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2317 results about "Frequency mixing" patented technology
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Frequency mixing. The combination of two or more electromagnetic waves in a nonlinear medium to form another wave whose frequency is a sum or difference of the frequencies of the incident waves.
Plasma control using dual cathode frequency mixing
A method and apparatus for controlling characteristics of a plasma in a semiconductor substrate processing chamber using a dual frequency RF source is provided. The method comprises supplying a first RF signal to a first electrode disposed in a processing chamber, and supplying a second RF signal to the first electrode, wherein an interaction between the first and second RF signals is used to control at least one characteristic of a plasma formed in the processing chamber.
Owner:APPLIED MATERIALS INC
Laser system for generation of high-power sub-nanosecond pulses with controlable wavelengths in 2-15 mum region
ActiveUS20060153254A1Big spaceSubstantial temporal overlapLaser using scattering effectsSurgical instrument detailsSystems designHigh energy
A laser system capable of efficient production of high energy sub-nanosecond pulses in the 2-15 μm spectral region is disclosed. Diode pumped solid state lasers are used as pump sources. The system design is simple, reliable and compact allowing for easy integration. The laser system includes a combination of compact solid-state ˜1 micron laser sources, producing high power picosecond pulses, with optical parametric amplification and a quasi-continuous wave laser for seeding the amplification process that enables the efficient conversion of the high power ˜1 micron laser radiation to tuneable mid-infrared sub-ns pulses. New parametric processes are presented for achieving high gains in bulk nonlinear crystals. Furthermore, a method of exceeding the fundamental conversion efficiency limit of direct three wave mixing is presented. The compact and robust nature of this novel laser system opens up the use of high power and high peak power mid-infrared laser pulses to a wide variety of important medical and dental applications.
Owner:LIGHT MATTER INTERACTION
Techniques for detecting RFID tags in electronic article surveillance systems using frequency mixing
ActiveUS20060273902A1Co-operative working arrangementsNear-field systems using receiversMonitoring systemEnergy coupling
Disclosed are a system and method to detect RFID tags in electronic article surveillance systems using frequency mixing. The system includes an RFID module that includes an energy coupler to receive transmitted energy that includes a first signal at a first frequency and a second signal at a second frequency, and a mixing element to mix the first and second signals, to generate a third signal at a third frequency, and the energy coupler to transmit the third signal to an EAS detection system. Other embodiments are described and claimed.
Owner:SENSORMATIC ELECTRONICS CORP
Personnel detection and counting system based on millimeter wave radar
ActiveCN110118966AEasy to detectAchieve countRadio wave reradiation/reflectionDigital signal processingData set
The invention provides a personnel detection and counting system based on a millimeter wave radar, wherein the millimeter wave radar is installed at a set position of a monitoring area, the millimeterwave radar transmits millimeter wave band radio frequency signals to the monitoring area through a multi-transmitting and multi-receiving antenna of the millimeter wave radar and receives echo signals at the same time, the echo signals are subjected to frequency mixing with the transmitted signals and then subjected to down-conversion to obtain beat intermediate frequency signals, and the beat intermediate frequency signals are sampled to obtain an echo sampling sequence. A digital signal processor reads the echo sampling sequence and performs signal processing to obtain a detected point cloud data set. An ARM processor reads the point cloud data set, meanwhile, Kalman filtering tracking is carried out on the point cloud data, continuous observation of states and the number of a pluralityof human body moving targets is achieved, the positions and the number of people in the monitoring area are obtained, and the number of people in the monitoring area is counted. The personnel detection and counting system based on the millimeter wave radar can track at least 20 targets simultaneously, provide the position and speed information of the targets, effectively judge the state of the targets and give early warning in time.
Owner:长沙莫之比智能科技有限公司
Organic semiconductor diode
InactiveUS7211824B2Solid-state devicesSemiconductor/solid-state device manufacturingSchottky barrierP–n junction
The present invention relates to organic semiconductor diodes, in particular, to the diodes with nonlinear current-voltage characteristics, which are used for power switching, rectifying variable signals, and frequency mixing. The organic semiconductor diode with the p-n junction comprises an anode, cathode, a hole transport layer in contact with the anode, and an electron transport layer in contact with the cathode, and two transport layers being in contact with each other. Another aspect of the present invention is a Schottky barrier diode comprising anode, cathode, and an organic semiconductor layer, wherein the semiconductor layer is either hole or electron transport layer. At least one of the transport layers is characterized by a globally ordered crystalline structure with intermolecular spacing of 3.4±0.3 Å in the direction of one crystal axis. One more aspect of the present invention is a method for obtaining an organic semiconductor layer with the electron-hole type of conductivity.
