451 results about "Reference wave" patented technology

A microscope is disclosed which determines a complex three-dimensional representation of an object based on a series of recordings of the light wave diffracted by the object, wherein the direction of the wave lighting of the object varies between two succesive recordings. The diffracted wave interferes with a reference wave on a receiving surface and a frequency representation of the diffracted wave is computed from interference patterns received on the receiving surface. A plurality of frequency representations of diffracted waves are then superimposed yielding a frequency representation of the object. The phase of each frequency representation of a diffracted wave is shifted in order to compensate for variations of the phase difference between the reference wave and the wave lighting of the object.

A method of determining the analyte concentration of a test sample is described. A temperature gradient is introduced in the test sample and infrared radiation detectors measure radiation at selected analyte absorbance peak and reference wavelengths. Reference and analytical signals are detected. In the presence of the selected analyte, parameter differences between reference and analytical signals are detectable. These parameter differences, having a relationship to analyte concentration, are measured, correlated, and processed to determine analyte concentration in the test sample. Accuracy is enhanced by inducing a periodically modulated temperature gradient in the test sample. The analytical and reference signals may be measured continuously and the parameter difference integrated over the measurement period to determine analyte concentration.

A double reference wave modulation scheme for filterless power amplifiers is disclosed for reducing EMI and common mode voltages. In the filterless power amplifier, differential outputs for driving load impedance are feedback and corrected based on input audio signals. Reference wave generators generate reference waves. A control logic results pulses in the pair of differential outputs in response to a clock signal or a reference voltage and a cross relationship between the input audio signal and the first and second reference waves. Pulses of one of the differential outputs are not overlapped with pulses of the other of the differential outputs for eliminating common mode noises of the power amplifier.

A machine for generating piece-wise non-linear reference waveforms at low cost, particularly in integrated circuit technologies. The reference waveform can be a distorted sinusoidal waveform such as a truncated sinusoid. Provided that local distortion is low enough in some waveform segments, for instance, in the transitions between saturation levels, parts of the waveform can be used as non-linear reference segments in data converters based on comparison of inputs. The distorted sinusoidal waveform can also be filtered to reduce distortion. In the preferred embodiment of the invention, suitable sinusoids with high or low distortion can be generated using an op-amp configured with a Wien Bridge providing positive feedback and a resistor bridge providing negative feedback. The invention differs from prior art Wien Bridge oscillators in having negative feedback gain that forces the op-amp output into saturation. One filter stage is provided by the positive feedback network itself. Additional filtering can allow further distortion reduction. The specification suggests a cascade of servo-grounded Wien Bridge stages as a simple and efficient approach to the filtering. The invention can be fabricated using a small number of parts which are easy to fabricate with existing integrated circuit technologies such as CMOS, so that low-cost, low-power implementations can be included in mixed-signal chips as parts of A / D converters, D / A converters, or calibration signal generators. The invention is also amenable to massively parallel and shared implementations, for instance, on a CMOS image sensor array chip or on a image display device.

A method for irradiating a medium includes irradiating the medium with an electromagnetic wave which is scattered in the medium and modulated in frequency at a position in the medium; obtaining information corresponding to an interference pattern generated by interference between the modulated electromagnetic wave and a reference wave; and generating a phase conjugate wave, based on the obtained information, which irradiates the medium.

Apparatus for splitting, imaging, and measuring wavefronts with a reference wavefront and an object wavefront. A wavefront-combining element receives and combines into a combined wavefront an object wavefront from an object and a reference wavefront. A wavefront-splitting element splits the combined wavefront into a plurality of sub-wavefronts in such a way that each of the sub-wavefronts is substantially contiguous with at least one other sub-wavefront. The wavefront-splitting element may shift the relative phase between the reference wavefront and the object wavefront of the sub-wavefronts to yield a respective plurality of phase-shifted sub-wavefronts. The wavefront-splitting element may then interfering the reference and object wavefronts of the phase-shifted sub-wavefronts to yield a respective plurality of phase-shifted interferograms. An imaging element receives and images the phase-shifted interferograms. A computer connected to the imaging element measures various parameters of the objects based on the phase-shifted interferograms. Examples of measurements include flow parameters such as the concentrations of selected gaseous species, temperature distributions, particle and droplet distributions, density, and so on. In addition to flow parameters, the displacement (e.g., the vibration) and the profile of an object may be measured.

