55results about How to "Improve demodulation efficiency" patented technology

The invention discloses a photon orbital angular momentum mode measurement method and system based on helical transformation. The method comprises the following steps: a phase plate at an input planemaps an incident light field to a straight line of an output plane along a helical path on the input plane, and the phase plate at the output plane compensates the phase accumulated by propagating thelight field to the output plane from the input plane in the above transformation process, thereby a the to-be-tested photo orbital angular momentum mode at the input plane into a plane wave mode withthe specific tilt wave-front at the output plane; and then a convex lens focus the plane wave modes with different tilt wave-fronts on different locations of the focal plane, thereby realizing one-to-one corresponding and detection of the to-be-tested photo orbital angular momentum mode and the space location. The adjacent model crosstalking problem caused by demodulation facula widening is effectively overcome, and the high-resolution photon orbital angular momentum mode measurement is further realized when the high demodulation efficiency is maintained.

The invention relates to a digital demodulation method and a digital demodulation device for frequency modulation and amplitude modulation signals, and belongs to the technical field of electronic measurement. The digital demodulation measurement of the frequency modulation and amplitude modulation signals is realized in a virtual instrument way, local area model parameter values such as amplitude and frequency of a sinusoidal carrier signal sequence are obtained by utilizing a partial waveform of less than a waveform cycle, and a sinusoidal model of less than a waveform cycle is subjected to sliding fitting on an actually-measured curve waveform, so that the digital demodulation of the modulation signals is realized. In addition, the method and the device have the characteristics of high temporal resolution, high robustness, small demodulation distortion, absolute convergence, rapid demodulation and the like. The method and the device are high in temporal resolution and robustness, an algorithm is absolutely convergent, and tracing and calibration are facilitated.

Disclosed are a code modulation method and apparatus for high order modulation. The method comprises: converting information that needs to be transmitted into a bit data stream, and demultiplexing the bit data stream into more than one channel of bit data stream; performing first-type coding on at least one channel of bit data stream in the more than one channel of stream, to obtain first output data; performing second-type coding on at least one channel of the remaining channels of bit data stream on which the first-type coding is not performed, to obtain second output data; and performing quadrature amplitude modulation on the first output data, to generate a modulation symbol for output. Compared with the prior art, the correctness rate of demodulation in the technical solution is improved significantly, achieving higher transmission efficiency.

The invention relates to a digitalized measurement method and device for modulation delay of a light frequency modulator, and belongs to the technical field of photoelectric measurement. The device comprises a frequency stabilized laser, a polarizing film, a half wave plate, a light splitter, a frequency shifter, a reflector, a measured light frequency modulator, a modulation signal source, a reflector, a half-transparent and half-reflecting mirror, a polarizing film 11, a photoelectric detector, a digital oscilloscope, and an electronic computer. A measured object is the time delay between an excitation control signal of the light frequency modulator and a regulated and controlled light frequency signal. A heterodyning-type laser interferometry device is employed for obtaining laser frequency regulation and control signal waveform of the light frequency modulator, and converts a light signal into an electric signal. The method can achieve a good convergence effect, is higher in measurement accuracy, and is well adapted to the condition that the carrier is not steady and the amplitude envelope changes severely.

The invention relates to a large dynamic range heterodyne interferometry type fiber optic hydrophone system which comprises a narrow linewidth laser, a first coupling, a first acoustic optical modulator, a second acoustic optical modulator, a first optical fiber delay ring, an acoustic optical modulator driver, a second coupling, a first circulator, a second circulator, a first photoelectric detector, a second photoelectric detector, a reference probe, a sensing probe and a signal demodulating module, wherein an optic signal output by the narrow linewidth laser is converted into two pieces ofpulse light with different frequencies through the first and second acoustic optical modulators, the pulse light intervenes through the probe of the fiber optic hydrophone to beat frequency to obtaina heterodyne signal of a certain frequency, and the system expands the dynamic range of the heterodyne interferometry type fiber optic hydrophone by improving the frequency of the heterodyne signal ofbeat frequency, so that the demand on measurement of large-range signals is met.

The embodiment of the invention discloses a method and a receiver for realizing phase synchronization of coherent light. The method comprises the following steps that analog/digital conversion of a signal acquired after frequency mixing of a received coherent light signal and a local oscillation signal is carried out and the converted frequency mixing signal comprises the frequency deviation and phase noise of the coherent light signal and the local oscillation signal; the phase error of the frequency mixing signal is extracted by means of logarithm and comprises the frequency deviation and the phase noise; and the phase error is removed from the frequency mixing signal. The method and the receiver extract the phase error acquired after frequency mixing of the received coherent light signal and the local oscillation signal by means of logarithm and then remove the extracted phase error from the frequency mixing signal, thereby realizing the phase synchronization of the received signal and the local oscillation signal, preventing the signal of a coherent communication system from generating phase ambiguity and increasing the accuracy of the phase synchronization and the demodulation efficiency of a receiving system.