Owner:NITTO DENKO CORP
Multi-mode multi-frequency global navigational satellite system receiver radio frequency front end device
ActiveCN103117767AEasy to changeEasy to adjustSatellite radio beaconingTransmissionLow noiseSignal processing circuits
The invention discloses a multi-mode multi-frequency global navigational satellite system receiver radio frequency front end device. The device comprises a low-noise amplifier, a power divider, and multiple radio-frequency signal processing circuits, wherein the low-noise amplifier, the power divider, and the multiple radio-frequency signal processing circuits are connected in sequence. Each radio-frequency signal processing circuit comprises a first radio-frequency switch, a radio-frequency filter bank, a second radio-frequency switch, a radio-frequency amplifying module, a lower frequency mixing module, an intermediate frequency filter module, an intermediate frequency amplifying module, and an automatic gain control unit, wherein the first radio-frequency switch, the radio-frequency filter bank, the second radio-frequency switch, the radio-frequency amplifying module, the lower frequency mixing device, the intermediate frequency filter module, the intermediate frequency amplifying module, and the automatic gain control unit are connected in sequence. The lower frequency mixing module comprises a lower frequency mixing device and a local oscillating generating module which are connected with each other. A control unit is connected with the first radio-frequency switch and the second radio-frequency switch of each radio-frequency signal processing circuit and the local oscillating generating module of the lower frequency mixing module. The device can flexibly select intermediate frequency inputting from various combination frequency ranges of a quad-mode 11 frequency range, and therefore functions of collecting in the same module and processing navigation system intermediate frequency signals of four system satellites are realized, namely a global position system (GPS), Glonass, Galileo, and Big Dipper.
Owner:WUHAN UNIV
Measuring device for electrical resistivity of electromagnetic waves while drilling and measuring method thereof
ActiveCN102704921AHigh precisionReduce operating frequencyElectric/magnetic detection for well-loggingConstructionsMeasurement devicePhase difference
The invention discloses a measuring method for electrical resistivity of electromagnetic waves while drilling, comprising the following steps: generating an electromagnetic wave power signal with specific frequency; emitting the electromagnetic wave power signal into a ground layer through an emitting antenna coil; receiving two electromagnetic wave power signals including measured ground layer information through two receiving antenna coils so as to generate two paths of electromagnetic wave power signals including the measured ground layer information; carrying out band-pass filtering to the two paths of the electromagnetic wave power signals including the measured ground layer information, and carrying out AD sampling to the two paths of the electromagnetic wave power signals including the measured ground information which is subjected to the band-pass filtering so as to generate two paths of electromagnetic sampling digital signals; carrying out frequency mixing transformation and low-pass filtering to the electromagnetic wave sampling digital signals so as to generate amplitude value information and phase information; generating amplitude value ratio and phase difference according to the amplitude value information and the phase information; and generating an electrical resistivity drawing board of the electromagnetic wave power sinals in a chart inversion method according to the amplitude value ratio and the phase difference. An embodiment of the invention also discloses a measuring device for the electrical resistivity of the electromagnetic waves while drilling.
Owner:BC P INC CHINA NAT PETROLEUM CORP +1
Laser architectures for coherent short-wavelength light generation
InactiveUS20050169326A1Increase power levelMaximize efficiencyLaser using scattering effectsLaser arrangementsPoynting vectorRare earth
Several methods are disclosed for the generation of coherent short-wavelength electromagnetic radiation through optical nonlinear frequency mixing means. The invention involves several stages of efficient nonlinear frequency conversion to shift the output of high-power infra-red fiber-lasers into the vacuum ultraviolet (VUV). The described laser source architecture is designed around non-critically phase-matched (NCPM) sum-frequency mixing (SFM) interactions in the nonlinear crystal CLBO. The NCPM interaction is an optimum condition for bulk frequency conversion of cw radiation because it allows tight focusing of the input laser radiation without Poynting vector walk-off, thereby increasing the non-linear drive significantly. The sub-200-nm output wave is generated from SFM of a long-wave IR laser field and a short-wave UV laser field. The long-wave laser beam may be derived directly from a rare-earth-doped fiber laser, whereas the short-wavelength UV beam is provided as the fourth frequency harmonic of a second rare-earth-doped fiber laser system.