The invention provides a remote sensed estimating method of the large area planting area and the output, which establishes a spectrum which has the same growing stage and is correspondent with the field crown layer at the base of doing normal radiation and atmosphere adjustment to the remote sensed image, and computes the distance threshold value of the spectrum and compares the distance threshold value with the image initial wave spectrum and the reference wave spectrum to obtain TM plant unit, it then statistics the quantity of the TM plant unit from each image unit of middle resolution ratio imaging spectrum data MODIS with the same period and region to ascertain the planting number of the MODIS image, it then ascertains the planting area of the MODIS image according to each image unit area of the planting number and the MODIS.

The present invention discloses a fiber Bragg grating sensor system. The system according to the present invention comprises a wavelength tunable laser; a coupler for splitting output light from the wavelength tunable laser into two directions; a reference wavelength generating unit for receiving one directional output light from the coupler and for generating reference wave-lengths and an absolute reference wavelength in order to measure real-time wavelengths of the wavelength tunable laser; a fiber Bragg grating array for receiving the other directional output light from the coupler and for reflecting lights at each of the wave-lengths of the grating therein; a fiber grating wavelength sensing unit for measuring the time when each of the reflected lights from the fiber Bragg grating array is detected; a signal processing unit for figuring wavelength variation information with the use of the measured signals from the reference wavelength generating unit and for obtaining each of wavelengths of the detected lights from the fiber grating wavelength sensing unit; and a laser wavelength control feedback unit for applying AC voltage and DC voltage to the wavelength tunable filter in the wavelength tunable laser. Also, polarization dependency in the sensor system can be removed further installing a depolarizer or a polarization scrambler at the output end of the wavelength tunable laser. By applying the present invention, measurement accuracy of the grating sensor system 20 can be improved due to enhanced wavelength stability and suppression of polarization dependency. Therefore, the fiber Bragg grating sensor system based on the present invention would replace conventional structure / construction diagnosis systems.

The present invention relates to a switch controller, a power supply including the same, and a method for driving the same. An AC input of the power supply is connected to a rectification circuit. The power supply includes a power switch to which an input current passed through the rectification circuit flows during an on-period and a switch controller, the switch controller detects a half-on time point that is the intermediate time point of the on-period, detects a sense voltage that is determined by a current flowing to the power switch during the on-period at the half-on time point, generates a modulation wave by controlling a reference wave according to the detected voltage, and controls switching operation of the power switch according to the modulation wave.

A tunable optical filter for simulating the waveband spectrums of selected substances. The filter includes an optical waveguide with a core material for transmitting light energy and a nominal core refractive index for the core material. Predetermined periodic variations are formed in the core material of the optical waveguide between the input and output ends that alter the core refractive index of the waveguide at the location of the periodic variations. Depending upon the periodic variations, the waveguide produces a predetermined reference waveband spectrum output that matches the waveband spectrum of a selected substance. A modulator is coupled to the waveguide to selectively modulate the periodic variations to intermittently shift the reference waveband spectrum output to fine tune the filter and reduce signal noise. The filter is useful as a reference cell for correlation spectroscopy, DIAL LIDAR, equipment calibration, and other uses where a predetermined or known waveband spectrum is useful or desirable.

The invention relates to an on-line detection method for detecting the wave aberration of a projection objective of a photoetching machine. The on-line detection, revising, and controlling are done to the wave aberration of the projection objective by integrating an interferometer device on the photoetching machine. The interferometer device is a point-diffraction interferometer or a slit-diffraction interferometer and is provided with two measuring modules: a PSI measuring module and an FTM measuring module. The PSI measuring module adopts phase shifting interferometry with high measuring precision and is mainly used to detect the error calibration in an interferometer device system; the FIM measuring module adopts fourier transform method to treat with interference fringes with high measuring speed, and is mainly used to on-line detect and control the wave aberration of the projection objective. The method improves the measuring precision without reducing the measuring speed, and improves the measuring precision and reproducibility of the interferometer device by adopting a higher quality spherical reference wave to calibrate the systematic error caused by each component of the interferometer device without reducing the contrast ratio of the interference fringes.

The invention relates to a limit bit feedback and multiuser dispatching algorithm which comprises the following steps of: at the base station side, determining a loaded wave beam set for each subcarrier; at the user equipment side, obtaining the wave beam set information, forming an associated subcarrier on the basis of each subcarrier, calculating a channel quality estimation parameter of each wave beam, and determining the optimal wave beam and a key subcarrier; and if the channel quality corresponding to the optimal wave beam on the key subcarrier exceeds a scheduled threshold value, feeding a sequence number of the key subcarrier and the best wave beam number back to the base station side; and at the base station side, receiving the feedback information of the user equipment, expanding the feedback information of the key subcarrier to the associated subcarrier, determining a reference wave beam set adopted by the associated subcarrier on the basis of each subcarrier, and than carrying out the user dispatching on each wave beam, and finally carrying out the data transmission according to the selecting condition of the reference wave beam set and a user dispatching result. The invention has the advantages of less user feedback information amount, high feedback efficiency, large frequency spectrum multiplexing coefficient and high flexibility, simple realization, less signaling interaction between a user and a base station, and the like.

