33 results about "Signal-to-noise ratio (imaging)" patented technology

The invention discloses a hybrid image compressing method based on block classification. In the invention, blocks are divided into text/ image block, natural image block and hybrid block according to different features of text/image area and natural image area of original images in the aspect of color and texture; then a compression mode in which palette coding, Hextile coding and LZW coding are combined is used in the text/ image block, a JPEG lossy compression mode is used in the natural image while the algorithm of the combination of the two modes is used in the hybrid block. The invention has the advantages that based on the block classification method, the text/image area and the natural image area can be divided up accurately, and that the blocks are respectively encoded can keep rather acuminate edge of the text/image block so as to enhance visual effect on the basis of ensuring higher compression efficiency and upgrade the peak signal to noise ratio of reconstructed images; the complexity of the algorithm is lower.

The delay setting of an optical delay line interferometer (DLI) used to decode differentially encoded phase shift keyed signals (DPSK or DQPSK) is controlled using a control signal representative of the ratio P_err2/P_err1 of the rate of occurrence of double errors and the rate of occurrence of errors. The ratio P_err2/P_err1, as the delay setting of the DLI is varied, exhibits a characteristic W-shaped structure consisting of a local maximum at the optimum value and two minima adjacent to the maximum, one on each side of it. This structure is present over a wide range of signal to noise ratio and residual dispersion.

The invention provides a method aiming at the overall consideration and complexity of an uplink in a synergetic OFDM (orthogonal frequency division multiplexing) system for the resource allocation in a synergetic OFDM system. The method is characterized in that relays with the number thereof being a positive integer are arranged between a subscriber and a base station and each relay is provided with a plurality of subcarriers with the number being identical with that of the relays. The method comprises the following steps: firstly, the base station selects a relay according to the minimum equivalent signal-to-noise ratios of the subcarriers in each relay, that is, the base station selects the relay with the maximal equivalent signal-to-noise ratio of the subcarriers from the relays with the minimal equivalent signal-to-noise ratio of the subcarriers as the relay node for the subsequent synergetic transmission; then, the selected relay sequences the subcarriers between the subscriber and the selected relay and between the subscriber and the base station sequentially pair the subcarriers, namely, the subcarriers of the relay with high signal-to-noise ratio are used for transmitting the data supposed to be transmitted by the subcarriers of the subscriber with high signal-to-noise ratio; and finally, the base station carries out the water-filling power allocation on each intra-subcarrier according to the equivalent channel gain of each subcarrier pair, and starts the synergetic transmission.

The invention discloses a signal detection and judgment method and device in the capture of a weak satellite navigation signal. In a weak-signal environment, a high-sensitivity satellite navigation receiver needs to accumulate correlated results of a pseudo code for a long time so as to meet the sensitivity gain requirement of capture. The invention aims to reduce the SNR (Signal-to-Noise Rate) loss brought from a detection and judgment process of the correlated results by using a signal-based PAPR (Peak-To-Average Power Ratio) judging method and provides a self-adaptive treatment method for judging a threshold. Meanwhile, in the invention, the influence of a near-far effect is considered, and a judging module for removing cross correlation after primarily judging signal existence is provided so as to weaken the influence of the cross correlation interference of C/A (Coarse/Acquisition) codes. A control module carries out two-dimensional search on a capturer, and a method for detecting a maximum value falling trend is used for judging Doppler frequency shift existing in the current signal so as to shorten the search time of a frequency dimension and increase the capture efficiency. The invention is suitable for systems such as a GPS (Global Positioning System), BD-2 (BeiDou-2), and the like and can achieve the cold-boot capture sensitivity up to -145dbm.

