Showing papers on "Pulse-frequency modulation published in 2015"

Space-Vector Versus Nearest-Level Pulse Width Modulation for Multilevel Converters

Abstract: This paper studies the inherent relationship between two widely used pulse width modulation (PWM) methods for multilevel converters, i.e., the space vector modulation (SVM) method, also called space vector pulse width modulation, and the nearest-level modulation method. The nearest-level modulation method directly controls the voltage of each phase, while the SVM method simultaneously deals with all phases. It is demonstrated in this paper that the two modulation methods are functionally equivalent: with proper common-mode voltage injections, the nearest-level modulation method is equivalent to the SVM method; by selecting the appropriate redundant switching sequences and the corresponding duty cycles, the SVM method is equivalent to the nearest-level modulation method. Nevertheless, the SVM method can conveniently provide more flexibility of optimizing the switching patterns, without the need of designing sophisticated common-mode voltages. An efficient and flexible modulation method for any multiphase multilevel converter is, therefore, proposed, which combines the advantages of the nearest-level modulation and the SVM methods, i.e., both with less computational burden and high flexibility of optimizing the output waveforms. Simulation and experimental results validate the analysis.

A PWM and PFM Hybrid Modulated Three-Port Converter for a Standalone PV/Battery Power System

Abstract: A pulsewidth modulation (PWM) and pulse frequency modulation (PFM) hybrid modulated three-port converter (TPC) interfacing a photovoltaic (PV) source, a storage battery, and a load is proposed for a standalone PV/battery power system. The TPC is derived by integrating a two-phase interleaved boost circuit and a full-bridge $LLC$ resonant circuit. Hence, it features a reduced number of switches, lower cost, and single-stage power conversion between any two of the three ports. With the PWM and PFM hybrid modulation strategy, the dc voltage gain from the PV to the load is wide, the input current ripple is small, and flexible power management among three ports can be easily achieved. Moreover, all primary switches turn ON with zero-voltage switching (ZVS), while all secondary diodes operate with zero-current switching over full operating range, which is beneficial for reducing switching losses, switch voltage stress, and electromagnetic interference. The topology derivation and power transfer analysis are presented. Depending on the resonant states, two different operation modes are identified and explored. Then, main characteristics, including the gain, input current ripple, and ZVS, are analyzed and compared. Furthermore, guidelines for parameter design and optimization are given as well. Finally, a 500-W laboratory prototype is built and tested to verify the effectiveness and advantages of all proposals.

Variable-Frequency Phase Shift Modulation of a Dual Active Bridge Converter

Abstract: In this paper, a variable-frequency modulation method for a dual active bridge converter is introduced. The proposed method ensures zero-voltage switching over a wide power range with a minimal circulating current. Unlike previously presented modulation schemes, this modulation method can also be used for half-bridge variants of a traditional dual active bridge converter. The modulation method is given in a closed form, which makes it easy to apply in practice. Further, the phase drift phenomenon is discussed, and a simple phase drift compensation scheme is presented. Finally, a detailed analysis of the proposed modulation method is provided and its feasibility is verified by measurements.

New Three-Phase Symmetrical Multilevel Voltage Source Inverter

Abstract: This paper presents a new design and implementation of a three-phase multilevel inverter $(MLI)$ for distributed power generation system using low frequency modulation and sinusoidal pulse width modulation $(SPWM)$ as well. It is a modular type and it can be extended for extra number of output voltage levels by adding additional modular stages. The impact of the proposed topology is its proficiency to maximize the number of voltage levels using a reduced number of isolated dc voltage sources and electronic switches. Moreover, this paper proposes a significant factor $(F_{C/L})$ , which is developed to define the number of the required components per pole voltage level. A detailed comparison based on $F_{C/L}$ is provided in order to categorize the different topologies of the $MLI$ s addressed in the literature. In addition, a prototype has been developed and tested for various modulation indexes to verify the control technique and performance of the topology. Experimental results show a well-matching and good similarity with the simulation results.

