579 results about "Pulse-position modulation" patented technology

Embedded piezoelectric sensors in large civil structures for structural health monitoring applications require data communication capabilities to effectively transmit information regarding the structure's integrity between sensor nodes and to the central processing unit. Conventional communication modalities include electromagnetic waves or acoustical waves. While guided elastic waves can propagate over long distances on solid structures, their multi-modal and dispersive characteristics make it difficult to interpret the channel responses and to transfer useful information along pipes. Time reversal is an adaptive transmission method that can improve the spatiotemporal wave focusing. The present disclosure presents the basic principles of a time reversal based pulse position modulation (TR-PPM) method and demonstrates TR-PPM data communication by simulation. The present disclosure also experimentally demonstrates data communication with TR-PPM on pipes. Simulated and experimental results demonstrate that TR-PPM for data communications can be achieved successfully using guided elastic waves.

The problem of charge leakage in the AC compensation filter for the error amplifier of a pulse width modulation (PWM)-based DC—DC converter is effectively obviated by controllably sampling and storing the voltage across the AC compensation filter, in response to a transition of the operation of a DC power supply from run or active mode to quiescent or sleep mode. The sampled voltage is retained as a compensation voltage throughout the quiescent mode, so that it will be immediately available to the PWM circuitry at the termination of the quiescent interval. This serves to ensure a relatively smooth (low noise) power supply switch-over during a subsequent transition from quiescent to active mode.

A method of balancing the voltage of DC links in a cascaded multi-level converter (CMC) semiconductor circuit, including the steps of providing a plurality of H-bridge converters per phase in the CMC circuit and utilizing a three phase duty cycle value from the main controller to determine a normalized duty cycle value, a ceiling duty cycle value and a floor duty cycle value. The normalized duty cycle value and an output current of the CMC is used to determine the direction and polarity of a capacitor current, and utilizing the capacitor current to determine a plurality of output capacitor voltages. A voltage summation result and direction is obtained from a ceiling index pointer and a floor index pointer and the voltage summation result, direction from the ceiling index pointer and a floor index pointer are used to create a combined switching table for the H-bridge converters. A pulse width modulator is utilized to balance the voltage of the DC links and thereby eliminate DC-capacitor voltage imbalance.

The invention discloses a percutaneous closed-loop control charging device for implantation type medical treatment instrument and belongs to the technical field of implantation medical instrument. The percutaneous closed-loop control charging device for implantation type medical treatment instrument comprises an external charger and an internal implantation type medical instrument. An external energy transmitting coil is a large-size flat magnetic core coil, and an internal energy receiving coil is a hollow coil; the external energy transmitting coil transmits electromagnetic energy by adopting a resonance electromagnetic coupling manner with parallel central shafts; and the electrical energy obtained by the internal energy receiving coil charges an internal rechargeable battery through an internal charge control circuit. The closed-loop control charging device communicates in a pulse position modulation manner for closed-loop control to ensure the energy received by the implantation medical instrument in different charging phases to be within the normal range, effectively control the heating and increase the safety; the closed-loop control charging device calculates the efficiency by the internal feedback parameter to realize counterpoint prompt and increase the charging efficiency. The percutaneous wireless charging method can charge the implantation type medical instrument by a titanium casing, is safe and reliable in charging, and can be applied to all types of implantation type medical instruments equivalent to a deep brain stimulator in power level.

Methods and systems for generating a variable spacing pulse position modulated (VSPPM) signal for transmission across an ultra-wideband communications channel. The variable pulse position modulated spread spectrum signal is created by encoding every M input data bits from an input data stream into a symbol consisting of Nc chips. Each chip is divided into 2M sub-chips and each sub-chip is further divided into Np time slots. A pulse is transmitted for each chip in the symbol. During each chip period, the pulse is placed in the sub-chip corresponding to the binary M-tuple (or symbol) value. A time hopping code sequence consisting of Nc elements with a one-to-one chip association is then applied to each symbol so that the position of each pulse is shifted to the appropriate time slot that corresponds to the time hopping code value.