The invention provides a quick beamforming method capable of improving array resolution and gain, comprising the following steps: adopting the construction of a minimum redundant array to optimize an M-element uniform linear array into a P-element non-uniform linear array; carrying out FFT processing on primitive data of a P-element array; in a frequency domain, constructing a covariance matrix of data based on the uniform linear array in accordance with the array aperture extension characteristics of fourth-order cumulants; carrying out normalization processing on the beam space and carrying out estimation on a Bartlett spatial spectrum. By adopting the array aperture extension characteristics of the fourth-order cumulants, the invention realizes that the optimized element layout form is employed to obtain high resolution and overcomes the defects of high requirements of the original fourth-order cumulant-based methods on snapshots and great computational complexity to enable the computation process to be simple and easy to operate. When the signal to noise ratio is higher than the supercritical signal to noise ratio, the method of the invention has higher array gain than that of conventional beamforming. The normalization processing of the beam space realizes effective inhibition to background interference. The beamforming method of the invention is simple and easy to operate and is especially suitable for project application.

The invention provides a double-fiber ball-shared coupling micro-measuring-force targeting sensor with an end face micro-structure, and belongs to the technology of precision instrument manufacture and measurement. The sensor comprises a laser device, a beam expanding collimating mirror, a fiber coupling lens, a guide pipe, a microscope objective, a CCD camera, a computer and a probe composed of an incidence fiber, a coupler and an outgoing fiber with the conical end face micro-structure. The coupler serves as a contact of the probe, and light beams are led out through the outgoing fiber with the conical end face micro-structure after being led into the coupler through the incidence optical fiber. The light beams which are led out enter the CCD camera through the microscope objective. The light spot energy center positions formed by the outgoing light beams on the CCD camera can be obtained through the image processing technology, and the targeting condition of the sensor in the space can be obtained through the one-to-one correspondence relation between the light spot energy center positions on the CCD camera and the spatial positions of sensor contacts. The outgoing fiber in the probe of the sensor is provided with the end face micro-structure, the signal to noise ratio of a detection signal is greatly increased, and the measurement resolving power of the sensor is improved.

A method for removing truncation artifacts in magnetic resonance images based on missing data reconstruction belongs to the technical field of image processing and comprises the following steps: detecting the magnetic resonance images with the truncation artifacts to obtain low frequency K data; carrying out Fourier inversion on the low frequency K data in the frequency encoding direction to obtain a truncated spectrum G (kx, y) of one-dimensional Fourier transform in the phase encoding direction; extracting singularities and singular value in the images of each row of data of G (kx, y) and reconstructing each row of data to obtain the high frequency partial K data; and carrying out Fourier inversion on the high frequency partial K data Fy(k) to obtain the row information fy(x) of the magnetic resonance images with the artifacts removed and storing and combining fy(x) based on rows to form the magnetic resonance images g(x, y) with the artifacts removed. The method overcomes the artifact problem existing during imaging by zero padding, ensures high signal to noise ratio of the images, effectively reduces the image errors, precisely displays the original magnetic resonance images, provides high quality reliable image information for medical nuclear magnetic resonance detection and is conductive to development and popularization of medical imaging detection technology.

The invention discloses a baseband receiving method and a baseband device applied to a terminal in a narrow-band wireless system, and relates to wireless communication technology. The baseband receiving method includes the steps: calculating LS (least squares) estimation values of an NRS (numeric rating scale) pilot frequency position, averaging LS results of the same subcarrier position in a subframe, and encrypting LS results of different carrier positions to obtain a list of results; calculating frequency domain correlation values, and distinguishing different gears of the correlation values. The list of encrypted LS results are filtered according to the distinguished gears, filter results serve as channel estimation values of all OFDM (orthogonal frequency division multiplexing) symbols on the subframe, noise power values are estimated according to the encrypted LS results, and finally, received signals are subjected to MIMO (multiple input multiple output) detection and demodulation according to the channel estimation values and the noise power estimation values. Compared with the prior art, the baseband receiving method has the advantages that the calculating amount of the baseband receiving process can be greatly reduced, the method is suitable for the narrow-band wireless system with low signal-to-noise ratio and low movability, and good receiving performance is achieved.