A Novel Wall-Switched Step-Dimming Concept in LED Lighting Systems Using PFC Zeta Converter

Abstract: This paper presents the design, simulation, and implementation of a non-isolated discontinuous conduction mode operated Zeta-converter-based light-emitting diode (LED) driver with the novel wall-switched step-dimming concept to achieve power quality improvement at universal ac mains. The power-factor-corrected Zeta converter maintains constant output current to an LED load of 26 W and conserves the power quality requirements as per IEC 61000-3-2 for class C equipment with high efficiency. Moreover, to obtain cost benefit and size reduction, this converter utilizes reduced control circuitry for general-purpose LED lighting solutions. A cost-effective single-level dimming concept is implemented with current injection technique using a Zeta converter. A prototype is developed using AP1682, which utilizes pulse frequency modulation technique to regulate the output current for improving the input power factor and low total harmonic distortion (THD) of the input current. At full load and rated voltage of 220 V, the measured input power factor is 0.993 and current THD is 2.81% with an efficiency of 90.51%.

High-Speed Frequency Modulation of a 460-GHz Gyrotron for Enhancement of 700-MHz DNP-NMR Spectroscopy

Abstract: The high-speed frequency modulation of a 460-GHz Gyrotron FU CW GVI (the official name in Osaka University is Gyrotron FU CW GOI) was achieved by modulation of acceleration voltage of beam electrons. The modulation speed f m can be increased up to 10 kHz without decreasing the modulation amplitude δf of frequency. The amplitude δf was increased almost linearly with the modulation amplitude of acceleration voltage ΔV a. At the ΔV a = 1 kV, frequency spectrum width df was 50 MHz in the case of f m < 10 kHz. The frequency modulation was observed as both the variation of the IF frequency in the heterodyne detection system measured by a high-speed oscilloscope and the widths of frequency spectra df measured on a frequency spectrum analyzer. Both results well agree reasonably. When f m exceeds 10 kHz, the amplitude δf is decreased gradually with increasing f m because of the degradation of the used amplifier in response for high-speed modulation. The experiment was performed successfully for both a sinusoidal wave and triangle wave modulations. We can use the high-speed frequency modulation for increasing the enhancement factor of the dynamic nuclear polarization (DNP)-enhanced nuclear magnetic resonance (NMR) spectroscopy, which is one of effective and attractive methods for the high-frequency DNP-NMR spectroscopy, for example, at 700 MHz. Because the sensitivity of NMR is inversely proportional to the frequency, high-speed frequency modulation can compensate the decreasing the enhancement factor in the high-frequency DNP-NMR spectroscopy and keep the factor at high value. In addition, the high-speed frequency modulation is useful for frequency stabilization by a PID control of an acceleration voltage by feeding back of the fluctuation of frequency. The frequency stabilization in long time is also useful for application of a DNP-NMR spectroscopy to the analysis of complicated protein molecules.

Global synchronous pulse width modulation of distributed inverters

Abstract: Traditionally, the parallel-connected multi-leg inverter could assume the interleaved PWM to attenuate the switching frequency harmonics by using a single controller to generate the corresponding interleaved switching sequences. However, the interleaved PWM cannot be employed in multiple distributed inverters installed at different locations with their own controllers because the multiple independent controllers cannot work synchronously and the operational conditions are variable among the distributed inverters. The summed current harmonics of multiple distributed inverters could vary at the point of common coupling (PCC) and worsen the power quality of consumers. This paper therefore proposes a global synchronous pulse width modulation (GSPWM) method for the distributed inverters to attenuate the high frequency current harmonics at PCC meanwhile improve the PCC voltage quality. The optimal interleaved switching angles among the distributed inverters are calculated by fully considering the line impedances, the modulation indexes, the switching frequencies, the number of distributed systems and etc. Then the low frequency synchronous operation will synchronize the pulse width modulation sequences in the wanted variation range. Experimental results are presented to prove the validity of this method.