Owner:JACOB JAMES JEFFREY +1
Intracavity frequency-tripled CW laser
InactiveUS20050078718A1High frequencyImprove efficiencyLaser optical resonator constructionExcitation process/apparatusNonlinear crystalsPhysics
A method of intracavity frequency conversion in a CW laser includes causing fundamental radiation to circulate in a laser resonator. The fundamental radiation makes a first pass through an optically nonlinear crystal where a fraction of the fundamental radiation generates second-harmonic radiation in a forward pass through the crystal. The residual fundamental radiation and the second-harmonic radiation are then sum-frequency mixed in forward and reverse passes through an optically nonlinear crystal such that a fraction of each is converted to third-harmonic radiation. The residual second-harmonic radiation and fundamental radiation from the sum-frequency mixing then make a reverse pass through the second-harmonic generating crystal where the second-harmonic radiation is converted back to fundamental radiation. The third harmonic radiation can be delivered from the resonator as output radiation, or can be used to pump another optically nonlinear crystal in an optical parametric oscillator. Second-harmonic radiation can also be used to pump an optical parametric oscillator.
Owner:COHERENT INC
Radio-frequency module, transceiver and method for switching control of transceiver
ActiveCN101572939AAdapt to various application scenariosPower managementSpatial transmit diversityHandoff controlTransceiver
The embodiment of the invention discloses a radio-frequency module, a transceiver and a method for switching control of the transceiver. The radio-frequency module comprises a first receiving amplification branch, a first receiving frequency mixer, a second receiving frequency mixer, a frequency mixing switching module and a control module, wherein the first receiving amplification branch is connected with the first receiving frequency mixer; the frequency of a local oscillation signal adopted by the first receiving frequency mixer is more than, less than or equal to that of a local oscillation signal adopted by the second receiving frequency mixer; and the control module is used for controlling the frequency mixing switching module to establish a connection between the first receiving amplification branch and the second frequency receiving mixer, or controlling the frequency mixing switching module to switch off the connection between the first receiving amplification branch and the second receiving frequency mixer. In the technical proposal provided by the embodiment of the invention, the radio-frequency module of the transceiver adopts an expandable framework, can expand the framework and switch working modes as required, and can adapt to various application scenes.
Owner:SHANGHAI HUAWEI TECH CO LTD
High dynamic satellite navigation signal rapid capture and tracking system and method
ActiveCN106855628AImprove capture efficiencyReduce lossesSatellite radio beaconingIntermediate frequencyDynamic models
The invention relates to a high dynamic satellite navigation signal rapid capture and tracking system and method. The method comprises the following implementation steps that S1, related parameters are set according to the capture requirements, and intermediate frequency signals are read to be mixed with local carrier; S2, windowing is performed on PMF and FFT modules based on the conventional PMF+FFT to implement capturing; S3, an adaptive threshold adjustment method is adopted on signal peak judgment after FFT operation so as to obtain the capture result; S4, the process enters the tracking stage, frequency mixing and pseudo code correlation are performed on the intermediate frequency data and the result after correlation is integrally cleared so as to obtain a coherent integral value; S5, dimension enlarged unscented Kalman filter is adopted for carrier tracking, and the state vector optimal estimation value is obtained according to the dynamic model and the measurement model of the system; and S6, the conventional code ring under carrier aiding is adopted in code tracking. According to the method, the problems of rapid capture and tracking of the high dynamic satellite navigation signals can be solved, and the dynamic performance can be 100g.
