397 results about "Wave modulation" patented technology

The present invention provides a spread spectrum clock generator that is capable of preventing phase jumps and jitters and suppressing the occurrence of Electro Magnetic Interference components and that can easily be applied to large scale integrated circuits. The spread spectrum clock generator can be configured with a filter, quantizer, fractional divider, and other elements. Also, this clock generator circuitry can be configured by combination of a delta-sigma ΔΣ quantizer and factional divider so that sine wave modulation and random number modulation can be realized. Thereby, control with digital values can be performed. This clock generator prevents precipitous phase variations in the output high frequency clock and makes fine phase control possible. Consequently, EMI reduction by 20-30 dB can be expected.

The invention relates to a generation and capture system of an encrypted frame hopping spread spectrum signal of an air fleet link, belonging to the technical field of aeronautical data link and radio navigation. The invention discloses a system framework of an encrypted frame hopping spread spectrum signal generation and capture method which can be implemented on a digital signal processor (DSP)and a FPGA (field programmable gate array) of a circuit board, and provides a baseband signal generation algorithm of an encrypted frame hopping spread spectrum system to replace a traditional long periodic sequence spread spectrum code and a compound pseudo code by absorbing the advantages of the easy capture of the compound pseudo code and the difficult breaking of the long periodic sequence spread spectrum code; and meanwhile, the invention provides two advanced and high-performance encrypted frame hopping spread spectrum signal capture algorithms, i.e. a frequency domain parallel capture method of the encrypted frame hopping spread spectrum signal of based on a FFT (fast fourier transform algorithm) and a direct capture method of the encrypted frame hopping spread spectrum signal based on a matching filter and the FFT. The invention solves the problem of difficult capture of the traditional long periodic sequence spread spectrum code. The method can be widely applied to satellite navigation receivers, range measurement systems and communication systems based on a quiescent carrier modulation direct sequence spread spectrum system.

The invention discloses an SF6 decomposition gas infrared spectrum multi-component detection method and a device. According to the method, a chopped wave modulation wheel and a spectroscopical filtration wheel in a traditional non-dispersion infrared spectrum technology are combined into a whole, a modulation filtration wheel is utilized to realize simultaneous measurement of multi-component gas,and a long path multiple reflection absorption technology is combined simultaneously to increase detection sensitivity. The device comprises an optics unit, a gas circuit unit and an electronics unitarranged in a main machine box. The SF6 decomposition gas infrared spectrum multi-component detection method and the device are suitable for electrical equipment fault monitoring and diagnosing in anelectrical system with SF6 gas being an insulation and arc extinction medium. On-line gas concentration measurement with high speed, high sensitivity and non-interference is realized.

The invention provides a non-sinusoidal time domain orthogonal modulation method which is non-sinusoidal wave modulation based on orthogonal pulse transmission information. Signals to be transmitted are modulated onto a time domain orthogonal impulse group and impulse parameters are regulated to realize the spectrum shifting and the spectrum control of the modulated signals. The modulated signals are band-limited signals, the spectrum characteristic of which can be controlled. The modulated signals can be applied to any communication frequency band. Communication with relative large bandwidth or broadband communication can be realized, and communication with relative small bandwidth or narrowband communication can be realized. In spectrum management, the method can be compatible with an existing frequency band-division and channel-division communication mode of a relative small bandwidth communication system. And the frequency band utilization rate of the system can infinitely approach Nyquist rate with the increase of orthogonal impulses.

The invention relates to a high power LED drive circuit with the emergency function, comprising a rectifying and filtering unit, a reverse excitation unit, a constant current driving unit and an emergency unit, wherein the rectifying and filtering unit is connected with the input end of the LED drive circuit and is used for rectifying and filtering the input alternating current signals; the reverse excitation unit is connected with the rectifying and filtering unit and is used for PWM wave modulation according to load change; the constant current driving unit is connected with the reverse excitation unit and is used for driving the LED to work at constant current; and the emergency unit is connected with the reverse excitation unit and provides power to the constant current driving unit when no alternating current input is detected by detecting the current of the reverse excitation unit. The LED drive circuit is simple and can automatically switch to the emergency power supply so as not to go out even though the mains supply has failure. The leakage current of the cells in the circuit is almost zero, thus ensuring the standby working time of the cells.