The invention discloses a fringe contrast ratio-adjustable large-numerical value bore diameter point-diffraction interference device and a fringe contrast ratio-adjustable large-numerical value bore diameter point-diffraction interference method. A linear polarization laser generates a parallel light through a 1 / 2 wave plate, a first 1 / 4 wave plate and a collimating and beam expanding system, the parallel light is focused on an interference pinhole of a point-diffraction plate through a microobjective, a detection wave front W1 is focused at an O point after passing through a second 1 / 4 wave plate to obtain a spherical wave front W1', a reflected light wave reflected by a spherical surface to be detected passes through the second 1 / 4 wave plate again to obtain a circularly polarized light of which the rotation direction is opposite to a reference wave front W2, and is reflected through a metal reflecting film on the point-diffraction plate, the detection wave front W1 and the reference wave front W2 are converged to change into a plane wave through a collimating lens, an interference fringe is obtained on a detector through a third 1 / 4 wave plate, a polarization analyzer and an imaging lens, and the detector timely acquires a corresponding interference pattern. The device and method simplify the point-diffraction interference adjusting difficulty, and provide a feasible method for the high-precision detection of a large-numerical value bore diameter spherical surface, particularly of a low-reflectivity spherical surface.

A double reference wave modulation scheme for filterless power amplifiers is disclosed for reducing EMI. In the filterless power amplifier, differential outputs for driving load impedance are corrected based on input audio signals by the error amplifier. Reference wave generators generate reference waves. Comparators are responsive to the reference waves and the input audio signal. Operation states of the switching unit are decided based on output signals of the comparators and the switching unit output the differential output. Besides, a feedback unit feeds the differential output back to the error amplifier. By this configuration, complex control logic is not needed.

A synchronous vector measuring device can measure an absolute phase angle of a synchronous vector excellent in continuous numerical stability at high speed and with high accuracy in a noisy electric power system. A voltage measuring part measures the voltage of the electric power system at a period equal to 1 / 4N (N being a positive integer) of one period of a reference wave. A voltage root-mean-square value calculation part calculates, at each voltage measuring timing, a voltage root-mean-square value at a specific timing from the voltages measured at past 4N timings including the specific timing. An absolute phase angle calculation part makes, at each voltage measuring timing, an inverse cosine of a value obtained by dividing the voltage measured at the specific timing by the product of the voltage root-mean-square value and the square root of 2, as the absolute phase angle of the synchronous vector at the specific timing.

A lightwave interference measurement apparatus includes a wavelength-variable laser which periodically performs wavelength scanning between first and second reference wavelengths to emit light beam, a wavelength-fixed laser which emits light beam having a third reference wavelength, a light beam splitting element which splits the light beams into reference light beam and light beam under test, a phase detector which detects a phase based on an interference signal of the reference light beam and the light beam under test, and an analyzer which sequentially determines an interference order of the third reference wavelength based on the third reference wavelength, first and second synthetic wavelengths, an integer component of a phase change amount in the wavelength scanning, and interference orders of the first and second synthetic wavelengths, and calculates an absolute distance between the surface under test and the reference surface.

A method for irradiating a medium includes irradiating the medium with an electromagnetic wave which is scattered in the medium and modulated in frequency at a position in the medium; obtaining information corresponding to an interference pattern generated by interference between the modulated electromagnetic wave and a reference wave; and generating a phase conjugate wave, based on the obtained information, which irradiates the medium.

Narrow virtual transmit pulses are synthesized by differencing long-duration, staggered pulse repetition interval (PRI) transmit pulses. PRI is staggered at an intermediate frequency IF. Echoes from virtual pulses form IF-modulated interference patterns with a reference wave. Samples of interference patterns are IF-filtered to produce high spatial resolution holographic data. PRI stagger can be very small, e.g., 1-ns, to produce a 1-ns virtual pulse from very long, staggered transmit pulses. Occupied Bandwidth (OBW) can be less than 10 MHz due to long RF pulses needed for holography, while spatial resolution can be very high, corresponding to ultra-wideband (UWB) operation, due to short virtual pulses. X-Y antenna scanning can produce range-gated surface holograms from quadrature data. Multiple range gates can produce stacked-in-range holograms. Motion and vibration can be detected by changes in interference patterns within a range-gated zone.