The invention discloses a local type fault diagnosis method of a rotating machine based on a sparse decomposition optimization algorithm, which comprises the following steps: S1, acquiring a rotatingmachine vibration acceleration response signal containing fault characteristic information; S2, intercepting a signal with an appropriate length, performing noise reduction pretreatment by applying ahigh-pass filter and singular value decomposition, and improving the signal-to-noise ratio; S3, setting an atom optimization criterion, and establishing a time-frequency domain correlation coefficientconstraint function of atoms and an actually-measured signal; S4, updating parameters of an initial random dictionary by using a particle swarm hybrid gradient descent algorithm to obtain an optimized impact response dictionary; S5, solving a sparse coefficient by using a segmented Lagrange contraction algorithm, reconstructing the fault characteristic signal according to the coefficient and thedictionary; S6, analyzing the impact response time interval of the reconstructed signal and demodulation of the characteristic frequency of the amplitude spectrum, identifying the position of the fault to finish the fault diagnosis. The dictionary has the advantages of high precision, high speed, stronger noise resistance and more accurate reconstruction characteristic signal.

Provided is a clock generator employed in a continuous-time sigma-delta modulator. The clock generator includes an oscillator configured to generate pulses in response to an enable signal, a counter configured to count the number of pulses generated by the oscillator and output the total pulse count, and an output circuit configured to output an inactivated output signal if the pulse count of the counter is equal to a pulse-width control bit. The oscillator includes an astable multi-vibrator. Since the astable multi-vibrator capable of generating a low-jitter pulse from a jittered clock is used as the oscillator, a signal-to-noise ratio is improved. A simple configuration using only digital circuits makes it easier to design a circuit and adjust pulse width. Moreover, according to the structure of the astable multi-vibrator, it is possible to design a circuit to optimally modulate pulse width in connection with process variations of resistors and capacitors used in the continuous-time sigma-delta modulator.

The invention discloses a chip-based side channel leakage analysis system and method. The system comprises a chip carrier, a probe seat, a probe, an information acquisition module and a workstation. The chip carrier is used for carrying a chip to be tested, the probe seat is used for carrying the probe, and the probe is used for obtaining information leakage of a target trace inside the chip to betested. The information acquisition module is connected with the probe and used for acquiring information leakage obtained by the probe. The workstation is connected with the information acquisitionmodule and used for processing and analyzing the information leakage acquired by the information acquisition module. The side channel leakage analysis system and method introduce the probe, and directly obtain the information leakage of the target trace inside the chip through the probe. Thus, the accuracy of an attack and the signal-to-noise ratio of the obtained curve can be improved, and certain security measures can be selectively bypassed to achieve a more comprehensive security assessment with practical operability.

The invention provides a common mode moving circuit for a multipoint low voltage differential signal receiver. The common mode moving circuit comprises a first resistor, a second resistor and a current regulating circuit as well as an error amplifier, wherein the current regulating circuit is formed by a third and fourth resistors and first to sixth transistors; grids of the second and fifth transistors are in a short connection with a drain electrode; grids of the first, second and third transistors are connected with each other and the source ends are grounded; grids of the fourth, fifth and sixth transistors are connected and the source ends are connected with power supply voltage; drain ends of the first and fourth transistors are connected with the first resistance; the third and fourth resistance is in a serial connection between a drain end of the second transistor and a drain end of the fifth transistor; drain ends of the third and sixth transistors are connected with the second resistor; a difference-mode input end of the error amplifier is connected with a reference level; and a common mode input end is connected with the drain ends of the first and third transistors. No effects are caused to input signal differential value; and the common mode moving circuit has system noise ratio higher than a receiver using a compression network.