Owner:BEIJING MXTRONICS CORP +1
Low-interception speed measurement method and radar device
InactiveCN104076352ALow probability of interceptReduce probabilityRadio wave reradiation/reflectionFrequency spectrumEngineering
A low-interception speed measurement method comprises the steps that 1, frequency modulated continuous waves are generated, echo signals of an object with measured speed are received through an antenna, frequency mixing is carried out on the echo signals and B-path signals, and baseband signals are obtained; 2, the baseband signals are converted into digital signals, sampling and zero filling are carried out, FFT is carried out on the rising part of trace frequency, FFT is carried out on the reduction part of return trace frequency after conjugate taking, and frequency spectrums corresponding to positive / negative frequency modulation slopes are obtained; 3, the frequency spectrums corresponding to the positive / negative frequency modulation slopes are subtracted after module taking, the difference value is changed into an absolute value, and an objective frequency spectrum is obtained; 4, whether an object to be detected exists or not is determined, and if the object to be detected exists, the frequency corresponding to two peak value points within the frequency spectrum normalization range is found out in the objective frequency spectrum, and the speed of the object to be detected is worked out. The invention further discloses a low-interception speed measurement radar. The low-interception speed measurement method and radar have the advantage that the probability that the lower-measurement-speed radar is intercepted by a radar detector can be effectively reduced due to the adoption of the frequency modulated continuous waves with low-interception-probability wave forms.
Owner:UNIV OF ELECTRONICS SCI & TECH OF CHINA
Measuring brillouin backscatter from an optical fibre using a tracking signal
ActiveUS20100002226A1Narrow down the frequency rangeReduce the amount requiredReflectometers using simulated back-scatterConstructionsFrequency measurementsFrequency shift
A method for measuring Brillouin backscattering from an optical fibre (18), comprises frequency mixing a first signal with a frequency f B (t) representative of the Brillouin frequency shift in backscattered light received from a deployed optical fibre with a second signal at a frequency f i (t) that varies in time in the same manner as a Brillouin shift previously measured from the fibre to produce a difference signal with a difference frequency iF(t) that has a nominally constant value corresponding to the situation where the received light has a Brillouin shift that matches the previously measured shift. The difference signal is acquired and processed to determine properties of the Brillouin shift and corresponding physical parameters producing the shift. The frequency mixing can be carried out. optically or electrically. Techniques for acquisition of the difference signal include the use of parallel frequency measurement channels and fast rate digital sampling.
Owner:SCHLUMBERGER TECH CORP
Wireless terminal transceiver of 60GHz RoF (Radio over Fiber) access system
ActiveCN102664684AImprove modulation effectLow costDc level restoring means or bias distort correctionRadio-over-fibreDigital signal processingTransceiver
The invention discloses a wireless terminal transceiver of a 60GHz RoF (Radio over Fiber) access system. Secondary subharmonic frequency mixing is adopted, and the frequency of a needed local oscillation signal is reduced in a frequency multiplication frequency mixing way, so that the problem of leakage of the local oscillation signal to an antenna, i.e., a radiofrequency transmitting end in the conventional wireless terminal transceiver scheme is solved, and the circuit modulation performance is improved. Meanwhile, a downlink medium frequency analog signal obtained after secondary subharmonic down-conversion is subjected to downlink medium frequency digital signal processing after ADC (Analog to Digital Conversion) to obtain a needed downlink digital baseband signal; and an uplink digital baseband signal is subjected to uplink medium frequency digital signal processing to obtain an uplink medium frequency digital signal. A series of medium frequency digital signal processing such as odd-even extraction or interpolation, symbol modulation, delay filtering, demodulation or modulation and the like is performed in a digital domain, so that the problem of IQ orthogonal mismatch caused by 90-degree phase change on a local oscillation signal for obtaining two paths of analog signals in an analog frequency domain of the conventional receiver is solved.
Owner:UNIV OF ELECTRONICS SCI & TECH OF CHINA
Fully-digital direct sequence spread spectrum communication system and rapid pseudo code capturing method thereof
ActiveCN102571137ASimple designReduce power consumptionTransmissionDigital signal processingFpga implementations
The invention discloses a fully-digital direct sequence spread spectrum communication system and a rapid pseudo code capturing method thereof. A digital signal is processed by using an FPGA (Field Programmable Gate Array) which comprises a pseudo code capturing module, a sampling signal of an ADC (Analog To Digital Converter) is subjected to frequency mixing with a signal of a local carrier NCO (Numerically Controlled Oscillator) and filtered to obtain a baseband signal, residual carrier Doppler frequency is eliminated from the baseband signal by adopting a differential multiplying mode, thus the phase deviation of a receiving signal and a local pseudo code is further obtained through an FFT (Fast Fourier Transform) algorithm without scanning on a carrier frequency domain; and when the phase deviation of the pseudo code is obtained, a local pseudo code phase is modified and is subjected to correlation degree of dissociation with the receiving signal, and the carrier Doppler frequency is figured out by using the FFT algorithm, and is compensated to a carrier NCO and a pseudo code NCO, thus carrier frequency capturing and pseudo code capturing are realized.
