63results about How to "High modulation accuracy" patented technology

The microwave transmitter of the present invention can perform two-terminal dynamic modulation with respect to the voltage supply terminal and the RF input terminal of a RF power amplifier. The microwave transmitter of the present invention comprises a first modulator and a second modulator. The first modulator uses the baseband digital delta-sigma modulation technique to process the envelope signal and outputs this signal to the voltage supply terminal of the RF power amplifier as a supply voltage. The second modulator uses the baseband digital pre-distortion technique to process the IQ-modulated carrier and outputs this signal to the RF input terminal of the RF power amplifier as a RF input signal. Thereby, the RF power amplifier can highly efficiently reconstruct the power-amplified RF modulated carrier without distortion at the RF output terminal. In addition, the baseband digital processing techniques used in the two modulators make the microwave transmitter of the present invention suitable for multi-mode operation.

An object of the invention is to provide wideband modulator using a PLL synthesizer which can match the frequency characteristic and prevent degradation in modulation accuracy even in the presence of a variation in the manufacture of circuit components. In a wideband modulator which modulates the division ratio of a frequency divider by using a modulating signal generated by a modulating signal generator and outputs a modulated carrier signal from a VCO, first and second calibration data from a calibration data generator are input via a selector. The amplitude value of an ac component of each modulating signal appearing on the output of a loop filter or the amplitude value of an ac component of each modulating signal demodulated by a demodulator is converted to a digital value by way of an AID converter. The difference between the two is detected by error detection means and a control signal FCR to eliminate the difference is generated by frequency characteristic correction means in order to correct the frequency characteristic of a PLL or a pre-distortion filter.

The invention relates to an elliptic partial measurement device and a measurement method based on a spatial light modulator, which are applied to observation measurement on the thickness of a sample surface nano-scale thin film. The elliptic partial measurement device has the characteristics that the phase delay of polarization in the two vertical directions of a light beam is changed by adopting the spatial light modulator, an elliptic partial image of the sample surface thin film is recorded by adopting an area array detector, data is processed by adopting a fitting algorithm and an iterative algorithm, and the shape parameter of the sample surface thin film is accurately measured. The elliptic partial measurement device has the beneficial effects that no rotating part exists, the system instability and the azimuth angle deviation are eliminated, the elliptic partial measurement device is not sensitive to temperature, and the defects of a polarizer rotating type and photo-elastic modulation type ellipsometer are effectively overcome.

A voltage controlled oscillator 1, a variable frequency divider 2, a phase comparator 3, and a loop filter 4 form a Phase Locked Loop (PLL). A sigma-delta modulator 5 sigma-delta modulates data obtained by adding a fractional part M2 of the frequency division factor data with modulation data X by using an output signal of the variable frequency divider 2 as a clock. An output signal of the sigma-delta modulator 5 is added to an integral part M1 of the frequency division factor data, and the resultant data becomes effective frequency division factor data 13 of the variable frequency divider 2. An output signal of the sigma-delta modulator 5 also becomes control data 14 after passing through a D/A converter 6, a low-pass filter 7, and an amplitude adjustment circuit 8. The control data 14 is inputted into a frequency modulation terminal of the voltage controlled oscillator 1. Therefore, it is possible to provide a frequency modulator that can use a reference signal source having no frequency modulation function, and perform modulation over a wide range of frequencies based on a digital modulation signal.

The invention relates to a low polarization dependent loss lithium niobate straight-bar waveguide phase modulator and a manufacturing method of the low polarization dependent loss lithium niobate straight-bar waveguide phase modulator. The low polarization dependent loss lithium niobate straight-bar waveguide phase modulator comprises a lithium niobate optical waveguide chip, a first polarization-maintaining pigtail assembly and a second polarization-maintaining pigtail assembly, wherein the first polarization-maintaining pigtail assembly and the second polarization-maintaining pigtail assembly are bonded to the two ends of the lithium niobate optical waveguide chip in a coupling mode respectively, the lithium niobate optical waveguide chip comprises a lithium niobate substrate, a titanium diffusion waveguide area, annealing external diffusion areas and metal electrodes, an x-cut y-pass chip is adopted for the lithium niobate substrate, the titanium diffusion waveguide area and the annealing external diffusion areas are arranged on the surface layer of the lithium niobate substrate, the annealing external diffusion areas are arranged on the two sides of the titanium diffusion waveguide area respectively, the metal electrodes are arranged on the surfaces of the annealing external diffusion areas, the positive electrode and the negative electrode are symmetrical about the titanium diffusion waveguide area, and the first polarization-maintaining pigtail assembly and the second polarization-maintaining pigtail assembly respectively comprise a first polarization-maintaining optical fiber and a first optical fiber fixing block. The low polarization dependent loss lithium niobate straight-bar waveguide phase modulator achieves low insertion loss and low polarization dependent loss of a device at the same time, and achieves power even distribution of two polarization states, the situation of modulation waveform distortion is effectively eliminated, and accuracy of electro-optical modulation is improved.