The invention provides a programmable optical component based on a scattering medium, an optical field regulation system, and an optical field regulation method, and solves technical problems that a conventional optical component has single function, is high in optical wave modulation cost, has complex apparatus and low integration degree. The system in the invention is successively provided with a light source beam expanding module, a modulation module, a scattering medium microscopic module and a detection module, a data processing module arranged between the modulation module and the detection module. A computer circularly controls a space light modulator to modulate an input optical field, and a detector detects an output optical field; then data shaping is carried out and an optical transmission matrix of the scattering medium is detected; and then a programmable optical component is constructed so as to achieve optical field regulation with methods such as optical phase conjugation, phase retrieval, speckle reconstruction and the like, wherein the optical field regulation includes imaging, chromatic dispersion, abnormal chromatic dispersion, focusing, shaping, etc. The programmable optical component and the system are intelligent, multi-functional, low-cost, easy to operate, highly integrated and strong in operability, and can be applied to the scientific research fields such as military science, bio-medicines, integrated optic, nano photonics, etc.

The invention relates to a method and a system for improving phase stability of a photon microwave signal. The method comprises the following steps that: light output by a laser device is divided into two beams of vertical polarized light by a polarized light beam splitter; a reference light is combined with transmission light via a polarized light beam combiner after frequency-shift, and passes through the polarized light beam splitter after passing through a light micro-wave modulation and a light delay link, finally the reference light is interfered by the transmission light after being rotated and polarized by a faraday rotation mirror, and then a beat frequency signal is detected through a low-speed photodetector; the beat frequency signal is subjected to phase comparison with a 25MHz reference signal to obtain a phase disturbance situation of a transmission system, and the signal output by a phase discriminator is used as a control signal of a microwave photonic phase shifter after being processed. The system comprises a DFB (distributed feedback) laser device, the polarized light beam splitter, an acoustooptic frequency shifter, the polarized light beam combiner, an RF (radio frequency) signal generator, a Mach-Zehnder modulator, the photon microwave signal phase shifter, the polarized light beam splitter, an optical interferometer, a low-frequency optical receiver phase discriminator and a proportion integrator.

A digital-to-analog converter (“DAC”) system utilizes chopping modulation technology to remove 1/f and other baseband noise from a baseband of a signal of interest. Chopping modulation and demodulation circuitry of the DAC operate at a chopping frequency equal to approximately one-half of a digital input signal sampling frequency. Chopping at one-half the sampling frequency allows fold back into the baseband of the input signal's frequency components and reduces fold back of noise, such as quantization noise, residing outside the baseband. In a further embodiment, a notch filter attenuates signals having frequencies around the chopping frequency prior to chopping to reduce fold back of noise into the baseband due to parasitic modulation. Coordination of chopping timing also reduces noises in the output of the DAC system.

For transmitting data, a receiving/backscattering arrangement receives, modulates and reflects or backscatters electromagnetic waves emitted by a base station. The modulation corresponds to the data to be transmitted and is carried out selectively using first and/or second different modulation methods depending on the received field strength of the received electromagnetic waves. Preferably, phase shift keying is used especially or at least at low field strengths at far range, while amplitude shift keying is used additionally or alternatively for high field strengths at close range. The two modulation methods can be superimposed. A circuit arrangement includes two different modulator arrangements to perform the two modulation methods depending on the received field strength. The second modulator arrangement preferably comprises a multi-stage voltage multiplier circuit with a modulated switching device intervening in one of the stages to achieve the modulation.

The invention provides an artificial super-surface electromagnetic wave amplitude modulator based on graphene, and mainly solves the problems of small modulation scope and narrow modulation bandwidth of a conventional electromagnetic wave amplitude modulator. The artificial super-surface electromagnetic wave amplitude modulator comprises a DC power supply and a frequency selection surface, three layers of dielectric substrates and a reflecting plate laminated from top to bottom sequentially, wherein a dielectric layer with relative dielectric constant less than three is arranged between the second dielectric layer and a reflecting plate to expand wave absorption bandwidth, the frequency selection surface is formed by m*n cross period units, a rectangular-ring metal paster embedded in a graphene film is arranged in the center of each cross period unit, metallic branches are connected to the upper and lower sides of the rectangular-ring metal paster, and the horizontal metallic fine leads connect the single cross units in an entire row into one body. The structure is simple, and metal pasters embedded in the graphene films are used to widen the modulation bandwidth and increase the reflection wave modulation amplitude. The reflecting plate with high conductivity is used to reduce the transmission of electromagnetic waves by a wave absorption device. The artificial super-surface electromagnetic wave amplitude modulator is applicable to active electromagnetic hiding and electro-optical switch equipment.