Owner:ZHEJIANG UNIV
Transconductance-enhancing passive frequency mixer
InactiveCN102412786AImprove linearityReduce power consumptionActive element networkMulti-frequency-changing modulation transferenceFrequency mixerHemt circuits
Owner:SOUTHEAST UNIV WUXI CAMPUS
Circuit and method for receiving and mixing radio frequencies in a direct conversion receiver
InactiveUS20060293017A1Improve linearityQuality improvementModulation transference balanced arrangementsTransmissionHarmonicFrequency mixer
A frequency mixing circuit and a frequency mixing method. The frequency mixing circuit includes first and second differential amplifiers, a subtracter and a mixer. The first differential amplifier amplifies a first pair of input signals having a first frequency to generate a first differential signal. The second differential amplifier amplifies a second pair of input signals having the first frequency orthogonal to the first pair input signals to generate a second differential signal. The subtracter subtracts the second differential signal from the first differential signal. The mixer mixes the subtracted signal with a first and second pairs of drive signals having a second frequency orthogonal to each other, in a sub-harmonic double balanced mixing mode, so that the mixer generates a pair of output signals orthogonal to each other without secondary harmonics.
Owner:KIM YOUNG JIN +1
Coherent terahertz radiation source
ActiveUS7515801B2High power outputLow THz lossLaser detailsCladded optical fibreElectricityRoom temperature
A THz radiation source comprising a dual waveguide heterostructure is provided. The dual waveguide heterostructure includes an optical waveguide contained within a larger THz waveguide layered structure. The radiation source provides a coherent guided wave of THz radiation which is generated via difference frequency mixing in a gain medium with a large second-order nonlinearity and propagated with low THz loss by a dielectric medium in the layered waveguide structure. The THz radiation source is compact, has a high power output, and may be operated in continuous-wave (CW) mode at room temperature.
Owner:WISCONSIN ALUMNI RES FOUND
Pulse laser coherent wind measuring radar
InactiveCN103823221AImprove signal-to-noise ratioSimple structureElectromagnetic wave reradiationICT adaptationFiberOptoelectronics
The invention brings forward a pulse laser coherent wind measuring radar, for the purpose of providing a pulse laser coherent wind measuring radar which has the advantages of high measuring precision, simple structure and convenient installation and debugging. The pulse laser coherent wind measuring radar is realized through the following technical scheme: a fiber pulse laser emission system is taken as an emission source for generating two beams of laser, one beam of high repetition frequency pulse sequence laser for wind field detection is directly coupled through an optical circulator and enters an optical transmit-receive scanning system to perform collimated emission towards a target spatial domain, the optical circulator utilizes a polarization splitting characteristic to carry out isolation splitting on emission light and air aerosol scattering echo wave light, the air aerosol scattering echo wave light is selected to enter a fiber combiner, the other beam of laser, generated by the fiber pulse laser emission system, is taken as local oscillator light for inputting into a balance amplification photoelectric detector together with the echo wave light in a frequency mixing mode for optical amplification of a frequency mixing signal, through acquisition processing of a signal acquisition processor, the radial speed of each range gate in a current laser emission direction is calculated, and the radial speeds are transmitted to a radar operation display interface.