A novel modulation scheme and voltage balancing algorithm for modular multilevel converter

Abstract: This paper presents a low cost, less computational pulse width modulation scheme for a modular multilevel converter (MMC). In the present control approach, the reference output voltage is generated by averaging the two nearest voltage levels. The switching states corresponding to the two nearest voltage levels and their duty cycles are obtained from the instantaneous value of reference output voltage. The proposed modulation scheme is easily extended to any number of submodules per arm without any modifications. In addition, a voltage balancing algorithm is proposed for the balancing of submodule capacitors voltage. The performance of the proposed modulation scheme and voltage balancing algorithm is evaluated on the 2MVA/6kV MMC system with three-level flying capacitor submodules. Also, the proposed modulation scheme is compared with the conventional phase-shifted carrier pulse width modulation (PSC-PWM) scheme and the results are presented.

Analog Filtering Method for Sensorless AC Machine Control With Carrier-Frequency Signal Injection

Abstract: This paper analyzes the angle estimation errors for signal injection based sensorless control with an analog bandpass filter (BPF). The analog BPF has been used to reduce the level of the injection voltage. However, the frequency components of the current signal that have passed through the analog BPF have different phase delays. In addition, the injection voltage at the carrier frequency is distorted by the pulsewidth modulation. Because of these reasons, the angle estimation error includes the alternation at three or six times the rotating frequency and dc offset. The pattern of the angle estimation error depends on the quality factor of the analog BPF. In this paper, each cause of the angle estimation errors is studied and the experimental results verify these analyses. In addition, the filter design guide to reduce the angle estimation error is outlined.

Design and implementation of visible light communication system using pulse width modulation

Abstract: Visible Light Communication (VLC) is a relatively new technology which could potentially be complementary to the existing radio frequency communication system. VLC allows lamp or other kinds of light source not only used as illumination, but also as a data transmission at the same time. Single carrier modulation technique is suitable to be applied on VLC that does not require high-speed data transfer. In this paper, we proposed a visible light communication scheme using pulse width modulation (PWM) technique in transmitting data for running text application. To evaluate the PWM accuracy, experiments were conducted based on different parameters such as PWM frequency, transmitter-receiver distance, and the receiver's angle of view. Furthermore, we also measured the point-to-point communication system performance which resulted in 920 bps data transfer rate and 10−4 bit error rate (BER) without affecting the lighting function.

Analytical Evaluation of VCO-ADC Quantization Noise Spectrum Using Pulse Frequency Modulation

Abstract: Oversampled ADCs based on voltage-controlled oscillators have been analyzed using statistical models inherited from sigma-delta modulation. This letter shows that the discrete Fourier transform of a VCO-ADC output sequence can be calculated analytically for single tone inputs. The calculation is based on the transformation of the VCO output into a pulse frequency modulated signal that can be represented by a trigonometric series. Knowledge of the VCO-ADC output spectrum allows accurate evaluation of the SNDR dependence with the VCO oscillation frequency and gain constant. The SNDR predictions of the proposed model have been compared to behavioral simulations displaying only a deviation of 0.7 dB.

Power Control of Asymmetrical Frequency Modulation in a Full-Bridge Series Resonant Inverter

Abstract: The traditional power control schemes for induction heating device mainly focus on the pulse frequency modulation (PFM) and the pulse density modulation. But they cannot solve the problems of power control, efficiency, and load-adaption well. This paper presents and analyzes the asymmetrical frequency modulation (AFM) control scheme used in the full-bridge series resonant inverter. With the proposed AFM control technique, the output power is controlled by two variables: the operation frequency and the division factor. Better efficiency performance can be achieved in the medium and low output power range when compared with PFM. The principles as well as the zero-voltage switching condition of the AFM are explained and the power losses of switches are analyzed. A control algorithm that schedules the three control modes of AFM is experimentally verified with a digital signal processor based induction heating prototype. The load-adaption, noise and thermal distribution problem of switches are also analyzed.