A DC (direct current) converter includes a PWM (pulse width modulation) pulse generation unit outputting a PWM pulse signal whose duty ratio is controlled in accordance with an output voltage, a PFM (pulse frequency modulation) pulse generation unit outputting a PFM pulse signal whose pulse output interval is controlled in accordance with an output voltage, a selection circuit selecting and outputting any one of the PWM pulse signal and the PFM pulse signal in response to a selection signal, a drive circuit unit driving a load and generating an output voltage on the basis of a signal outputted from the selection circuit, and a switching control unit outputting the selection signal. When the selection signal is in a second state, the switching control unit detects a fact that the number of pulses of the PFM pulse signal in a measurement period increases to or above a set value of the maximum number of pulses, and switches the selection signal to a first state.

An impulse radio-based ultra wideband communication system, using an ultra wideband impulse and a 1-bit high-speed digital sampler, includes a transmitting RF module, a receiving RF module, a signal recovery unit, a transmitting signal processor, a receiving signal processor, and an ultra wideband antenna. The transmitting RF module includes an integrated impulse generator capable of implementing on-off-keying modulation and pulse position modulation, and an amplifier for amplifying output of the integrated impulse generator. The receiving RF module includes a two stage envelope detector for detecting a received signal and a comparator for converting the detected signal into a rectangular pulse. The signal recovery unit restores the signal from the receiving RF module to a digital signal using the 1-bit digital sampler. The signal processor includes a receiving signal processor for synchronizing the digital signal and decoding the detected signal. The ultra wideband antenna transmits and receives an ultra wideband signal.

Methods and systems for processing an analog signal that is generated by a high energy photon detector in response to a high energy photon interaction. A digital edge is generated representing the time of the interaction along a first path, and the energy of the interaction is encoded as a delay from the digital edge along a second path. The generated digital edge and the delay encode the time and energy of the analog signal using pulse width modulation.

In a display device capable of low power and multi-color displaying without raising a frame rate due to increase of display gradations in number by combining a gradation representation through a FRC and a gradation representation system using a pulse width modulation or pulse height modulation method, the gradation representation is executed by a method of pulse width or pulse height modulation in one frame using lower significant N bits to a video signal of M bits, and the display of the gradations is performed by the FRC of the present invention using more significant M−N bits and further using 2M−N−1 frames, and thus the number of the frames required for FRC is reduced to decrease a frame frequency to thereby realize a gradation display with reduction of electric power and suppression of flickers.

Decreasing the average transmitted power in an optical fiber communication channel using multilevel amplitude modulation in conjunction with Pulse Position Modulation (PPM). This multilevel PPM method does not entail any tradeoff between decreased power per channel and channel bandwidth, enabling a lower average transmitted power compared to On / Off Keying (OOK) with no reduction in aggregate data rate. Therefore, multilevel PPM can be used in high-speed Dense Wavelength Division Multiplexed (DWDM) systems where the maximum number of channels is traditionally limited by nonlinear effects such as self-phase modulation (SPM), cross-phase modulation (XPM), four-wave mixing (FWM), stimulated Brillouin scattering (SBS), and stimulated Raman scattering (SRS). This modulation technique can enable an increased number of channels in DWDM systems, thereby increasing aggregate data rates within those systems.

A radio-frequency-identification (RFID) system includes an RFID tag and an RFID reader, where the RFID reader is configured to communicate with the RFID tag using time-hopped pulse-position modulation and ultra-wideband modulation. The time-hopped pulse-position modulation includes sending from the RFID tag to the RFID reader a series of pulses in time slots selected by the RFID tag through a cryptographically secure pseudo-random generator.

A method of controlling an output voltage of a pulse width modulation (PWM) converter with a PWM signal driving a power switch of the converter may include using a comparator to compare a reference voltage with a scaled output voltage of the converter, incrementing or decrementing an up / down counter at each pulse of a clock signal applied to the counter depending on a state of the comparator, and controlling the comparator to generate the PWM signal with a control voltage selected from a look-up table using a value of the counter.

