179 results about "Frequency demodulation" patented technology

A multi-stimulus controller for a multi-touch sensor is formed on a single integrated circuit (single-chip). The multi-stimulus controller includes a transmit oscillator, a transmit signal section that generates a plurality of drive signals based on a frequency of the transmit oscillator, a plurality of transmit channels that transmit the drive signals simultaneously to drive the multi-touch sensor, a receive channel that receives a sense signal resulting from the driving of the multi-touch sensor, a receive oscillator, and a demodulation section that demodulates the received sense signal based on a frequency of the receive oscillator to obtain sensing results, the demodulation section including a demodulator and a vector operator.

A receiver for broadcast signals, e.g. DAB, FM, DVB, and digital or analog short-wave RF broadcast signals according to the present invention includes a polyfunctional circuit (5) that can be switched into three modes and performs the digital frequency demodulation which is needed for the reception of a frequency modulated signal in a first mode A, a digital frequency adjustment of the receiver in case of the reception of a digital or analog modulated broadcast signal like DAB, DVB, DRM or AM in a second mode B and the digital frequency adjustment and the digital gain control of the receiver which is needed in case of the reception of a digitally modulated broadcast signal like DAB, DVB, DRM in a third mode C. Depending on the needed functionality not all of these modes need to be realized. Nevertheless, the same hardware will be used for different purposes although the circuit is realized with an optimized amount of hardware to realize an efficient receiver.

A receiver, which is adapted for demodulating signal carriers at variable frequencies to provide received signals at a plurality of different received frequencies, is calibrated to compensate for a frequency-dependent imbalance in the amplitude and/or the quadrature phase of analog in-phase (I) and quadrature (Q) received-signal components that have passed through receiver circuit paths that may cause such imbalance. I-channel and Q-channel Rx-correction coefficients for each of a plurality of different calibration frequencies are estimated and stored in a lookup table. Rx-correction coefficients for a calibration frequency or frequencies that are the same as or closest to the received frequency or frequencies are accessed from the lookup table and combined with digital I and Q components of received signals that have been provided by analog-to-digital conversion of analog I and Q components of received signals that have passed through the imbalance-causing receiver circuit paths upon demodulation at the received frequency.

A parameter-free method to analyze sensor signals incorporates two or more of frequency demodulation, amplitude demodulation and phase demodulation of the raw signal data. The resulting signal is transformed to a frequency domain, and target fault characteristics from the demodulated signal are identified. The method is used to detect faults in bearings, gears and other mechanical components.

The invention discloses a microwave frequency measuring method based on optical power detection and a device thereof, which conducts real-time measurement on microwave frequency by adopting a system consisting of an electro-optical modulating module and a frequency demodulating module. A continuous microwave signal is loaded on a continuous light source in the modulating module in the modulating manner of carrier suppressed small signals, and only generates two plus or minus 1 stage optical margin strips; the modulated optical signal is divided into two paths, wherein one path is injected into a comb-like filter with sine-function transmission spectrum while the other path is injected into a tunable optical attenuator; the output optical power of the two paths are detected and compared with each other and the microwave frequency is obtained from the demodulation of power ratio. The invention lowers the complexity and cost of the system, eliminates the influence of fluctuation of output power of the light source on the measurement of the frequency and enlarges the measuring frequency band of frequency linear demodulation.

A spectrometer and spectrometry method comprising modulating a light source with a carrier waveform multiplied by an envelope function, directing light from the light source through a sample region and to a photodetector, and demodulating current from the photodetector at a reference frequency. Also a method for computing a modulation waveform comprising specifying a target detection efficiency in a Fourier space, computing a response of a waveform that comprises a carrier wave multiplied by an envelope function, and modifying the envelope function using nonlinear optimization means to minimize a difference between the computed response and a predetermined target gain spectrum.

The invention discloses a fiber laser static-state strain beat frequency demodulation system based on single-sideband frequency sweep modulation. The system comprises a pumped source, a coupler, a first wavelength division multiplexer, a second wavelength division multiplexer, a first polarization controller, a second polarization controller, a sensing fiber laser, a reference fiber laser, a first isolator, a second isolator, a first beam combiner, a second beam combiner, a first broadband photoelectric detector, a second broadband photoelectric detector, a control processor, a narrow linewidth laser light source, a third isolator, a third polarization controller, a third beam combiner, a suppressed carrier single-sideband modulator, a fourth beam combiner, a frequency sweep signal generator, a phase modulator, a radio frequency signal generator, a frequency stabilization source and a photoelectric detector. The system provided by the invention realizes high-precision static-state strain measurement of the fiber lasers and solves the problems of incapacity of realizing high-precision static-state strain measurement, influences exerted by tunable laser frequency sweep non-linearity on demodulation precision, and the like by use of a conventional fiber laser demodulation technology.