Owner:SOUTH WEST INST OF TECHN PHYSICS
Digital intermediate frequency conversion method and system used in repeater
ActiveCN101197606AHigh degree of integrationReduce usageFrequency-modulated carrier systemsRadio relay systemsProgrammable logic deviceUp conversion
The invention discloses a frequency changing method of digital middle-frequency signals used in a repeater station system, which comprises two steps of an up frequency changing process and a down frequency changing process: in the down frequency changing process, the middle-frequency signals after digital analog conversion are processed by digital wave filtering processes such as an extraction process, a bandpass compensation, a signal shaping process, etc. after a digital frequency mixing process, the middle-frequency signals can be moved to a zero middle-frequency, a digital signal with the high speed rate can extracted as two-channel quadrature digital baseband I, Q signal with a low speed rate; in the up frequency changing process, the digital baseband I, Q signals acquired from the down frequency changing process are processed by an interpolation filtering process, then processed by I, Q modulation process and a secondary frequency mixing process, and the signals can be processed by a gain adjustment and control, finally high speed digital middle-frequency signals are outputted. Correspondingly, the invention also discloses a frequency changing system thereof. The invention can be achieved by using PLC units such as FPGA, CPLD, EPLD and DSP, etc., which can improve the integration degree of repeater station equipment; meanwhile, an ASIC chip is removed to decrease heating capacity and to improve the reliability.
Owner:COMBA TELECOM SYST CHINA LTD
Delay-locked-loop-based remote microwave signal phase-stabilized optical fiber transmission device
InactiveCN102215104ALow signal to noise ratioAvoid disadvantages such as phase polarity ambiguityFibre transmissionSynchronising arrangementPhase differenceDelay-locked loop
The invention discloses a delay-locked-loop-based remote microwave signal phase-stabilized optical fiber transmission device, which realizes the phase synchronization of a local microwave signal and a remote microwave signal by utilizing a delay-locked loop. The device realizes optoelectronic heterodyne mixing by utilizing the nonlinear effects of an optoelectronic modulator for phase detection, drives and controls a microwave delayer by feeding a phase difference signal back, performs phase change on the microwave signals, compensates microwave signal phase disturbance caused by the delay change of a transmission link, keeps a phase synchronism relationship between the local microwave signal and the remote microwave signal, solves the problem of phase asynchronism between the local microwave signal and the remote microwave signal, fulfills the aim of phase-stabilized transmission of the microwave signals, adopts noncoherent correction, and has the advantages of wide dynamic range, high stability and the like, besides a long phase-stabilized transmission distance.
Owner:SHANGHAI JIAO TONG UNIV
Compressive-sensing-based sparse signal under-sampling method and implementation device
ActiveCN103178853ADownsamplingReduced rate requirementsAnalogue-digital convertersLow-pass filterSignal on
The invention relates to a compressive-sensing-based sparse signal under-sampling method and an implementation device, which are used for lowering a sampling rate of frequency-domain sparse signals on the premise of guaranteeing the restoration effect of the signals. The method comprises the following steps of: generating a trigger signal and an m sequence by an FPGA (Field Programmable Gate Array), carrying out frequency mixing on the m sequence and the measured sparse signal after the m sequence is modulated, and carrying out filtering by a low pass filter; sampling the filtered signal and storing sampled data by a data sampling module after the data sampling module detects the triggering signal; and calculating a transfer function of a system and the m sequence corresponding to the sampled data when the signal is reconstructed, and then restoring the original signal by an OMP (Orthogonal Matching Pursuit) signal reconstructing algorithm. The compressive-sensing-based sparse signal under-sampling method and the implement device are suitable for the under-sampling of frequency-domain sparse analogue signals.
Owner:HARBIN INST OF TECH
Doppler radar-based non-contact type vibration measuring method
ActiveCN106644030AReduce power consumptionCompact structureSubsonic/sonic/ultrasonic wave measurementUsing wave/particle radiation meansVibration amplitudeData acquisition
The invention discloses a Doppler radar-based non-contact type vibration measuring method. The method includes the following steps: S1. directly facing a measured vibration object to emit single-frequency microwaves in the form of continuous waves, and receiving radar echoes after modulation by vibration motion; S2. performing amplifying, filtering and quadrature mixing on echo signals and taking down conversion signals to obtain two paths of baseband signals I(t) and Q(t); S3. performing data collection on the baseband signals to obtain discrete digital signals; and S4. performing phase demodulation processing on the discrete baseband signal I[n] and Q[n], and extracting vibration amplitude and frequency information. The Doppler radar-based non-contact type vibration measuring method provided by the invention uses a microwave radar to perform non-contact type vibration measurement based on a Doppler effect, has good low frequency measurement sensitivity, is high in environmental adaptation, and can perform accurate vibration measurement under the condition of containing a barrier. The microwave radar used by the method is compact in structure and low in cost and has relatively low power consumption, thereby providing a solution to integration of a large-scale vibration measuring system.