First and second calibration signals (308, 309) are sent to a frequency divider (102) and an adder (116) of a PLL section (100A), demodulated in a demodulator (111), filtered through a low pass filter (113) and a high pass filter (114) and thereafter sent to a modulation signal control circuit (115). The modulation signal control circuit (115) generates control information (318) in comparison with the phase and amplitude of the first and second calibration signals (308 and 309) and sends the control information (318) to a modulation control signal generator (106). Modulation control signal generator (106) holds the control information (318) and controls the values of the first modulation signal and second modulation signal sent to the frequency divider (102) and adder (116) on the based on the control information (318) held in modulation operation.

The invention relates to an active terahertz optical comb tooth width modulation method. The method comprises the steps of outputting an electrical signal with a periodic change at a frequency f by means of a signal source to act on a step recovery diode, and outputting an electric pulse signal with the time domain interval being T= 1/f and the pulse width being in a picosecond order of the step time of the step recovery diode on the load; modulating an intensity modulator with the electric pulse signal, and outputting a laser pulse signal with the time domain interval same as that of the electric pulse signal and the pulse width similar to that of the electric pulse signal; then conducting pulse broadening, power amplification and pulse width compression on the laser pulse signal to obtain an ultra-short impulse sequence with the femtosecond pulse width and the evenly spaced time domain, taking the ultra-short impulse sequence as a repetition frequency accurate locking femtosecond laser light source to act on a terahertz generation device, and obtaining a repetition frequency accurate locking terahertz optical comb. According to the method, active adjustment of the terahertz comb tooth width is achieved through adjustment of an electrooptic modulator. The modulation accuracy of the terahertz comb tooth is high and the adjustable range is wide.

The invention discloses a liquid crystal aberration correcting method without wavefront detection. A used system comprises a liquid crystal aberration corrector, an image acquisition module, a convolutional neural network module and a grayscale conversion module. The specific method is as follows: the liquid crystal aberration corrector is used as an executing mechanism to correct distorted wavefront of received light; the image acquisition module is responsible for receiving light beams after liquid crystal correction, and acquiring the light beams as light spot images; after large-amount light spot data training, the convolutional neural network module is used for carrying out fitting according to the light spot images acquired by an imaging system to obtain Zernike coefficients corresponding to light spots; and finally, the grayscale conversion module is used for converting the Zernike coefficients obtained by fitting into grayscale values and controlling the liquid crystal aberration corrector to correct an aberration.

A mobile communication terminal device of the present invention includes: a voltage detector for detecting a battery voltage at the time of a voltage drop; a correction phase storage section for storing pieces of correction phase information each having a characteristic opposite to that of a phase error in a carrier wave produced due to a drop in the battery voltage; a correction phase outputting section for selecting correction phase information based on the battery voltage at the time of the voltage drop and outputting the selected correction phase information to a baseband modulator to change phase information in a baseband signal; and a modulator for modulating a carrier wave according to the baseband signal output from the correction phase outputting section so as to cancel the phase error included in the carrier wave.

The invention discloses a high-voltage end current detection circuit. The circuit comprises a mapping unit, a correction feedback unit, a modulation unit, an execution unit and a load, wherein the correction feedback unit comprises a resistance potential-divider network, a reference voltage unit, a subtraction unit, a first logarithm operation unit, a second logarithm operation unit, a current superposition unit, a voltage/current conversion unit and a summator. The current has the characteristics of high current detection accuracy, wide application range and low system cost.