A transmitting controller is connected to a powerline and on command places a reference signal and a series of signal pulses in the powerline at a series of signal timing positions related to zero voltage crossing points so that the signals pulses are substantially in the powerline temporal quiet zone near zero crossing. The signal pulses are produced from a pair of capacitors and switches which are each sequentially charged a first polarity from the powerline and is discharged in the powerline at the opposite polarity so that the powerline voltage at the time of the pulse is additive to the pulse voltage. The receiving controller is connected to the powerline and has a filter circuit therein which filters away the powerline AC signal and noise to leave the reference and signal pulses. The signal pulses are compared to the position of starting reference pulses to determine in which signal timing position the pulses have occurred.

A boost DC / DC converter, including a mask circuit, a switched boost circuit, a pulse width modulation (PWM) circuit and an AND gate, is provided. The mask circuit is used to output a mask signal according to a load current. In the present invention, the system can selectively operate in the pulse width modulation mode, the pulse frequency modulation (PFM) mode or the mixed pulse mask mode according to the mask signal corresponding to the load current when the system is under light load, medium load or heavy load respectively, so as to achieve optimal system efficiency.

The invention discloses a vehicle-mounted Doppler laser radar distance measuring method. A pulse separation module stores the number of transmission pulses and pulse separation information. A drive module decides the laser activation pulse transmission time according to the pulse separation information. The laser transmission pulses are projected to a lens through a beam splitter 100-percent passing light path and transmitted to a target through the lens in a collimation mode. Optical signals reflected by the target are collected through the lens and arrive at a photoelectric converter through a beam splitter 100-percent reflecting light path. The optical signals are converted into electric signals through the photoelectric converter. A signal processing unit module carries out pulse position modulation processing on the electric signals generated by the photoelectric converter through the pulse separation information, and the distance of the target is worked out. The vehicle-mounted Doppler laser radar distance measuring method has the advantages that the transmission pulse separation is modulated and adjusted through the pulse position at a vehicle-mounted Doppler laser radar transmitting end, a receiving end measures the road target distance through an improved data integration method, and the miniature of vehicle-mounted laser radar is achieved while the length of transmitted signals meets the high-speed scanning requirement.

A pseudo-chaotic coding / modulation method. The coding method exploits symbolic dynamics of a chaotic map at the transmitter to encode data. The encoding synthesizes the chaotic map based upon the data to be transmitted. In a preferred embodiment, pseudo-chaotic iterates are generated from a digital implementation of a Bernoulli shift map. The output of the shift map is translated by a mapping, preferably implemented by a digital signal processor, to allow transitions between states in a transmitted signal to differ, and the translated map is used to drive a modulator (for example PPM, FSK, PSK, QAM, etc.). In the specific case of pulse-position modulation (PPM) the translated map is used to modulate pulse train positions within a periodic synchronization frame. The preferred embodiment uses a shift register to implement an approximation of the Bernoulli shift map acting as a form of convolutional code with a number of states equal to the symbolic states defined on the chaotic map. A receiver may use fewer states and still decode the data signal, allowing receiver scalability.

Pulse width modulation is provided for controlling a resonant power converter, particularly for dimming of light emitting diode arrays without loss of efficiency. Dynamic oscillation due to the beginning of a pulse width modulated pulse burst is limited by shortening of the first and / or last pulse of a pulse bust such that the first pulse of a subsequent pulse burst close to or to connect with a full load steady-state voltage / current trajectory of the power converter. Pulse shortening made be made substantially exact to virtually eliminate dynamic oscillation but substantial reduction in dynamic oscillation is provided if inexact or even performed randomly.

The invention provides a pulse width modulation switching power supply controller and a switching power supply and belongs to the technical field of electronic integrated circuits. The pulse width modulation switching power supply controller and the switching power supply are widely applied to a PWM (Pulse Width Modulation) mode AC / DC (Alternating Current / Direct Current) switching power supply system. The PWM controller comprises an FB (Feed Back) sampling circuit, a current mode selecting circuit, a square wave generating circuit and the like. The pulse width modulation switching power supply controller has the advantages of being capable of achieving self-adaption of the system working frequency under different loads and reducing standby power consumption of the switching power supply.