Owner:SHANGHAI JIAO TONG UNIV
Monolithic microchip laser with intracavity beam combining and sum frequency or difference frequency mixing
ActiveUS20060209912A1Avoid polarizationLasing suppressionOptical resonator shape and constructionActive medium shape and constructionLow noiseNonlinear optical crystal
A method for producing low-noise laser output at various wavelengths and / or in various operation modes in a monolithic microchip laser comprises schemes of generating two fundamental beams in separate cavities, precise intracavity beam combination based on the walk-off effect in birefringent crystal, and wavelength conversion in nonlinear optical crystals. The fundamental beams are produced from light sources selected upon the desired wavelengths, polarizations, and other features related to the laser output. Low-noise laser devices operated in SLM or with spectra of flat-top or desired bandwidths are constructed according to the method. High-volume fabrication is feasible. Apparatus of compact size and efficient frequency conversion is demonstrated with various configurations including those for generating low-noise 491 nm laser, as a replacement of Argon ion laser.
Owner:PAVILION INTEGRATION
Film system structure for enhancing Terahertz radiation absorption rate and preparation method thereof
ActiveCN102529211AImprove surface to body ratioIncreased radiation absorptionRadiation pyrometryMetal layered productsSilicon oxideReactive-ion etching
The invention discloses a film system structure for enhancing Terahertz radiation absorption rate and a preparation method of the film system structure, wherein the film system structure is located at the top layer of a sensitive unit of a Terahertz detector and comprises a dielectric thin film and a Terahertz absorption layer located on the dielectric thin film; the dielectric thin film is a low-stress silicon nitride or silicon oxide thin film prepared by PECVD (Plasma Enhanced Chemical Vapor Deposition) frequency-mixing technology and etched into a micro nanometer-level rough surface by reactive ions; and the Terahertz absorption layer is prepared on the rough-surface dielectric thin film via a magnetic control sputtering method. As surface-to-volume ratio of the Terahertz absorption layer is increased by the rough surface structure of the dielectric thin film, the Terahertz radiation absorption rate is effectively enhanced; and the preparation process is simple and reasonable, and large-area preparation and integration are easy to carry out, so that the film system structure can be widely applied to the field of various Terahertz detecting and imaging technologies and strong support is provided to the development of high-performance Terahertz detectors.
Owner:UNIV OF ELECTRONIC SCI & TECH OF CHINA
Automobile active anti-collision radar based on pseudorandom code and linear frequency modulated continuous wave
InactiveCN102162848AEnhanced inhibitory effectRemove inhibitionRadio wave reradiation/reflectionLow noiseControl signal
The invention relates to an automobile active anti-collision radar based on pseudorandom code and linear frequency modulated continuous wave, belonging to the field of automobile radar, comprising a pseudorandom code and linear frequency modulated control signal generator, a pseudorandom code and linear frequency modulated continuous wave emitter, a sending antenna, a receiving antenna, a low-noise amplification mixed frequency receiving channel, a linear frequency modulated signal processing and pseudorandom code multi-path parallel correlation processor, a parallel data processor and an executing terminal. The pseudorandom code is used for modulating the phase of radar carrier wave and performing linear frequency modulation to the radar carrier wave so as to form a double-modulation emitting signal. Two systems are combined, so that the inhibition ability of interference echo is improved; the false alarm caused by false targets is removed; different codes of different automobile radars are achieved; the interference caused by the automobile radar is removed; the detection ability of the active anti-collision radar is improved; the false alarm rate is improved; and the inhibitionability under complex road condition is good.