A Study on Linear Frequency Modulation Signal Transmission by 4-D Antenna Arrays

Abstract: This paper presents a study on linear frequency modulation (LFM) pulsed signal transmission by four-dimensional (4-D) antenna arrays. LFM pulse is used as the input of 4-D antenna arrays and the influence brought by the periodic time modulation is analyzed. The relationship among pulse duration, chirp rate, sample frequency, time-modulation frequency, and propagation direction is analyzed and the restrictions to these parameters are highlighted. The transmitting and receiving structures are introduced and relevant signal processing steps are described. Numerical examples with several different time schemes, including the pulse shifting (PS) scheme and binary phase center motion (BPCM) scheme, are presented to demonstrate the effectiveness of the LFM signal transmission by 4-D arrays. Simulation results validate that original chirp signal can be correctly recovered and low sidelobe power patterns can be simultaneously achieved by 4-D antenna arrays, as long as the proposed limitations are satisfied.

12.5 An error-based controlled single-inductor 10-output DC-DC buck converter with high efficiency at light load using adaptive pulse modulation

Abstract: Reducing the number of large external components, especially inductors, is a very important issue for Power-Management ICs (PMICs). Single-Inductor Multiple-Output (SIMO) converters are excellent candidates to meet this requirement [1-3]. However, there are several issues with SIMO converters, such as cross regulation, instability and inefficiency at light load. Under normal load conditions, comparator-based controlled SIMO converters [1,2] show good cross regulation performance due to the fast response of the comparator. However, the switching loss remains constant and degrades light load efficiency due to the fixed switching frequency of output switches. The low-efficiency characteristic when any output is under light load condition is a critical issue that must be solved because a SIMO converter is very suitable for light load applications. In addition, the cross regulation issue appears again when any output is under no load because the output receives energy from the inductor every cycle despite the load condition. To solve these issues, a SIMO converter was previously reported to support Pulse Frequency Modulation (PFM) mode [3]. However, the mode change control method increases the complexity of the control loop, which makes it unsuitable for a multi-output SIMO converter. In this paper, an Error Based Controlled (EBC) SIMO converter is presented to resolve the problems raised above using load-dependent Adaptive Pulse Modulation (APM). A hybrid topology composed of a switching converter and a linear regulator is also presented to minimize the cross regulation issue. To highlight the advantages, a 10-output SIMO converter is designed.

Residual Amplitude Modulation Method Implemented at the Phase Quadrature Frequency of a 1650-nm Laser Diode for Line Shape Recovery of Methane

Abstract: This paper reports the extraction of concentration and pressure of methane using a 1650-nm laser diode operated at its phase quadrature frequency (f q ) and using the calibration-free residual amplitude modulation (RAM) method. Although the RAM method is the simplest calibration-free technique, it has low signal levels compared with the phasor decomposition (PD) method for small values of the phase difference ψ between the laser intensity modulation and frequency modulation (FM). For the laser diode used in this paper, ψ turned out to be 90° at a very modest modulation frequency of 125.5 kHz, which is an order of magnitude lower than values reported elsewhere. The RAM signal and FM signal are at phase quadrature at this frequency and each can be fully and simultaneously recovered along a detection axis of a lock-in amplifier free from distortion by the other. The absolute absorption profile is accurately recovered with the signal-to-noise ratio (SNR) maximized for this laser. The gas parameters are extracted by fitting a Voigt line shape to the experimental data. These results show that when operating at f q , the PD method offers no advantage over the RAM method and is therefore redundant. In addition, the background RAM is eliminated by an automatic fiber-optic RAM nulling technique. Finally, the RAM method is also implemented at high values of modulation index to increase the SNR ratio. The time resolution of measurements is currently 10 s. The prospect of using the RAM method with a 2004-nm vertical cavity surface emitting laser is also explored.