The invention provides a fast multi-channel spectrometer for LED full spectrum detection. The fast multi-channel spectrometer comprises an optical system, a detector, a signal processing circuit, a single chip microcomputer main control system and a control signal generating circuit. The optical system uniformly irradiates light emitted by an LED to the detector, the structure of the optical system is a crossed Czerny-Turner system; the detector is an MOS linear array image detector S3901-256LVF, which is composed of a self-scanned photodiode array provided with a linearly variable filters; the signal processing circuit is used for driving the detector and amplifying a signal output by the detector; and the single chip microcomputer main control system controls the control signal generating circuit to generate two paths of input signals required by the signal processing circuit including a main clock signal and a main initiating signal. The fast multi-channel spectrometer can realize the diversification of test parameters, can detect a plurality of signals in parallel at the same time, has very short measurement time, is high in signal-to-noise ratio, has low requirement on stability of a light source, and can obtain spatial resolution and time-resolved spectrum without adopting mechanical scanning.

The invention discloses a dark field detection based optical-fiber macrobending coupling structure liquid-level probe. The liquid level sensing principle based on 'CMFTIR (cladding mode frustrated total internal reflection) effect' is proposed for the first time and applied successfully. By means of macrobending, mode field distribution in optical fibers is changed, ratio of cladding mode energy in the optical fibers is increased, and the CMFTIR effect is enhanced; meanwhile, due to macrobending radiation effect, macrobending coupling between the two optical fibers is realized; by means of macrobending coupling, a sensing signal is transferred to a dark field, modulation depth is increased during coupling, higher cladding mode energy ratio can be obtained in the passive optical fiber, and the CMFTIR effect is further enhanced; meanwhile, stability of the coupling structure and consistency of sensors are guaranteed, signal to noise ratio of increased by detection of effectiveness of dark field signals, the liquid-level probe is low in cost and power consumption and high in performance, and discrimination is higher than 4dB.

The invention provides an all-optical threshold device based on two-dimension material saturated absorption effect. The device comprises an optical amplifier arranged in the light transmission direction, and a saturable absorber connected with the optical amplifier, wherein the saturable absorber comprises an optical waveguide and a two-dimensional material covering the surface of the optical waveguide. The device is quite simple in structure, non-linear optical fiber or non-linear PPLN semiconductor devices are not needed, and the defects of the prior art that loss is large, stability is poor and cost is high are overcome. By the adoption of the device, the signal to noise ratio of received signals is increased, signal quality is improved, and the reception judgment performance of an optical communication system can be improved. The invention further provides a method for preparing the all-optical threshold device. The method comprises the steps of coating the surface of the optical waveguide with the two-dimensional material to form the saturable absorber, and connecting the optical amplifier with the saturable absorber through optical fiber to form the all-optical threshold device based on two-dimension material saturated absorption effect. The all-optical threshold device can be used for all-optical signal processing.

The invention discloses a light sensor comprising first and second thin film transistors, a voltage follower, a third thin film transistor and an output unit. First ends of the first and second thin film transistors and an input end of the voltage follower are connected to a first node. One thin film transistor in the first thin film transistor and the second thin film transistor is switched on inresponse to a control signal thereof, the third thin film transistor obtains the following voltage of the first node through the voltage follower and transmits the following voltage to the output unit, and a first digital voltage is outputted after conversion. The other one of the thin film transistors receives illumination to generate a light leakage current to change a potential of the first node, the third thin film transistor obtains the following voltage of the first node through the voltage follower and transmits the following voltage to the output unit, and a second digital voltage isoutputted after conversion. An embodiment of the present invention provides the light sensor, a light detecting method and a display device, and a signal to noise ratio and test accuracy can be improved.

The invention discloses a row driving circuit which comprises a plurality of cascaded driving units, and each driving unit comprises a pull-up control module, a pull-up module, a download module, a pull-down module, a pull-down maintaining module and a bootstrap capacitor. The pull-up module, the pull-down maintaining module, the pull-down maintaining module and the bootstrap capacitor are respectively connected with a first potential point and the scanning signal output end of the grid line of the level. The pull-up control module and the download circuit are respectively connected with the first potential point; wherein the pull-down maintaining module is used for receiving the second clock signal so as to maintain the potential signal of the first potential point and the grid line scanning signal of the stage in a low potential state, and the frequency of the second clock signal is twice or more than twice of the frequency of the clock signal of the stage. The invention further discloses a display device and a row driving method. The influence of the signal-to-noise ratio on the circuit can be effectively reduced, and the stability of the circuit is improved.

