which, based on clinical observations, we hypothesize that a change in a cochlear implant recipient's electrode impedance and performance was attributed to a change in the recipient's physiology rather than a device failure. Of particular note was the finding that electrode impedances decreased after a period of nonuse of the implant as well as after steroid treatment. Retrospective single-subject case study review. Outpatient clinic. This paper describes outcomes for a 75-year-old male cochlear implant user. A change in electrode impedance and a decrease in speech recognition were addressed through cochlear implant programming, periods of nonuse of the implant, provision of steroids, and bilateral cochlear implantation. The primary measures of interest were serial assessment of electrode impedance and speech recognition. Secondary measures included assessment of implant stimulation levels and electrophysiologic responses. Electrode impedances decreased (improved) after a period of nonuse of the implant as well as after provision of steroid treatment. Recipient performance also improved but did not return to baseline levels. Atypical fluctuations in electrode impedance were observed with periods of CI use and nonuse. Additionally, after a 10-month period of constant fluctuation of electrode impedances with atypical morphology, electrode impedances stabilized to normal levels with a typical morphology within 3 days of steroid treatment. Given these observations, we hypothesized that the change in this recipient's electrode impedance as well as the decrease in this implant recipient's performance may be attributed to his physiology rather than to the device failure. Changes in electrode impedance accompanied by a decrease in this patient's performance were successfully addressed by a period of nonuse of the implant, provision of steroids, and an increase in the pulse width of the biphasic pulsatile signal used for stimulation. It should be noted that the results of this case are anecdotal in nature and may not apply to all cochlear implant recipients experiencing electrode impedance changes and/or deterioration in performance.

RF Pulse Signal Study in the SAW Delay-Line Sensor

The SAW delay-line sensor can obtain the energy of the RF pulse query signal through the wireless method. The RF pulse echo signal of the SAW delay-line sensor is significant effected by the different query pulse width of the RF pulse query signal, which is directly related to the sensor precision. The size of the IDT and reflectors, the distance between the IDT and reflector, and the distance among the different reflectors can affect the selection of the RF pulse query signal. The selection method of the query pulse width is discussed through the theoretical analysis and experimental analysis according to the SAW delay-line transmission characteristics. The query pulse width can be calculated directly through the design parameters of the SAW sensor.

Cross Time-Frequency Analysis for Combining Information of Several Sources: Application to Estimation of Spontaneous Respiratory Rate from Photoplethysmography

A methodology that combines information from several nonstationary biological signals is presented. This methodology is based on time-frequency coherence, that quantifies the similarity of two signals in the time-frequency domain. A cross time-frequency analysis method, based on quadratic time-frequency distribution, has been used for combining information of several nonstationary biomedical signals. In order to evaluate this methodology, the respiratory rate from the photoplethysmographic (PPG) signal is estimated. The respiration provokes simultaneous changes in the pulse interval, amplitude, and width of the PPG signal. This suggests that the combination of information from these sources will improve the accuracy of the estimation of the respiratory rate. Another target of this paper is to implement an algorithm which provides a robust estimation. Therefore, respiratory rate was estimated only in those intervals where the features extracted from the PPG signals are linearly coupled. In 38 spontaneous breathing subjects, among which 7 were characterized by a respiratory rate lower than 0.15 Hz, this methodology provided accurate estimates, with the median error {0.00; 0.98} mHz ({0.00; 0.31}%) and the interquartile range error {4.88; 6.59} mHz ({1.60; 1.92}%). The estimation error of the presented methodology was largely lower than the estimation error obtained without combining different PPG features related to respiration.

Vehicle power system condition prediction based on weighted hidden Markov model

A new condition prediction approach based on weighed Hidden Markov Model(HMM) was presented in order to solve the problem of trend prediction for vehicle power system.Through the establishment of the power system HMM,the hidden state of HMM was predicted by weighted prediction method,and the observed state of the model was calculated by the observation probability density of the maximum probability hidden state.The approach was applied to the state prediction of rate turn of the system voltage adjusting pulse width signals,and was compared to that of using BP(Back Propagation) neural network and Auto-Regression(AR) prediction model with the same sequence.The results show that the method has better prediction on the system state change.