An Analog-Mode Impulse Radio System for Ultra-Low Power Short-Range Audio Streaming

Abstract: This paper introduces and analyzes an ultra-low power and low-complexity analog IR-UWB radio system for unlicensed audio streaming which achieves continuous wave FM performance but exploiting aggressively duty-cycled signaling. At the TX, signal is modulated using a VCO which generates pulses with variable rate (PRF modulation), for an average of $\sim$ 600 kHz. At the RX an asynchronous and interference-robust detector regenerates the modulated signal at half frequency without requiring phase-locking, which is successively processed by a passive FM detector. The obtained demodulated signal is filtered using a fourth order Sallen-Key cell. The TX and RX modules based on commercial components draw 1.89 and 10 mA from 100 mAh Lithium-ion rechargeable batteries (1 $\times$ TX and 2 $\times$ RX) and include an integrated TX/RX chipset in a 130 nm RFCMOS technology which operates at 3.5 GHz center frequency and 1.2 V supply. The radio system transmits audio with THD $ 1%, provides an SNR of 64 dB (aligned with FM radio and compact cassettes) and has a frequency response 110 Hz–17 kHz, for a continuous play time of 50 h (TX) and 12 h (RX), and 2.5 m radio range.

Isolated 100% PWM gate driver with auxiliary energy and bidirectional FM/AM signal transmission via single transformer

Abstract: Galvanic isolated gate drivers require a control signal as well as energy transmission from the control side (low-side) to the driver side (high-side) An additional backward signal transmission is preferred for error signals, status information, etc This is often realized by means of several transformers or opto-couplers Decreasing the number of isolation elements results in lower cost and a higher degree of miniaturization This work presents a gate driver with bidirectional signal transmission and energy transfer via one single transformer The key concept proposed in this paper is to combine bootstrapping to deliver the main gate charge for the driven power switch with additional energy transfer via the signal transformer This paper also presents a very efficient combination of energy transfer to two high-side supply rails with back channel amplitude modulation This way an isolated gate driver can be implemented that allows 100% pulse-width modulation (PWM) duty cycle at low complexity and system cost The proposed high-side driver IC with integrated power supply, modulation and demodulation circuits was manufactured in a 180nm high-voltage BiCMOS technology Measurements confirm the concept of bidirectional signal transmission with a 1MBit/s amplitude modulation, 10/20MHz frequency modulation and a maximum power transmission of 14mW via the transformer

The Questions of Circuitry Design when Forming the Switching Functions of the Control System of the Matrix Frequency Converter

Abstract: The switching function generator of the matrix frequency converter control system is described. This device can be used in the control systems of frequency-controlled AC drives and special consumers. The output voltage of the matrix frequency converter is generated by this device on the principle of amplitude modulation of the reference sinusoid by steps that are formed from the twelve-phase input voltage sections. The described device enables to generate the output voltage in the range from extremely low frequencies up to the frequency of 150 Hz. At the same time in the low frequency region up to 15 Hz the total harmonic distortion of output voltage complies with the value specified in GOST 13109-97. The frequency range above 15 Hz requires the use of pulse-width modulation to shift the higher harmonics to the high frequency region. The device design consisting of individual identical blocks allows simplifying the manufacturing process, and applying modular technology in the manufacture and maintenance of the device itself and the entire control system in general.

Pixel-Parallel 3-D Integrated CMOS Image Sensors With Pulse Frequency Modulation A/D Converters Developed by Direct Bonding of SOI Layers

Abstract: We have developed for the first time a 3-D integrated CMOS image sensor with pixel-parallel analog-to-digital converters (ADCs). Photodiode (PD) and inverter layers are prepared on separate silicon-on-insulator layers and directly bonded with damascened Au electrodes. The handle layer is then removed by grinding and XeF2 vapor phase etching to expose the PD surface. The developed process is suitable for pixelwise interconnection because it allows the damascened Au electrodes to be 1 $\mu \text{m}$ in diameter or less. An ADC circuit is designed based on pulse frequency modulation where pulses are generated proportional to the illumination intensity, and contains a PD, inverters, a reset transistor, and counters. A prototype 3-D integrated CMOS image sensor is also developed with 64 pixels, which acquires video images without pixel defects. A wide dynamic range of >80 dB is confirmed for the incident light intensity. The experimental results demonstrate the feasibility of pixel-level 3-D integration for high-performance CMOS image sensors.