Owner:BEIJING INSTITUTE OF TECHNOLOGYGY +1
Single-substrate integrated terahertz front end
ActiveCN104362421AReduce the numberReduce processingCoupling devicesIntermediate frequencyBand-pass filter
The invention discloses a single-substrate integrated terahertz front end. The single-substrate integrated terahertz front end comprises a dielectric substrate, an inputting waveguide micro-strip transition and a micro-strip air cavity; the micro-strip air cavity is the air cavity; the inputting wave micro-strip transition (a standard waveguide opening WR-15), a CMRC (compact microstrip resonant cell) structure micro-strip low-pass filter, a parallel double-frequency-doubling diode, a frequency-doubling matching branch knot, a local oscillator band-pass filtering device, a frequency-mixing matching branch knot, a frequency-mixing diode, a radiofrequency waveguide micro-strip transition (a standard waveguide WR-2.2) and an intermediate-frequency low-pass filtering device are sequentially arranged on the single-substrate integrated terahertz front end from left to right. The number of dielectric substrates is reduced; circuits are integrated on the substrate; the number of machined cavities is also reduced; the single-substrate integrated terahertz front end is easy to machine and assemble; designing and machining on the waveguide transition are reduced; and the size of the cavity is also reduced.
Owner:UNIV OF ELECTRONICS SCI & TECH OF CHINA
All-optical high bandwidth sampling device based on a third-order optical nonlinearity
An all-optical sampling device using four-wave mixing in third-order optically nonlinear materials is described. The four-wave mixing based sampler comprises a waveguide combiner, which adds a gate optical signal to a signal of interest to be sampled. In a four-wave mixing region, a sampled signal at the output optical frequency is produced. All of the optical signals are sent to a passive optical filter, which preferentially discards the gate and signal optical frequencies, but preserves the sampled signal at the output optical frequency. The sampled signal at the output optical frequency can be observed, displayed, recorded or otherwise manipulated.
Owner:UNIV OF WASHINGTON CENT FOR COMMERICIALIZATION
High/intermediate-frequency front-end circuit of digital short-wave receiver
The invention relates to a high / intermediate-frequency front-end circuit of a digital short-wave receiver, which mainly comprises a PIN diode electric control attenuator, digital control electric tuning preselected tracking filter groups, a gain control low-noise amplifier, a direct digital frequency synthesizer, a plurality of frequency mixers, an intermediate-frequency amplifier, an amplitude detection and grain control circuit and a preselected controller, wherein a weak signal sensed by an antenna is subjected to tracking frequency selection by the first digital control electric tuning preselected tracking filter group after passing through the PIN diode electric control attenuator and then is subjected to frequency selection by the second digital control electric tuning preselected tracking filter group after being amplified by the gain control low-noise amplifier, the signal after being subjected to frequency selection is subjected to frequency mixing three times with the plurality of frequency mixers by three local oscillators formed by the frequency synthesizer and is transmitted to a demodulator for demodulation after being subjected to multistep intermediate-frequency amplification and gain control processing. The high / intermediate-frequency front-end circuit of the digital short-wave receiver can meet the requirement of high sensitivity, strong anti-interference performance and wide dynamic range for the short-wave receiver, is suitable for a frequency-hopping receiving machine with rapid frequency change and has the effects of low insertion loss, low in-band ripple and high selectivity.
Owner:WUHAN UNIV OF TECH
Turbine rotor blade accelerated life test load design method taking regard of flight damage
PendingCN107247002ADamage reasonably characterizedLife assessmentMaterial strength using tensile/compressive forcesDesign optimisation/simulationFatigue damageAviation
The invention relates to a turbine rotor blade accelerated life test load design method taking regard of flight damage. The method includes: 1) conducting frequency mixing treatment and rain flow counting on aeroengine flight missions and training subjects to acquire the frequency and time of each rotation speed cycle in actual flight, thus obtaining the load basic data of an engine within certain flight hours; 2) acquiring the temperature field and stress strain distribution of the blade under all states by finite element method, analyzing the blade static strength and endurance, and determining a lifetime testing part of the blade; 3) calculating the fatigue damage and creep damage of the blade testing part under a true flight load to acquire a ratio of creep damage and fatigue damage during rise and fall of a flight; and 4) designing a accelerated life test load spectrum of a full-size blade, and determining a conversion coefficient of the blade test load spectrum relative to out-field flight. The method provided by the invention can be used for acquiring the technical life of the blade and studying the remaining life of the blade, and saves time and economic cost for the fatigue-creep lifetime test of the blade.
Owner:BEIHANG UNIV
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