32 results about "Pulse interval modulation" patented technology

The invention discloses a method of modulating a variable pulse amplitude position and improving an error rate for a visible light communication system, belonging to the field of visible light wireless communication technologies. According to the method, modulation of the variable pulse amplitude position is utilized in a modulation module of a signal transmitting end, a modulation method is multi-system modulation capable of combining pulse amplitude position modulation and pulse width modulation, transmission of communication data is guaranteed while a system dimming function is provided, improvement of the communication quality mainly includes that the transmission rate can be improved under the condition of the same symbol rates, the advantages of high multi-system modulation bandwidth efficiency and high pulse position modulation power efficiency are combined, the spectral efficiency can be effectively improved, and compared with the other multi-system modulation manner, the complexity is lower. In order to further improve the error rate of the visible light communication system, the method utilizes a channel balancer based on a feed-forward back propagation multilayer perceptron on a receiving end, so that the error rate is effectively improved, and the communication quality is further improved.

The invention discloses a free space optical communication device based on a passive optical network (PON) technology, which aims at the situation that the current free space optical communication system is operated in an SDH system and is not suitable for a PON broadband access network technology. The free space optical communication device comprises a PON interface module, an optical emitting module, an optical emitting antenna, an optical receiving antenna, an optical receiving module, a system control module and an alignment module, wherein both the optical emitting module and the opticalreceiving module adopt infrared lasers with different wavelengths, which are respectively light with the wavelength of 850nm and light with the wavelength of 20nm, and the interference resistance andthe stability of the system are strengthened; the optical emitting module and the optical receiving module perform the transmission and the receiving by four beams of light and drive the lasers in a receiving channel by applying corresponding narrowband interference optical filters and a double-end pulse interval modulation drive circuit; the interference resistant effect of the device on severe weather is strengthened, and the device can be more favorably applied to the wireless communication of a Chinese PON broadband access network.

The invention discloses a controller used in an implanted medical instrument for patients, which pertains to the technical field of implanted medical instruments. The invention provides a controller for controlling the implanted medical instrument to set the operating status and simple parameters of the instrument for patients beyond the clinical treatment. The controller is characterized in that the controller for patients has an integrated structure with compact appearance and convenient operation and is mainly composed of a shell, keys, a display, cells, a printed circuit board, antenna, and the like; meanwhile, as the two-directional communication is realized in an internal implanted medical instrument by using a wireless ultra-wideband; as the communication adopts the PIM (Pulse Interval Modulation) regulation, the controller is high in control reliability and low in consumption, and can be widely applied to controlling the operation of various implanted medical instruments beyond the clinical treatment.

An embodiment of a control system for controlling operation of an electric motor includes a current command module configured to receive a torque command and output a current command, and a current controller module configured to generate a modulation index value based on the current command. The system also includes a signal generator configured to generate a voltage signal modulated via a pulse width modulation (PWM) scheme based on the modulation index value, the PWM scheme being a combination of a continuous PWM scheme and a non-continuous PWM scheme based on the modulation index value being greater than or equal to a first threshold value, the signal generator configured to output the voltage signal to the electric motor.

The invention provides a sliding-mode control method suitable for a nine-switch converter. Output current and midpoint voltage to earth are sampled, a sliding mode surface is obtained through operation on voltage and current sampled signals and corresponding instruction values and then sent into a sliding-mode control system, corresponding drive signals are provided according to the sliding-mode track state for controlling nine switching tube switches, the sliding-mode track is enabled to converge on the sliding mode surface, and finally two groups of three-phase sinusoidal current output by the nine-switch converter can be directly tracked and provided. According to the method, the output current is taken as a controlled object, the control method is more simple compared with voltage type modulation strategies such as pulse width modulation (PWM) and space vector pulse width modulation (SVPWM), the steady accuracy is high, and the dynamic response is rapid.

The invention discloses a nanosecond grade digital synchronizer based on a FPGA high-speed serial bus. The digital synchronizer comprises a starting signal module, a signal isolation module, a FPGA control time sequence module, a signal conversion module and a pulse signal output module which are electrically connected in order; the FPGA control time sequence module is connected with an upper computer through a 422 serial port module; the technical scheme implement the synchronous triggering and pulse width modulation of multipath pulses with delay precision of 1ns, the digital synchronizer is small in volume, wide in delay range, adjustable in pulse width, and capable of meeting different requirements of synchronous triggering of a plurality of large physical devices.

A Predictive Power Control (PPC) device within a TCON Bias IC that addresses an overdesign inefficiency and enables a low cost solution. A PPC block utilizes the next frame image data and interacts with a pulse width modulation (PWM) control block of internal regulators to proactively prepare the output voltages of a power regulator for the power requirements in one or more future frames, for example.