The invention discloses a data modulating and demodulating method as well as a frequency spectrum management method, device and system. The frequency spectrum management method comprises the following steps of: acquiring a target frequency band allocated for a transmitting terminal; calculating a precoded codeword index formed by a frequency spectrum according to a codebook corresponding to a current radio scene and the target frequency band, wherein the codeword index corresponds to a zero return sub carrier sequence which is used for calculating a precoding vector for modulating data; and broadcasting and transmitting the precoded codeword index. By implementing the embodiment of the invention, a receiving terminal can be used for knowing pre-filtering operation of the transmitting terminal according to the pre-coded codeword index; and the data are demodulated according to the precoding vector, and thus transparent transmission from the transmitting terminal to the receiving terminal is realized and the demodulation efficiency is improved.

The invention discloses a hybrid modulation and demodulation method for atmospheric laser communication. Multi-pulse pulse position modulation and high-order polarization shift keying modulation are mixed together, a Stokes parameter is extracted for a polarization state of the light during the demodulation, the polarization state is almost constant after atmospheric transmission, the three-dimensional demodulation of the Stokes parameter has a larger coding space and decision space compared with the one-dimensional demodulation or two-dimensional demodulation, therefore the anti-interferenceperformance is high, moreover, the coding space and the decision space are expanded by using the three-dimensional demodulation, so that the PolSK can be pushed to multi-order use on the premise of ensuring the bit error rate performance; whether a time slot receiving signal is an additive white gaussian noise signal is judged by using the extracted Stokes parameter at a receiving end, so that whether a pulse is received within the time slot can be judged, and the demodulation of the pulse position is finally achieved; and by adoption of the method, the use of the signal amplitude demodulationposition in the traditional method is avoided, the demodulation process is simplified, and the demodulation efficiency is also improved.

The invention relates to an FBG sensor network spectrum demodulation method based on an improved simulated annealing method. The FBG sensor network spectrum demodulation method comprises the steps of:S1, expressing a mathematical expression of reflection spectra of an entire FBG sensor network according to mathematical characteristics of the FBG sensor network and the measured reflection spectra,reconstructing the mathematical expression of the reflection spectra, and regarding a variance of mathematical expressions of incident spectra and the reflection spectra; S2, adopting a particle swarm algorithm to search for a solution of an objective function, adopting the improved simulated annealing method to perform annealing operation after every particle position update before the optimal solution is obtained, so as to avoid the calculated solution from falling into a locally optimal solution; S3, and regarding the obtained optimal solution as a reflection spectrum central wavelength value of each FBG in the FBG sensor network. Compared with the prior art, the FBG sensor network spectrum demodulation method improves the demodulation efficiency of FBG spectral multiplexing, increasesthe overlapping demodulation number of grating spectra, and overcomes the limitation that wavelength ranges of different gratings cannot overlap.

The invention provides an optical wavelength detector. The optical wavelength detector is formed by arranging n tunable F-P cavity filters in parallel. The resonant cavity thicknesses of the n tunable F-P cavity filters are characterized by step distribution. One end of the optical wavelength detector is provided with n optical input ports for receiving n paths of optical signals which serve as the inputs of the n tunable F-P cavity filters. The other end of the optical wavelength detector is provided with n optical output ports for outputting n paths of filtered transmitted optical signals. Under the control of an external tunable power supply, the n tunable F-P cavity filters make the F-P cavity filter passband wavelength periodically tuned. Simultaneous demodulation of multiple optical wavelengths can be achieved. Meanwhile, the optical wavelength detector has the characteristics of low cost, high integrated level, small volume and portability.

The invention discloses a signal demodulation method and device. The signal demodulation method comprises the steps of: obtaining received signals, wherein the received signals include a phase noise signal; on the basis of the received signals and a pre-set phase noise parameter, establishing a likelihood probability ratio integral model, wherein the phase noise parameter represents the phase noise signal, and is a random variable; performing phase rotation angle extraction transformation processing and discretization processing on the likelihood probability ratio integral model, so that a likelihood probability ratio discrete model is obtained, wherein the phase rotation angle represents the phase rotation angle obtained based on the phase noise signal; and, on the basis of the likelihoodprobability ratio discrete model, determining the likelihood probability ratio corresponding to the received signals, so that a demodulation result is obtained. Thereby, a base station performs phasecompensation and discrete calculation on the received signals, so that a demodulation result is obtained; therefore, the phase noise is overcome; and the signal receiving performance, the signal demodulation efficiency and the signal demodulation accuracy are improved.