The invention relates to a blind estimation method for the signal to noise ratio of an OFDM system, and belongs to the technical field of wireless communication. Data subcarrier mean power and virtual carrier mean power are obtained on the basis of preambles of signal frames of the OFDM system, and further the signal to noise ratio is determined. Thus, the communication efficiency is higher compared with a pilot-aided estimation method for the signal to noise ratio in the prior art; the estimation precision is higher compared with a signal to noise ratio estimation method in which virtual carriers are used, and the blind estimation method of the invention is low in complexity, easy to realize and low in realization cost.

The invention discloses a speech recognition system and a speech recognition method. The speech recognition system includes a transfer function storage storing a vehicle transfer function, which represents an acoustic environment in a vehicle and frequency response characteristic of a microphone; a signal-to-noise ratio (SNR) estimator estimating an SNR of an input signal received from the microphone; a speech section determiner determining a speech section to which the vehicle transfer function is applied based on the SNR; a frequency pattern extractor extracting a feature pattern of the speech signal of which the frequency distortion is compensated; and a speech recognition engine recognizing a speech command by using the feature pattern.

Provided is a weak-light-signal multistage amplifying circuit. The circuit is characterized in that the circuit comprises a photoelectric detector, a prefixed amplifying circuit, a three-stage operation amplifying circuit and a one-stage amplifying detection circuit; the photoelectric detector is connected with the prefixed amplifying circuit, and the prefixed amplifying circuit is connected to the three-stage operation amplifying circuit and the one-stage amplifying detection circuit; after the photoelectric detector receives light signals, electric currents are generated, voltage signals are output after the electric currents go through the prefixed amplifying circuit, and the voltage signals are output to two operational amplifying circuits at the same time, wherein in one circuit, the voltage signals go through the one-stage amplifying detection circuit and output direct-current signals for detecting the direct-current magnitude of light signals, and in the other circuit, the voltage signals go through the three-stage operation amplifying circuit and output voltage pulse signals for detecting light-intensity changes. The weak-light-signal multistage amplifying circuit achieves the accurate measurement of micron-level matter, and can effectively suppress disturbance, improve the signal-to-noise ratio and obtain effective light signals.

The invention discloses a QPSK-DS communication detecting method based on delay multiplication. A system is initialized and begins to scan a target frequency band to amplify signals entering the system from the radio frequency front end, radio frequency signals are converted into fixed middle frequency to be amplified through a difference frequency method, digital signals can be achieved through analog-digital conversion, delay multiplication operation is carried out, digital lowpass filtering is carried out to obtain lowpass signals, and a frequency spectrum of the lowpass signals can be achieved through an FFT algorithm. The QPSK-DS communication detecting method has the advantages of adopting a linear and non-linear processing method to achieve full detection on QPSK-DS communication through simple comprehensive analysis and processing on time frequency domains and being simple to achieve, strong in operability and strong in capacity adapting to low signal to noise ratio. Meanwhile, the method adopts the middle frequency analysis instead of radio frequency or baseband processing to avoid high requirements for performance of processing capacity of a receiver as possible. Furthermore, the method can achieve real-time processing easily and is strong in practicability.

The invention discloses a minitype photoelectric sensor. The minitype photoelectric sensor comprises a light source device, an optical prism and a circuit board. The light source device is installed in the optical prism and electrically connected with the circuit board. The light source device is used for emitting a light beam. The circuit board is positioned below the light source device. The upper part of the optical prism forms an optical receiving lens which is used for collecting the reflected light beam. The lower part of the optical prism forms an optical condensing lens which is used for collecting the light beam received by the optical receiving lens to the circuit board. The circuit board is provided with a photoelectric receiving tube and a signal processing circuit. The photoelectric receiving tube is installed on a position, closest to the light source device, on the circuit board. The signal processing circuit is connected with the photoelectric receiving tube through thecircuit board. The beneficial effect is that the volume is tiny, the same optical prism is used for finishing the sending and the receiving of the light beam, a measuring distance of the photoelectric sensor is further improved, and a main working circuit of the photoelectric sensor is used, so the signal to noise ratio and the disturbance resisting capacity of the sensor are improved.