Present invention discloses pulse number modulation based atmospheric pressure glow discharge control method and circuit. Control method adopts pulse density modulation to generate alternate presented square wave pulsing signal to control inversion circuit switch tube on / off in glow discharge main circuit, each working period containing fixed quantitative square wave pulse, through keeping working period unchanged and changing working period square wave pulse number to control inversion circuit feeding energy time to load, realizing atmospheric pressure glow discharge load fixed frequently constant voltage control. The present invention can realize frequency follow-up control and linear power regulation to atmospheric pressure glow discharge type nonlinear variational capacitive loading.

In some embodiments, an apparatus and a system, as well as a method and an article, may operate to transmit and receive data. Transmission may comprise transforming larger values of acquired data into smaller values of transformed data using a transform defined by a seed value selected to reduce digital pulse position modulation transmission time for the acquired data. Additional activities include digital pulse position modulating the transformed data and a checksum associated with the transformed data to provide a propagation signal, and transmitting the propagation signal into drilling fluid or a geological formation. Reception may comprise receiving the propagation signal, demodulating the propagation signal to extract the transformed data and the checksum, and transforming the transformed data into an estimate of the acquired data, using the transform defined by the seed value validated by the checksum. Additional apparatus, systems, and methods are described.

A method and system for providing pulsed power and data from a main control unit to slave units via a first bus. The main control unit has an AC signal generator for providing a plurality of first pulses (P1) on the bus for providing the power to the slave units. Each slave unit is AC-coupled to the bus via a first series capacitor arranged for converting the first pulses (P1) into second pulses (P2). Data communication from the main control unit to the slave units is established by modulating the first pulses (P1), and by demodulating the second pulses (P2). The modulation may be based on Pulse Position Modulation, Pulse Width Modulation, Pulse Count Modulation, Pulse Amplitude modulation. Zero, one or more bits may be communicated per first pulse. Optionally the slave units may communicate to the main control unit via a second bus.

A digital technique for pulse width modulation (PWM) utilizes a tapped delay line 304 receiving a reference clock and generating a plurality of time delayed reference clock transitions having finer time resolution than the reference clock signal. A multiplexer 120 receives the plurality of time delayed reference clock transitions as an input thereto and producing an output when one of the plurality of time delayed reference clock transitions is addressed. An accumulator circuit 524 generates control timing signals associated with the input signal sampling rate Fsample that are used to select outputs from the delay line 304 representing a pulse width modulated output signal.

A gradient amplifier system comprises a power level, a gradient coil and a controller level, wherein the power level comprises a plurality of bridge amplifiers which are operated at first switching frequency, the gradient coil is coupled to the power level and configured to generate a magnetic field which is proportional to coil current signals supplied by the power level, and the controller level is coupled to the input end of the power level and configured to generate gating signals of the pulse width modulation on basis of the coil current signals and reference current signals. When the conversion rate which is relative to the reference current signals and occurs in at least a first time period is lower than the preset threshold rate, the gating signals of the pulse width modulation are generated at second switching frequency, and the generated gating signals of the pulse width modulation are applied to the power level to switch the operating frequency of every bridge amplifier from the first switching frequency to the second switching frequency.

The invention discloses a pulse width modulation (PWM) rectification, variable-voltage and variable-current pulse charging system of an electric vehicle and belongs to a large-size storage battery charging system. The system comprises a rectification module, a charging module and a direct current charging management module; the rectification module is respectively connected with an alternating current power grid and the charging module; the charging module consists of a direct current input module and a direct current output module; the rectification module, the direct current input module, the direct current output module and the direct current charging management module are mutually-independent modules and are contacted together through network buses. The PWM rectification, variable-voltage and variable-current pulse charging system of the electric vehicle has a simple structure, a small size and wide application ranges, can be applied to the charging of all lead-zinc storage batteries, and is applicable for large-scale promotion. Moreover, the charging time of the storage batteries is greatly shortened.