The invention relates to a driving system of a stepping motor with the current negative feedback, which is characterized in that: external signals pass through an optoelectronic isolating circuit and then are inputted into a control circuit. According to the detected signals, the control circuit generates four channels of input signals of A, /A, B and /B; the four channels of the signals, together with two channels of complementary and unipolar PWM waves which are generated by a PWM wave modulation circuit, enter a logic composite circuit, and then the logic composite circuit generates eight channels of outputs and the eight channels of the outputs are sent to a power driving circuit; the power driving circuit inputs control signals into the stepping motor; meanwhile, return signals on a sampling resistance respectively pass through a current negative feedback circuit to adjust the PWM wave modulation circuit, and pass through a current protection circuit to adjust the control circuit. The driving system of the invention has the advantages that a feedback element is added into the previous driving system of the stepping motor to ensure the steady phase current within a certain frequency ranges so as to realize the steady load capacity and more stable operation.

The invention discloses a simulation method of a bistatic synthetic aperture radar sea wave direction spectrum, which comprises the following steps of calculating a JONSWAP sea wave spectrum and a sea wave vertical displacement according to sea wave parameters; obtaining BiSAR echo signals comprising sea wave orbital velocity and accelerated velocity according to a radar wave modulation principle and BiSAR system parameters; carrying the matched filtering on the echo signals according to a BiSAR distance and Doppler imaging algorithm to obtain an analysis formula of a BiSAR sea wave image; working out the BiSAR sea wave image by adopting a numerical integration method; and at last, carrying out two-dimensional FFT operation on the BiSAR sea wave image to obtain the BiSAR sea wave direction spectrum. The BiSAR sea wave image can be worked out by adopting the numerical integration method without producing the echo signals and processing the image in a time domain, therefore, the invention has higher operation efficiency.

The invention discloses a high-voltage high-capacity impulse voltage generator. The impulse voltage generator comprises a charging capacitor, a wave head resistance, a wave tail resistance, a voltage divider, a load and a sphere gap; the impulse voltage generator is provided with a plurality of impulse voltage generating units consisting of the charging capacitor, the wave head resistor and the wave tail resistor; and the wave head resistor is arranged in a discharging loop. The impulse voltage generator is characterized in that: in partial or all impulse voltage generating units, wave modulation capacitors are arranged in parallel at two ends of the wave head resistor. The generator overcomes the defect that the wave modulation resistor of the traditional method cannot generate standard thunder impulse, can effectively inhibit adverse effect generated by stray inductance, and generates standard thunder impulse voltage; and the generator can generate the standard thunder impulse by increasing a few elements based on the conventional equipment, and has the advantages of small volume, low cost and the like.

The invention discloses a microstrip resonance structure Terahertz wave modulation apparatus and the method thereof. The apparatus comprises a Terahertz wave source, a microstrip resonance structure array, a high-resistance silicon substrate, a Terahertz wave detector and a modulatable semiconductor laser; the microstrip resonance structure array is sputtered on the high-resistance silicon substrate; the Terahertz wav from the Terahertz wave source is propagated to the microstrip resonance structure array, and is propagated out through the Terahertz wave detector by the Terahertz wave modulated by the high resistance silicon substrate; the modulatable semiconductor laser is disposed on the same direction of the Terahertz wave source; the included angle between the laser shot direction of the modulatable semiconductor laser and the incidence direction of the Terahertz wave from the Terahertz wave source is 0-30 degrees; and the microstrip resonance structure array is composed by a plurality of microstrip resonance structure units. The invention achieves the advantages of high modulation speed, large modulation bandwidth, small size, compact, easily machined, and simple and convenient operation; is not sensitive to Terahertz wave, can meet the high speed communication demand of Terahertz wave.