The invention discloses a three-dimensional displacement measurement system and method based on laser self-mixing grating interference, and the system comprises a semiconductor laser sensor head, a plane reflector, a reflective two-dimensional plane grating, a data acquisition card and a computer, wherein the laser emitted from the semiconductor laser sensor head is incident on the reflective two-dimensional grating, the corresponding diffracted light is fed back to the semiconductor laser sensor head along the original optical path to generate self-mixing interference, the self-mixing interference signal is converted into an electrical signal by the photodetector built in the semiconductor laser and is output to the data acquisition card to obtain three-dimensional displacement of the target to be measured after computer processing. The invention solves the problem that the range of a traditional grating interferometer is limited when performing out-of-plane displacement measurement,is more compact than the traditional grating interferometer, maintains the advantages of self-collimation of the laser self-mixing interferometer, and can realize three-dimensional real-time displacement measurement system and method with a simple structure, wide rang and high resolution.

Disclosed is an unmanned aerial vehicle surveillance reconnaissance system. The unmanned aerial vehicle surveillance reconnaissance system is connected with a control terminal through wireless network and comprises a flight processor, a servo mechanism driving an unmanned aerial vehicle to fly according to instructions of the flight processor, a first communication subsystem, a camera subsystem and a first processor and is characterized in that when a personnel moving is shot in a monitored area through the camera subsystem, the first processor sends card finding information to non-contact equipment worn by the moving personnel through the communication subsystem and search replay information, the moving personnel is judged to be a legal personnel is the replay information is received, or else the moving personnel is judged to be a suspicious personnel, and the non-contact equipment receives electromagnetic wave sent by the communication subsystem and generates electric energy to supply internal circuit power to itself. By the arrangement, the personnel in the monitored area can be identified to be the legal personnel or not with no need of participation of a personnel in a ground control station.

The invention discloses a combination method of gamma components in three-level three-dimensional SVPWM (space vector pulse width modulation). According to the method, based on three-level three-dimensional SVPWM, a two-dimensional vector space is divided into an outer-layer zone, a middle-layer zone and an inner-layer zone from outside to inside; different vectors are selected according to the features of vector combination in each zone to combine gamma components; the action time of positive and negative small vectors is calculated through adopting a more accurate method, and the accuracy of the combination of the gamma components can be improved. The method has the advantages of clear processes, simplicity and convenience in implementation, high efficiency, large modulation range and high modulation precision. The combination method of the invention can be realized in a digital controller easily.

The invention relates to a light beam angle quick modulating device based on a digital micro-lens device, wherein the light beam angle quick modulating device belongs to the designing field of a photoelectric device and a calculating imaging system. The light beam angle quick modulating device comprises the components of the digital micro-lens device which performs spatial position area gating modulation on an incident light beam; a beam expanding system which performs collimating beam expanding on the light beam that is emitted from the micro-lens device; a lens array and an object lens system which realize conversion from light beam spatial area gating modulation to angle two-dimensional modulation through focus superposing; and a diaphragm which realizes spatial shearing to the parallellight beam and acquires parallel light that is propagated in different angles with a specific area dimension. Through the quick spatial modulation characteristic of the digital micro-lens device andthe light field angle information acquisition capability of the lens array, the light beam angle quick modulating device has advantages of realizing a quick adjusting function for the two-dimensionalangle of the spatial light beam, realizing no restriction by the resonant frequency of a mechanical device, and realizing spatial light beam angle modulation and coding.

A display control system, comprises: a spatial light modulator (SLM) constituted by a plurality of pixel elements placed in array; a first control unit for controlling each of the plurality of pixel elements under a state of ON or OFF; a second control unit for controlling each of the plurality of pixel elements under a state other than the ON or OFF states; a control changeover unit for dividing one frame period, for each pixel element of the plurality thereof, into a period of the first control unit controlling and that of the second control unit controlling, and also changing over between a control of the first control unit and that of the second control unit for each pixel element of the plurality thereof; and a data division unit for dividing input data to each of the plurality of pixel elements into first control unit-use data, which is input to the first control unit, and second control unit-use data which is input to the second control unit in accordance with the content of the present input data.