The invention relates to the technical field of acousto-optic communication, in particular to an aerial and underwater laser-induced acoustic communication device capable of improving the photoacoustic conversion efficiency and application thereof. A DHPIM double-head pulse interval modulation module, a laser excitation and scanning control module and a pulse CO2 laser which are connected in sequence are arranged in atransmitting mechanism, wherein optical signals output by the pulse CO2 laser are processed by a light beam shaping mechanism and then are transmitted through air, so that the laser signals interact with a water medium in an optical breakdown mode after reaching the water surface, and the laser pulse is converted into a sound wave signal to be propagated in all directions underwater; an underwater optical fiber hydrophone is arranged in a receiving mechanism, and the optical fiber hydrophone is used for receiving sound wave signals. Compared with the prior art, the probability of data loss or decoding can be effectively reduced; the transmission capacity and the bandwidth efficiency are improved, and the implementation complexity of the system is simplified.

The present invention discloses a power source chip. The power source chip comprises a substrate, a modulation controller disposed on the substrate, and a sensing module disposed on the substrate, wherein the modulation controller has a pulse width modulation mode and a pulse frequency modulation mode, and the sensing module is used for monitoring the output power of the power source chip; when the output power is greater than a power threshold value, the pulse width modulation mode is invoked, otherwise, the pulse frequency modulation mode is invoked; the magnitude of the output power is generally in linear correlation with the power of a load; and therefore, complicated calculation is not needed, and when the pulse width modulation mode and the pulse frequency modulation mode are selected, labor-saving and labor-saving performance can be realized. The invention also discloses an invocation method of the PWM (pulse width modulation) and PFM (pulse frequency modulation) of a power source chip and a display screen.

The invention relates to the field of numerical control laser processing, and provides a control method and a control system of pulse width modulation (PWM) signals and a numerical control laser processing machining tool. The control method of the PWM signals comprises the following steps: acquiring machine tool motion information and PWM signal configuration information, wherein the machine tool motion information comprises zone bit which shows machine tool motion state and analog quantity which changes in proportion with machine tool motion speeds, judging the machine tool motion state according to the zone bit, if the machine tool is in a motion state, the PWM signals are generated according to the analog quantity and the PWM signal configuration information; and if the machine tool is in a static state, the PWM signals are generated according to the PWM signal configuration information. A computer numerical control (CNC) system is used for directly controlling the PWM signals to control a system to carry out change of pulse signal frequency and duty cycle, delay of pulse signals is shortened, lag caused by programmable logic controller (PLC) cycle operation time is avoided, and cutting effect and cutting accuracy are improved effectively.

The invention discloses a fixed length dual-amplitude pulse interval modulation method for a wireless optical communication system. In the method, the length of each modulation symbol is fixed, and each modulation symbol comprises an starting pulse and a marker pulse; the starting pulse is fixedly started from a first time slot, and has fixed amplitude and width; and the width of the marker pulse is fixed, but the amplitude and the position of the marker pulse are determined by a denary value k corresponding to a bit array transmitting M-bit binary information. The method can shorten the length of symbols, improve bandwidth efficiency and transmission capacity and solve the problems of possible redundancy or overflow of a buffer in the modulation process and the like, and has the capacity of synchronizing built-in symbols at the same time.

The invention discloses a selective harmonic eliminated pulse width modulation-based DC bus voltage fluctuation compensation method. The method particularly involves control of a three-phase AC motordriving system and comprises the steps of determining a synchronous processing zone according to selective harmonic eliminated pulse width modulation (SHEPWM) switch angle distribution characteristicat different frequency division parameters; forecasting DC bus voltage waveform in the processing zone; and dividing the zone according to the forecasted waveform, and performing stator magnetic fluxerror accumulation according to switch moment corresponding to the zone. With the method proposed by the invention, the favorable harmonic characteristic of SHEPWM can be maintained, meanwhile, extraoutput voltage harmonic caused by DC bus voltage fluctuation is reduced to minimum, and the low-frequency harmonic current and the output torque fluctuation caused by the bus voltage fluctuation are substantially reduced; and the method can be directly used for an ordinary motor control system, and no extra hardware is needed.

The invention discloses a data transmission method based on pulse width modulation and a voice alarming fire disaster detector. A master control MCU is connected with a voice IC single I/O wire. The data transmission method based on pulse width modulation comprises the following steps of data conversion, wherein the master control MCU encodes a check bit and a command code in a data package into binary data; or, the master control MCU firstly generates a binary command bit through the command code in the data package, then adds the check bit according to the binary command code, and encodes the data package into the binary data; pulse width modulation, wherein the binary data are sequentially modulated into one-to-one-correspondence pulse units according to bits, when the bit is zero, the binary data are converted into pulse units with the pulse width of T1, and when the bit is one, the binary data are converted into pulse units with the pulse width of T2; pulse signal sending, wherein the master control MCU enables the pulse units to form pulse signals with the pulse interval of T3 and sends the pulse signals to a voice IC through a single wire; data receiving, wherein the voice IC obtains the pulse signals and restores the data package according to the pulse width.

Briefly, in accordance with one or more embodiments, a digital transmitter may comprise two or more phase modulators in a cascaded arrangement. The phase modulators may modulate a local oscillator signal using control signals derived from the quadrature baseband data to be transmitted. A closed loop power control feedback arrangement may be used to compare the output power of the transmitter with a desired output signal, and make corrections to the output signal by modifying at least one of the control signals provided to the cascaded phase modulators.