The invention discloses a modulation method of a three-phase Z-source neutral point clamped multi-level photovoltaic inverter. The method comprises the following steps of: obtaining line voltage signals Vac*, Vba* and Vcb* through initial modulating waves Va*, Vb* and Vc* and multiplying by a coefficient K respectively; obtaining a zero sequence signal v0 through a zero sequence signal calculating unit; adding zero-sequence signal with KVac*, KVba* and KVcb* to obtain final modulating waves Va**, Vb**, and Vc**, and comparing the modulating waves Va**, Vb** and Vc** with a carrier wave to obtain logical signals Sa, Sb and Sc; comparing the carrier wave with VH and VL to obtain a through connect signal ST; and making the logical signals Sa, Sb and Sc and the through connect signal ST pass through a logic circuit to obtain a switching signal. The invention has the beneficial effects that a single-carrier-wave modulation method is provided, so that the problem of excessive complexity in realizing the conventional multi-carrier-wave modulation and space vector modulation is solved; and meanwhile, the common-mode voltage of a system is kept constant, so that the drain current of the system is effectively restrained. A switching signal generating circuit is simple in structure, and can be realized by adopting an analog circuit as well as a digital circuit.

The present invention discloses a real-time normalization apparatus and method of the PGC demodulation in a sinusoidal phase modulation interferometer. An optical setup containing a measuring interferometer and a monitoring interferometer is constructed. An electro-optic phase modulator is placed in the common reference arm of the two interferometers. High-frequency sinusoidal wave modulation and low-frequency triangular wave modulation are applied to the electro-optic phase modulator at the same time. Sinusoidal modulation is used for generating phase carrier, and PGC demodulation is performed to obtain quadrature signals containing the phase information to be measured. Triangular wave modulation makes the quadrature signals change periodically. Ellipse fitting is performed on the Lissajous figure corresponding to the quadrature signals, and real-time normalization of the PGC demodulated quadrature signals is achieved. By calculating the variation of the phase difference between the two interference signals, the measured displacement is obtained, and nanometer scale displacement measurement is achieved.

The invention discloses an optical fiber ring eigen frequency measurement device and method based on sine wave modulation and second harmonic detection. According to the optical fiber ring eigen frequency measurement device and method, modulation is applied to by adopting a sine wave, and a second harmonic amplitude in an output signal is interfered through detecting an optical fiber ring, thus an eigen frequency is measured. The optical fiber ring eigen frequency measurement device has the technical effect that the modulation is applied by using the sine wave instead of a square wave, multiple defects caused by modulation of the square wave are overcome, the amplitude of the second harmonic of the output signal is detected, and high signal to noise ratio can be obtained by adopting a correlation detection technology.

This invention discloses one photon crystal Hertz wave modulation device and its method, wherein, the device comprises silicon photon crystal with deficiency, electrode, liquid crystal, silica dioxide underlay; the underlay is set with silicon photon crystal on and injects liquid crystal into silicon photon crystal holes with deficiency and sets electrode on both sides of silicon photon crystal with deficiency; The photon crystal Hertz wave modulation method is to use photon edge to modulate Hertz wave signals.

The invention discloses an electric bicycle control method based on the internal model principle. The method includes that the internal model principle is utilized to design a current loop controller to enable motor phase current to track the given sine wave signals. A speed given value is processed by a speed loop controller to serve as a current ring given amplitude, three ways of Hall sensor signals are calculated through a rotor section to obtain the period and the phase given by a current ring. Six ways of sine modulation signals are output from the current ring output through the wave modulation link to drive a three-phase voltage inverter to further enable a motor to run stably and efficiently. The method has the advantage sine phase current passes through a three-phase motor winding during operation of the motor. Compared with the traditional square wave control, the effects of small torque pulsation, low operation noise and long motor service life are achieved. The three-phase current is sine wave with the same phase as the three-phase counter electromotive force, the phase compensation link in traditional sine wave modulation is omitted, and the motor operation efficiency is improved. No complex coordinate transformation is required, the algorithm is simple and easy to achieve, and the requirement for controller is low.