Dynamic calibration method of high-pressure transducer based on quasi-δ function excitation source

This paper presents a dynamic calibration method of frequency response characteristics of high-pressure sensor. In this method, the pressure sensor was under high hydrostatic pressure in advance, then use the bullet impacted Hopkinson bar and generated quasi-δ function signal with small amplitude, which excited the sensor being calibrated. The excitation signal of sensor are collected, at the same time, output signal of the sensor are collected, and at last, the collected data are processed according to calibration principle and calculated the frequency response of the sensor being calibrated. This calibration method realized dynamic calibration of high pressure sensor under actual working pressure; it can realize the low limit frequency of the calibrated frequency range strictly reaches to zero frequency. This method can also be applied to acceleration sensor, transient high-temperature sensor, and other types of sensors. In this paper, the calibration principle of quasi-δ function dynamic calibration method is introduced. The relationship among pulse width of excitation signal, frequency range that can be calibrated and calibration precision is analyzed. The experimental results are also shown.

All-optical ultra-wideband doublet signal source based on the cross-gain modulation in a semiconductor optical amplifier

We propose a novel scheme to generate the ultra-wideband (UWB) doublet signal pulse based on the cross-gain modulation (XGM) in a semiconductor optical amplifier (SOA). In the scheme, only an optical source and an SOA are needed. As there is only one wavelength included in the output doublet signal pulse, no time difference between the upper and down pulses is introduced during the transmission process. By using the software of Optisystem 7.0, the impacts of the optical power, the SOA current, the wavelength and the input signal pulse width on the generated doublet pulse are simulated and tudied numerically. The results show that when the pulse width of the input signal pulse is larger, the output signal pulse is better, and is insensitive to the change of wavelength. In addition, the ultra-wideband positive and negative monocycles can be generated by choosing suitable optical source power and SOA current.

A downward signal processing method for rotary steerable drilling system based on signal similarity

Abstract To identify downhole command signals accurately and efficiently with negative fluid pulse intervals in the rotary steerable drilling engineering and solve the complex operation and high error rate problems in the command identification and explanation process of downhole receivers, this paper presents a signal process method based on signal similarity principle. In this method, command instructions expressed by drilling fluid pulse width signal are obtained by comparing the self-correlation degree of sampling signal amplitudes at each interval, and the downhole sampling signals are compared interval by interval according to a fixed rule, and command identification is achieved by three steps, i.e. judgment for the start of signal, calculation for digital bits of the command, and assembling of command word. The recursive practical algorithms suitable for downhole processing are proposed. The results show that the method can simplify operation program and improve the reliability and ability of interference killing for the signal identification, and is especially good for overcoming the effects of peak and periodic interference on time counting and the effects of inertia of transmitting channel and low frequency noise on signal jump edge judging.

Theory of Elimination of Emitted Optical Pulse/s Remotely

In this paper, the authors present a new theory that can be applied to remotely eliminate emitted optical pulse/s. The elimination of the optical pulses can be performed by increasing the threshold carrier density of the laser source during the time period of the injected pulse by exposing the laser diode to an incoherent external optical feedback (EOF) pulse at a specified value of external reflectivity. Consequently, the stimulated emission will not occur and approximately zero photon density will be achieved during the pulse width of the EOF signal. The proposed technique can be utilized to develop a new type of all-optical external encoder. In addition, it can be used to remotely control the laser source and, in turn, the whole optical communication system.

Vagus nerve stimulation: effectiveness and tolerability in 64 paediatric patients with refractory epilepsies

We discuss the effectiveness, tolerability, and safety of vagus nerve stimulation (VNS) as adjunctive therapy in 64 paediatric patients with refractory epilepsies. Sixty-four patients (34 male and 30 female) implanted with VNS for refractory epilepsy were analysed. Electroclinical features were compatible with Lennox-Gastaut syndrome in 46 patients, focal epilepsies in 10 patients, Dravet syndrome in three patients, epilepsy with myoclonic-astatic seizures in three patients, and West syndrome in two. The NeuroCybernetic Prosthesis (NCP) system (Cyberonics, Webster, TX, USA) was employed and the following stimulation parameters were used: output current of 1 to 2.5mA, signal frequency of 30Hz, signal pulse width of 500μs, and signal "on" and "off" times of 30 seconds and 5 minutes, respectively. Of 46 patients with LGS, 30 cases showed a significant improvement in seizure control, with a reduction in seizure frequency of at least 50%. Ten patients with focal epilepsy, three patients with myoclonic-astatic seizures, two patients with Dravet, and two patients with West showed a significant improvement in seizure control, with a reduction in seizure frequency of at least 50%. A good clinical response was evident early and efficacy progressively improved with the duration of treatment up to 36 months. In a significant number of patients, reduced seizure severity and shorter recovery time and hospital stay were also observed. VNS was well tolerated in all patients. VNS is an effective and well-tolerated treatment for paediatric patients with refractory epilepsies, improving quality of life and neuropsychological performance.