Optimised phase disposition (PD) modulation of a modular multilevel converter using a state machine decoder

Abstract: This paper presents a theoretical harmonic analysis of phase disposition (PD) and phase shifted carrier (PSC) pulse width modulation (PWM) strategies for MMC converters. It is shown that when these strategies are implemented on a per MMC arm basis, their spectral performances converge because of cancellation of odd carrier sideband groups between each phase leg's arms. An improved PD modulation strategy is then presented that uses a single PD modulator for the entire phase leg, followed by a state machine decoder that evenly distributes switching pulses to all sub-modules across the phase leg upper and lower arms to balance the distribution of sub-module commutation events. The resulting strategy achieves optimum phase leg PD spectral performance, and also achieves natural voltage balancing of the MMC sub-modules. All theoretical findings are supported by simulation and experimental results obtained using a five level MMC prototype.

Reconstruction of input signal of sensor with frequency output

Abstract: The sensor with frequency output converts the measured quantity to the pulse signal, the instantaneous frequency of which is proportional to the instantaneous values of the input signal. Measurement of the pulse signal frequency is always a measurement of a mean value and direct measuring of its instantaneous value is not possible. The paper contains the analysis of the principles of operation of the frequency output sensor and an appropriate generalized flow chart. A processing algorithm allowing to reconstruct the input signal on the basis of digitally measured time intervals between the subsequent impulses of the output signal is presented. The suggested approach is presented using the example of an incremental rotary encoder and a Voltage-to-Frequency Converter.

Space vector PWM for a three-phase to six-phase direct AC/AC converter

Abstract: In this paper a generalized multi-phase space vector theory is considered for developing the space vector modulation of a three-phase to six-phase AC to AC converter. The modulation is based on the control of the voltage vectors in the first d-q plane, while imposing the remaining voltage vectors in the second and the third planes (x-y, 0+–0−), being zero. The duty cycles of the bidirectional switches are obtained using space vector modulation theory. The proposed converter system offers full control of the input power factor, no limitation on the output frequency range and nearly sinusoidal output voltage. The proposed space vector algorithm can be fully implemented on a digital platform. The theoretical analysis is confirmed by digital simulations which is further verified using real time implementation.

Simplified control for redistributive balancing systems using bidirectional flyback converters

Abstract: Battery stacks with many cells per string require sophisticated balancing hardware for capacity maximization, safe operation, and extended lifetime. This paper proposes a simplified control architecture for redistributive battery balancing topologies. A high level controller defines the link currents to be actuated by flyback DC/DC converters. Linear transformations are used to rewrite the balancing problem as a regulation problem that can be solved with a saturated LQR. To reduce the overall system complexity and cost, the low-level control requirements are minimized using feedforward approaches based on pulse width and pulse frequency modulation. The control system is developed using MATLAB/Simulink/PLECS and validated experimentally.

Liquid crystal display device and backlight control method thereof

Abstract: Provided are a liquid crystal display device and a backlight control method thereof. The liquid crystal display device comprises: an image data acquisition portion (10); a liquid crystal panel (20); a panel driving unit (30); a backlight module (40); and a backlight driving unit (50). The panel driving unit (30) drives the liquid crystal panel (20) according to image data (S RGB), and generates a backlight driving signal (S PWM) corresponding to the image data (S RGB). The backlight driving unit (50) comprises a pulse width modulation module (51) and a pulse frequency modulation module (52) which are used to respectively modulate the backlight driving signal (S PWM) so as to form driving power sources (VL1, VL2) and to supply the same to the backlight module (40). The liquid crystal display device further comprises a backlight modulation selection unit (60) for calculating an average pixel luminance value A of the image data (S RGB). A reference pixel luminance value A0 is set in the backlight modulation selection unit (60). When A≥A0, the backlight modulation selection unit (60) selects to turn on the pulse width modulation module (51). When A＜A0, the backlight modulation selection unit (60) selects to turn on the pulse frequency modulation module (52).