The invention discloses an underwater acoustic measurement method for scattering properties of a ship target broadband radar, which is characterized by comprising the following steps of: firstly, inversely arranging a scaled model of a measured ship target in an anechoic tank, regulating basic conditions of a measurement device and a modeling test, simulating irregular sea waves at an interface between the scaled model of the ship target and water, amplifying a linear frequency demodulation signal generated by a signal source and radiating the amplified frequency demodulation signal in a sonic signal manner, amplifying and filtering an echo output signal reflected by the scaled model and then storing, then acquiring a plurality of groups of echo signal data on each rotating angle and then storing; and finally, processing the echo signals of the scaled model of the measured ship target on different rotating angles by adopting a pulse compression technology to obtain one-dimensional distance image data of the measured ship target. The invention overcomes the defects of rigorous requirements on measurement equipment and environment and incapability of measuring sea-surface target characteristics in the prior art, and has the advantages of flexibility in the measurement method, low cost, easiness in realization and the like.

Aspects of a method and system for a shared GM-stage between in-phase and quadrature channels may include processing an in-phase (I) component signal for the I channel and a quadrature (Q) component signal for the Q channel via one or more shared transconductance stages in a frequency demodulator. The I channel may be isolated from the Q channel and the Q channel may be isolated from the I channel using isolation resistors. The values of the isolation resistors may be selected so as to balance the isolation and signal attenuation. A folding circuit, comprising active devices, may isolate the I channel from the Q channel. A generated voltage may be utilized to bias the folding circuit. An oscillator for the I channel may be isolated from a mixer for the Q channel and an oscillator for the Q channel may be isolated from a mixer for the I channel.

The invention provides a fault feature extraction method and a fault feature recognition method of a vibration signal of a rolling mill chatter mark, and belongs to the field of rolling mill fault monitoring. The fault feature extraction method analyzes the vibration signal of the chatter mark via autocorrelation demodulation based on a second-order cycle, so unstable vibration signal of chatter mark is processed through frequency demodulation, a demodulated second-order cycle autocorrelation function is sliced according to time domain, and modulation information of the chatter mark vibration signal is kept completely. Therefore, accuracy of fault feature extraction of the vibration signal of the chatter mark is improved. The fault feature recognition method recognizes whether the rolling mill faults exist or not by the form of power spectrum information entropy, influence of rolling mill speed fluctuation needs not to be considered, and the recognition method is simple and accurate.

The invention discloses a digital frequency demodulation phase noise measuring device and method and belongs to the electronic measurement technology field. A digital phase-locked loop is utilized torealize carrier frequency tracking and phase locking of a to-be-measured source, an intermediate frequency amplifying unit is utilized to realize adaptive adjustment, an original digital frequency demodulation unit is utilized to extract noise, and plural average of the frequency domain is utilized to improve the phase noise measurement sensitivity of a system. The method is advantaged in that when phase noise measurement can be realized through the frequency demodulation method, compatibility of frequency offset and sensitivity indexes is analyzed, and the better near-end phase noise measurement sensitivity can be realized; the realization scheme is simple, system configuration is concise, the technology is relatively mature, realization cost is low, and the cost performance advantage isrealized to a certain degree.

The invention discloses a combined time frequency distribution and compression sensing radar frequency smeared spectrum interference method. The method includes obtaining radar echo signals and conducting down conversion processing to obtain the radar echo baseband signal s, conducting u domain frequency sweep filtering and frequency demodulation to obtain radar eco baseband signal x after frequency demodulation, setting the discrete time sequence x(n) of x, sequentially calculating the vector form Xi<^> of the non-overlapping slide window short time Fourier Transform time frequency distribution of the Xi<^> and Xi<^> of x (n), establishing the linear relation between the Xi<^> and x, setting the time-frequency point screening threshold, screening the time-frequency points contained in the Xi<^> to sequentially obtain the time-frequency points retained in the Xi<^> and a time-frequency point screening matrix Psi<^> of the Xi<^>, setting the vector form of Xi<^> after time-frequency points screening as Xi<^> bar and obtaining the linear relation among the Xi<^> bar, Psi<^> bar and Xi<^>, setting the x frequency spectrum as X, further establishing the linear relation between the Xi<^> bar and X, conducting reconstruction and inverse Fourier transform for X to obtain a reconstructed frequency demodulation target signal X<^>, and conducting inverse frequency demodulation for the X<^> to obtain the target signal after inverse frequency demodulation.

The invention provides an underwater acoustic detection device based on a photoelectric oscillator. The device comprises a laser light source circuit, a photoelectric oscillation loop and a frequencydemodulation circuit. The device enables a phase-shifted fiber grating or a fiber grating F-P cavity interferometer to be embedded into a microwave photon filter, and uses an elastic cylinder to convert external acoustic wave changes into fiber grating stress or pressure changes, thereby enabling wavelength changes to be converted into the changes in the center frequency of the microwave photon filter, and enabling the frequency of the output microwave signal of the photoelectric oscillator to change. The underwater sound field detection is completed by analyzing the frequency changes by the digital signal demodulation technology. Compared to a conventional fiber optic hydrophone device, the device provided by the invention has higher accuracy, demodulation speed and signal to noise ratio,and a large dynamic range. The technical contents involved mainly include the microwave photon filter making technology, the multi-frequency photoelectric oscillation technology, the scalar sound pressure and three-dimensional sound field measurement technology, the signal demodulation technology, the packaging technology and the array multiplexing technology.