The invention provides a buried hill inner-screen imaging enhancement method and device based on signal-to-noise ratio field dynamic constraint. The method comprises: calculating the signal-to-noise ratio of each sampling point according to the signal energy and noise energy of each sampling point in seismic data; obtaining a denoising enhancement parameter of the sampling point according to the signal-to-noise ratio of the sampling point; carrying out imaging enhancement on the sampling point according to the denoising enhancement parameter of the sampling point. The method acquires a corresponding denoising enhancement parameter according to the signal-to-noise ratio of each sampling point, different denoising intensity parameters are used at different sampling points to achieve self-adaptive denoising for the buried hill inner screen; therefore, the problems that the difference of denoising effects of regions with different signal-to-noise ratios is extremely easy to cause, the difference is mainly reflected in excessive denoising and effective signal loss of a high signal-to-noise ratio region (such as the exterior of a buried hill), and denoising of a low signal-to-noise ratioregion (such as the inner wall of the buried hill) is incomplete, so that noise residues are caused, and finally accurate imaging of the inner wall of the buried hill cannot be realized are solved.

The invention provides an optical path adjustable pipe phase holdup detection system and method. The system comprises a pipe device, an optical path adjusting device, a light source emitter and a signal receiving device. The pipe device comprises an organic glass pipe located in the middle, and a large-diameter pipe, a transition tapered tube and a small-diameter pipe which are connected with twoends of the organic glass pipe in sequence. The optical path adjusting device comprises a first concave reflection mirror and a third concave reflection mirror which are set at the lower side of the organic glass pipe, and a first light guide mirror, a second concave reflection mirror and a second light guide mirror which are set in sequence at the upper side of the organic glass pipe. The first light guide mirror and the third concave reflection mirror are symmetrically set at two sides of a central axis of the second concave reflection mirror. The light source emitter is used for emitting visible light and near-infrared light. The system and the method are simple in structure. Free adjustment of an optical path is realized. The optical path is increased. A signal to noise ratio is improved. Measurement accuracy is improved. Real-time online detection can be realized.

Present invention discloses a forgery prevention holographical product property parameter detection method and instrument. Said Detection method utilizes displacement mechanism driving sample platform to proceed one dimension automatic scan, in scanning process photoelectric detector real time obtaining multipoint optical power signal, computer or microprocessor controlling light intensity signal collection, after software pretreatment to proceed analyse and process to collected said line data for measuring characteristic parameter, SNR and diffraction efficiency, and displaying and printing measuring result. Detect instrument includes light source, sample platform, displacement mechanism, photoelectricity receiving equipment, data acquisition and control module. Said invention realizes measuring automatization.

The invention discloses a civil aviation very high frequency ground-air communication radio station remote control device and a human voice discrimination method. An audio gating circuit is arranged between an audio preprocessing circuit and an audio amplification circuit; the audio gating circuit comprises an ADC (Analog to Digital Converter), a digital filter, a DAC (Digital to Analog Converter) and a switch which are connected in series, the ADC is connected with the output end of the audio preprocessing circuit, and the switch is connected with the audio amplifying circuit in series. The system also comprises a human voice discrimination module which is used for receiving the converted audio data from the ADC converter and carrying out human voice discrimination on the audio data. the voice discrimination module is introduced, and programmable chips such as a DSP (digital signal processor) and the like are adopted to discriminate voice and control output of received audio signals, so that squelch is realized, and the squelch accuracy of the civil aviation very high frequency ground-air communication radio station remote control box in severe weather or complex electromagnetic environment and the signal-to-noise ratio of the audio signals are greatly improved.