The invention discloses an optical fiber sensing demodulation method based on digital filtering and binary pulse modulation. The method comprises the following steps: firstly, modulating and interfering a laser light source to obtain laser interference light intensity I<s> with phase modulation; secondly, calibrating the laser interference light intensity I<s> with a three-step phase-shift methodaccording to the difference between corresponding position times to obtain three-step phase-shift light intensity signals I<1>', I<2>' and I<3>'; thirdly, performing spectral analysis and low-pass filtering on I<1>', I<2>' and I<3>' to obtain new three-step phase-shift intensity signals I<1>, I<2> and I<3>; fourthly, processing I<1>, I<2> and I<3> with an anti-tangent method to obtain phase information theta'' of the laser interference light intensity; and finally performing bandpass filtering on theta'' to obtain an external vibration signal to finish demodulation. The method disclosed by theinvention has the advantages of low complexity, high efficiency, high noise immunity, capability of correctly demodulating the external vibration signal, and very good application prospect.

The invention discloses a method and a device for demodulating a convolution code. The method comprises the following steps of: at least two storage spaces capable of being read parallelly are confirmed in at least one storage device; state message parameters corresponding to each current state are grouped by taking the state as a unit, and each group corresponds to at least one storage space; the previous state message parameters needed by updating each group of the state message parameters are stored into at least two storage spaces according to a mapping relation between the previous state message parameters and the state message parameters corresponding to each current state; and each group of the current state message parameters are parallelly updated according to the previous state message parameters stored into different storage spaces respectively. The method and the device carry out grouping to the state message parameters corresponding to each state by taking the state as the unit, store the parameters needed by updating each group of the state messages into different storage spaces respectively, and then parallelly update each group of the state message parameters, thereby improving the demodulation efficiency.

Provided is an orthogonal demodulation device, which makes effective use of the result of an orthogonal detection so as to improve a demodulation efficiency. The orthogonal demodulation device comprises an orthogonal detector (DT) for orthogonally detecting a received signal obtained by receiving a radio wave from a radio discrimination tag, thereby to generate an in-phase signal and an orthogonal phase signal, and a demodulating circuit (DM) for detecting the preamble of a specific transition pattern from at least one of the in-phase signal and the orthogonal phase signal, for decoding at least one of the in-phase signal and the orthogonal phase signal so as to attain the data subsequent to that preamble, and for performing an error detection on the decoding result so as to confirm the existence of an error.

The invention discloses a method and device for dynamically adjusting a working mode of a radio frequency front end, and a mobile terminal. The method comprises the following steps: when the mobile terminal uses a high frequency signal of Long Term Evolution LTE, calculating the distance between the mobile terminal and a base station by acquiring the positions of the mobile terminal and the base station; and when the distance exceeds a maximum distance of uplink transmissive effective information of the mobile terminal, starting a high emission mode of the mobile terminal, and enabling the radio frequency front end of the mobile terminal to work under the high emission mode, so as to ensure that data sent by the mobile terminal at high frequency can be received by the base station, so thatthe demodulation efficiency of the base station is improved, and the problem that the actual network rate is low due to the fact that high-frequency radio electromagnetic wave attenuation is large inthe prior art is solved.

A demodulation apparatus and method using a code table that decreases complexity. The demodulation apparatus includes a code table including a plurality of the code words, wherein similar ones of the code words are arranged to be grouped together; and a soft demodulator to calculate probabilities of individual bits that constitute the code words, and to generate a soft demodulation value of the data word.

The invention discloses a method and device for demodulating three-dimensional tip clearance. The device includes a tip clearance three-dimensional fiber detection probe having three independent elements, wherein the three independent elements acquire optical signals, outer ring optical signals and inner ring optical signals are further outputted, the three sets of outer ring optical signals and inner ring optical signals from the three independent elements are acquired by a pre-processing circuit, the pre-processing circuit includes a photoelectric conversion module, an amplification followermodule and a subtraction module, the three sets of outer ring optical signals and inner ring optical signals are converted by the photoelectric conversion module into six paths of corresponding photoelectric signals, and the six paths of corresponding photoelectric signals are amplified by the amplification follower module and outputted to the subtraction module and a single-chip microcomputer module. The device is advantaged in that the inner and outer ring light intensity signals of the three elements of the three-dimensional tip clearance fiber sensing probe are taken as input, the three sets of differential ratio signals are obtained through pairwise difference and ratio division, and the three-dimensional tip clearance information is demodulated through the three sets of differentialratio signals.

The invention relates to the technical field of phase demodulation, in particular to a Brillouin optical time domain reflectometer and a phase demodulation method and device thereof, and the method comprises the steps: determining the position and range of a disturbance point from an original signal; based on the position and the range of the disturbance point, extracting intensity signals of two different positions closest to the disturbance point; respectively carrying out high-pass filtering processing on the two intensity signals; respectively carrying out normalization processing on the alternating current components of the two processed intensity signals; performing differential cross multiplication and subtraction processing on the two normalized intensity signals respectively; and integrating the phase change after the subtraction processing to obtain a demodulation phase. The problems that an existing phi-BOTDR phase demodulation scheme is complex in demodulation process and low in demodulation efficiency are solved. The method has the advantages that the demodulation process is simple, consumed time is reduced, demodulation efficiency is improved, operation efficiency of the system is improved, and stability and accuracy of demodulation results are improved.