Combined amplitude-time modulation and phase modulation

Abstract: A method for generating a compound signal wave with one or more substantially sinusoidal waveform(s) containing an encoded digital information combined with a variable phase changing waveform(s) producing a compound notched sinusoid waveform including at least an amplitude-time modulated sine wave and at least one phase modulated wave(s). Presence or absence of change to a wave's sinusoidal amplitude within a phase indicates a data value. These data values can be changed within a data cycle or packet. Reduced modulation distortion is exhibited by amplitude-time modulation techniques when compared to classical amplitude modulation techniques. This reduced distortion in a communications signal results in increased effective transmission lengths, reduced error rates, higher data rates, and improved data security.

Supply-Modulated Radar Transmitters With Amplitude-Modulated Pulses

Abstract: This paper introduces an efficient radar transmitter with improved spectral confinement, enabled by a pulse waveform that contains both amplitude and frequency modulation. The theoretical behavior of the Class-B power amplifier (PA) under a Gaussian envelope is compared to that of a Class-A PA. Experimental validation is performed on a 4-W 10-GHz GaN monolithic microwave integrated circuit PA, biased in Class B with a power-added efficiency (PAE) of 50%. When driven with a Gaussian-like pulse envelope with a 5-MHz linear frequency modulation (LFM), the PA demonstrates a 31% average efficiency over the pulse duration. To improve the efficiency, a simple resonant supply modulator with a peak efficiency of 92% is used for the pulse Gaussian amplitude modulation, supplemented by pre-distortion on the PA input, while the LFM is provided through the PA input. This case results in a five-point improvement in system efficiency with an average ${\rm PAE}=40\hbox{\%}$ over the pulse duration for the PA alone, and with simultaneous 40-dB reduction in spectral emissions relative to a rectangular pulse with the same energy.

Feature Patterns Extraction-Based Amplitude/Frequency Modulation Model for Vortex Flow Sensor Output Signal

Abstract: To solve the key problem that vortex flowmeter is susceptible to be disturbed by pipe vibration, the collected data of the vortex flow sensor output signal are filtered, and the amplitudes of the filtered signal are extracted The fluctuations of both the amplitude and frequency are analyzed and compared so as to study antistrong vibration interference digital signal processing methods for vortex flowmeter The patterns of fluctuation features are extracted by calculating and analyzing the probability density function and the cycle differenced sequence Combining with the features of the amplitude modulation and frequency modulation, the mathematical models of the vortex signal, vibration interference, and cofrequency signal are built, and the patterns between the frequency and model parameters are obtained The effectiveness of the three types of signal models is verified through error analysis, then the reliability of the fluctuation patterns of signal amplitude and frequency is examined, which provides the basis for digital signal processing methods based on fluctuation features

Spectrum calculation of frequency pulse modulation voltage using double Fourier series

Abstract: The features of using double Fourier series for calculation spectrum of pulse-width modulated (PWM) signals are described. Restriction of implementation double Fourier series for signal with other type of modulation are indicated and approach for signals with arbitrary modulation on basis double Fourier series are proposed. The example of spectrum calculation of pulse-frequency signal (PFM) is demonstrated. Numerical check of calculation are performed.

Short pulse width stimulation

Abstract: A system example may include electrodes operationally positioned for use in delivering sub-perception neural modulation, a neural modulator configured to use at least some electrodes to generate a modulation field, and a feedback system configured to receive a feedback signal that a generated modulation field provides a perceived or measurable response. A control system may implement a calibration process including controlling the neural modulator to generate the modulation field using a first and second stimulus pulse with a first and second pulse width, respectively, and using the feedback system to determine a first and second reference point that represents an intensity of the modulation field generated using the first and second pulse widths, respectively, that provides the response, and deriving sub-perception calibration data specific to sub-perception modulation delivered using a sub-perception pulse with a sub-perception pulse width.