441 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 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.

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.

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.

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.

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 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.

According to one aspect, the invention relates to a device (20) for three-dimensional imaging by full-field interferential microscopy of a volumic and scattering sample (1) comprising an emission source (201) for emitting an incident wave with low temporal coherence, an imaging interferometer (200) of variable magnification, allowing for the acquisition of at least one first and one second interferometric images resulting from the interference of a reference wave obtained by reflection of the incident wave on a reference mirror (205) and an object wave obtained by backscattering of the incident wave by a slice of the sample at a given depth of the sample, the at least two interferometric images having a phase difference obtained by varying the relative path difference between the object and reference arms of the interferometer, a processing unit (206) for processing said interferometric images making it possible to obtain a tomographic image of said slice of the sample, means for axially displacing the interferometer relative to the sample allowing for the acquisition of tomographic images for slices at different depths of the sample and means for varying the magnification of the imaging interferometer allowing for the acquisition of interferometric images of a slice of the sample for different magnification values.