An apparatus and a method for generating an ATIP data are provided. The apparatus, based on a wobble signal generated by reading a re-writable compact disc, generates an ATIP data; the apparatus includes: a frequency demodulator for demodulating the wobble signal to generate an original ATIP data signal; an ATIP clock generating circuit for generating an ATIP clock signal based on the wobble signal; and a data generating circuit, coupled to the frequency demodulator and the ATIP clock generating circuit, for generating the ATIP data based on the number of the original ATIP data signal at a first logic level during one period of the ATIP clock signal. This apparatus uses the number of the original ATIP data signal at a first logic level during one period of the ATIP clock signal and the bi-phase rule to precisely generate the ATIP data.

The present invention relates to a method of simultaneously performing packet detection, symbol timing acquisition, and carrier frequency offset estimation in parallel using multiple correlation detection and a Bluetooth apparatus using the same, in which the Bluetooth apparatus receiving a frequency modulated signal includes a frequency demodulating unit converting the received signal into a similar amplitude modulated signal; and multiple correlation detectors generating multiple correlation indices from the converted signal, on a basis of an access address received from a link layer and a plurality of carrier frequency offset search windows. According to the present invention, since packet detection, symbol timing acquisition and carrier frequency offset estimation are simultaneously performed in parallel in the relatively long access address reception interval instead of the short preamble signal reception interval.

A multi-wavelength Brillouin fiber laser based optical fiber temperature sensor which is formed according to an optical fiber Brillouin gain effect, an er-doped optical fiber amplifying effect, a multi-level Brillouin scattering temperature effect and a heterodyning beat frequency demodulation principle comprises a narrow line width single frequency laser, an optical branching device, a polarization controller, an opto-isolator, an optical circulator, a single-mode sensing fiber, an er-doped optical fiber amplifier, an er-doped optical fiber being not pumped, a high-speed photoelectric detector and a frequency analyzer. The multi-wavelength Brillouin fiber laser based optical fiber temperature sensor has the advantages of being many in the number of wavelengths, narrow in line width, fixed in wavelength interval and stable in output. The multi-wavelength Brillouin fiber laser based optical fiber temperature sensor achieves heterodyning best frequency demodulating detection of a high-order stokes wave and high-accuracy high-sensitivity temperature measuring with the single-mode optical fiber which provides gain for the fiber laser being served as a temperature sending detect unit.

The invention discloses a method for confirming an optimal resonance frequency band based on a period target, and the method is characterized by adsorbing a vibration acceleration sensor to a tested rolling bearing pedestal to acquire vibration signals, creating a 1/3 binary tree filter bank to gain filtered complex envelope signals, calculating the periodical intensity PAR of each envelope signal, clearing the complex envelope signal kurtosis value less than a threshold value, calculating the kurtosis values of the surplus envelop signals, selecting the frequency band corresponding to the greatest-kurtosis complex envelope signal as the optimal resonance frequency band and the frequency spectrum of the envelope signal so as to obtain an envelop spectrum, in comparison with the fault feature frequency corresponding to the fault type in the rolling bearing, finally confirming the fault type of the rolling bearing; the method utilizes the substantive characteristics of the fault stimulation impact to avoid the non-periodic impact to interfere the resonance frequency demodulation band, and the method has robustness and can accommodate the confirmation process of the resonance frequency demodulation band so that fault feature extraction and diagnostic test can be automatically achieved.

A demodulation structure for a n-tap pixel, mainly for 3D time-of-flight (TOF) applications uses a 2-stage switch structure for demodulating a modulated electromagnetic wave. An almost arbitrary number of storage sites per pixel can be implemented enabling an almost arbitrary number of samplings captured during one exposure. It also provides the option to demodulate and integrate different phasing samples according to the different modulation frequencies within the same exposure.

The invention discloses an active infrared detection device. The device comprises an infrared modulating module, an infrared transmission module, an infrared receiving module and an infrared demodulating module, wherein the infrared modulating module modulates an infrared modulating signal according to a preset frequency; the infrared transmission module transmits the infrared modulating signal to detect an object; the infrared receiving module receives the infrared modulating signal reflected by the detected object; and the infrared demodulating module demodulates the infrared modulating signal according to the preset frequency. The active infrared detection device transmits and receives the infrared ray with a 'special mark' by a method for modulating and demodulating the transmitted infrared ray with the same frequency signal, eliminates most infrared jamming caused by environmental factors, and acquires excellent antijamming capacity.

A frequency analyzer uses a new approach to determine simple and multi-frequency components. The invention mainly comprises a complex filter and a frequency discriminator. The real number part of the input frequency can be represented by a frequency spectrum composed of both positive frequencies and negative frequencies. The complex filter receives an input signal through two sampling points, and then the frequency discriminator computes the phase difference between two sampled signals from these two consecutive sampling points. After applying an inverse trigonometric function, the demodulated frequency is derived from the phase difference. Using a complex function to derive the demodulated frequency is more advantageous in that many high-frequency sampling circuits become unnecessary, thus reducing the power consumption of the frequency demodulation circuit.