A magnetic resonance imaging apparatus includes a data acquisition unit and an image generating unit. The data acquisition unit sets a delay time from a reference wave based on heart rate information or peripheral pulse wave information previously acquired from an object and acquires MR signals by an imaging scan with the set delay time in synchronized with a beat. The delay time represents a time phase of a data acquisition timing in imaging in synchronized with the beat. The image generating unit generates a blood flow image based on the magnetic resonance signals.

An self adaptive optics system for based self-reference wave front sensor and continuous surface deformation lens is consisted of a wave front corrector, a Mach-Zehnder interference method-based self-reference wave front sensor and an industrial control computer. After through the wave front corrector, the beam is reflected into the Mach-Zehnder interference method-based self-reference wave front sensor. The wave front information detected by the Mach-Zehnder interference method-based self-reference wave front sensor passes the once matrix operation of the industrial control computer, then directly output the controlling voltage to the wave front corrector for closed loop. The wave front corrector using the independent unit continuous interference deformation lens has a quicker respond speed. The wave front detector using the interference principle has upper spatial resolution and detecting precision. Thereby, the wave front correction performance of the interference wave front detector-based self adaptive optics system is largely improved, the application domain of the self adaptive optics system is enlarged, and the advantages are obviously.

A system and method for irradiating a medium including irradiating the medium with an electromagnetic wave which is scattered in the medium and modulated in frequency at a position in the medium; obtaining information corresponding to an interference pattern generated by interference between the modulated electromagnetic wave and a reference wave; and generating a phase conjugate wave, based on the obtained information, which irradiates the medium.

Disclosed herein are a user scheduling and beamformer design method, apparatus, and storage medium for multi-user MIMO downlink based on two-stage beamforming or single-stage beamforming. The user scheduling and beamformer design method includes 1) a two-step feedback approach, 2) the use of orthonormal reference beam vectors, 3) computation of the angle between the user's channel vector and each of the orthonormal reference beam vectors, 4) first-step feedback of the reference beam index to which the user's channel vector's angle is less than a certain threshold and feedback of the user's channel vector's norm, 5) selection of roughly orthogonal users with large channel norm based on the use of reference beam vectors and the channel norm feedback, 6) second-step feedback of the channel state information (CSI) from the scheduled users, 7) design of multi-user downlink beamformer for the scheduled users based on the second-step feedback of the CSI of the scheduled users. The main key point of this invention is that in the first step of user selection, we propose to use the channel norm or noise-plus-interference-divided channel norm as the feedback quantity and we propose to use only the angle between each of the reference beam vectors and the user's channel vector to identify the closest reference beam vector.

The invention discloses a multiple-input multiple-output method and a device. The method comprises the steps of: respectively generating a wave beam figuration weight corresponding to each user, respectively generating a reference wave beam figuration weight corresponding to each auxiliary scheduling user according a predetermined regulation, wherein the reference wave beam figuration weight is vertical to a signal space of a main scheduling user and the figuration gain is maximum, determining a channel quality indication corresponding to the auxiliary scheduling user according to the reference wave beam figuration weight corresponding to each auxiliary scheduling user, determining once transmission throughput of the auxiliary scheduling user according to the determined channel quality indication, choosing a reference auxiliary scheduling user to perform second order space division multiplexing with the main scheduling user from the auxiliary scheduling users, and in the event of meeting the preset conditions, performing space division multiplexing on the reference auxiliary scheduling user and the main scheduling user according to the reference wave beam figuration weight of the auxiliary scheduling user and the wave beam figuration weight of the main scheduling user. The throughout in district and the system frequency spectrum efficiency are promoted.

The invention provides a pseudo-random code phase tracking method and a code tracking ring multi-path inhibition BOC (Binary Offset Carrier) code tracking method, which effectively inhibit multi-path effect according to structural characteristics of a BOC signal. A pseudo-random code generating step, a BOC code generating step, a reference waveform generating step, a relevant waveform constructing step, a mutual correlation step, a phase discrimination function generating step and a phase discrimination step are included. According to the invention, in the correlation waveform constructing step, the constructed forward correlation function and backward correlation function only have one peak value and good linearity is obtained; and a zero crossing point of a phase discrimination curve and a zero crossing point while no multi-path signal is available have no deviation when multi-path effect exists so that the offset of the tracking point is overcome to achieve the accurate distance measuring and positioning purpose.

In a demodulation process of a first modulated signal and a second modulated signal, phase adjustment is automatically performed by generating, in response to demodulation results, an optimum phase value of a second internal reference wave for demodulating the second modulated signal. A phase of a second internal reference wave for demodulating the first modulated signal is also adjusted using the optimum phase value for the automatic adjustment.