56results about How to "Improve demodulation efficiency" patented technology

The invention discloses a fast demodulation method. The method comprises the following steps of: making sure that M is equal to 2n and n is a natural number in a communication system using M-bit orthogonal amplitude modulation; and calculating log-likelihood ratio (LLR) of each output bit at a receiving end by using a simplified LLR formula, wherein only an item including a first specified symbol is retained in the numerator of an ideal LLR formula and only an item including a second specified symbol is retained in the denominator of the ideal LLR formula so as to obtain the simplified LLR formula; the first specified symbol is the symbol corresponding to a constellation point on a constellation diagram with a specified bit of 1 and having the minimum Euclidean distance with a receiving symbol; and the second specified symbol is the symbol corresponding to the constellation point on the constellation diagram with the specified bit of 0 and having the minimum Euclidean distance with the receiving symbol. Through the technical scheme, the method greatly reduces the complexity for calculating the LLR of the output bit, improves the demodulation efficiency, and also reduces the hardware cost.

The invention discloses a shared signal design method based on LFM signal phase / modulation frequency modulation. According to the phase modulation shared signal design method, a phase perturbation function is acquired based on randomly set amplitude parameters and phase parameters, and then the perturbation term of a shared signal is constructed; a shared signal is generated based on the perturbation term and a reference LFM signal parameter; and if a first design criterion is not satisfied, parameters for generating the phase perturbation function are adjusted for redesign until the first design criterion is satisfied. According to the modulation frequency modulation shared signal design method, based on a random number between (0, 0.5), an interval based on the frequency modulation slopeof a reference LFM signal is equally spaced; corresponding modulation frequency modulation parameters are calculated to construct the perturbation term of the shared signal; the shared signal is generated based on the perturbation term and the reference LFM signal parameter; if a second design criterion is not satisfied, parameters for generating the phase perturbation function are adjusted for redesign until the second design criterion is satisfied. The signal designed according to the invention has the advantages of good autocorrelation and cross-correlation characteristics and high demodulation efficiency.

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 self-recovery OAM mode communication system based on a composite phase hologram. The self-recovery OAM mode communication system comprises a spatial light modulator and a Fourier lens positioned behind the spatial light modulator and used for simulating diffraction, wherein the composite phase hologram is loaded on the spatial light modulator; and the composite phase hologram receives Bessel Gaussian beams and then modulates the Bessel Gaussian beams, a diffraction process is simulated through the Fourier lens, a demodulation result is subjected to Fourier transform, and the Bessel Gaussian beams in one or more OAM modes are simultaneously demodulated according to the demodulation result and are converted into perfect vortexes at the position of a focal plane. According to the self-recovery OAM mode communication system, the generated single or multiple composite BG light beams are incident on the MPH for demodulation and then are diffracted, demodulation can be completed at the focal plane position, and the BG light beams can be converted into perfect vortexes, so that interference caused by diameter superposition of the BG light beams with different OAM mode sizes is avoided, one or multiple OAM modes can be demodulated at the same time, and the demodulation efficiency of the OAM light beam is improved.

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.

In order to improve the efficiency of user signal demodulation processing including interference suppression processing, a wireless receiving unit (10) forming a wireless base station receiving device (1) receives a wireless signal (101) including plural user signal components respectively transmitted from plural mobile terminals. An interference suppression unit (20) determines whether to perform a predetermined interference suppression processing upon demodulation of each user signal component from the wireless signal (101) (base band signal (102) output from the wireless receiving unit (10)) according to a reception quality (reception quality information (107)) of each user signal component that needs to be guaranteed for each mobile terminal and a transmission rate (transmission rate information (108)) of each user signal component determined for each mobile terminal. At this time, the interference suppression unit (20) causes a number of interference suppression demodulation blocks (30) corresponding to the number of user signal components determined to be subjected to the interference suppression processing to operate, and causes a number of normal demodulation blocks (40) corresponding to the number of user signal components determined not to be subjected to the interference suppression processing to operate.

The invention provides an optical phase difference demodulation method based on a spiral interference image feature extraction technology. The method can be used for demodulating optical phase differences between two light beams. The method includes the steps: acquiring spiral interference images formed by interference of orbit angle momentum light beams and Gaussian light beams; extracting commonfeature images for analyzing a series of spiral interference images corresponding to different optical phase differences to obtain the common feature images of the spiral interference images; demodulating features, mapping the spiral interference images to two-dimensional space taking the common feature images as base vectors, and calculating coordinate values of the spiral interference images inthe two-dimensional space to achieve data dimension reduction of the spiral interference images; calculating the optical phase differences by the coordinate values in the two-dimensional space. According to the method, feature extraction is facilitated by the spiral interference images, data dimension reduction of the spiral interference images is performed, so that signal demodulating efficiencyis improved, and the influence of power fluctuation of the light beams on demodulating results of the optical phase differences can be effectively avoided.

The invention discloses a submarine natural gas pipeline leakage monitoring experimental platform and a data processing method thereof. The submarine natural gas pipeline leakage monitoring experimental platform comprises an optical path system, a photoelectric detection system, a signal processing system and a scene simulation system. The optical path system is provided with a first optical fiberset and a second optical fiber set in a connected mode. The first optical fiber set enters the scene simulation system in the clockwise direction and penetrates out of the scene simulation system, and the second optical fiber set enters the scene simulation system in the counterclockwise direction and penetrates out of the scene simulation system. The first optical fiber set and the second optical fiber set penetrate out of the scene simulation system and then are connected with the photoelectric detection system, and the photoelectric detection system is in circuit connection with the signalprocessing system. The submarine natural gas pipeline leakage monitoring experimental platform and the data processing method thereof have the beneficial effects that by adopting the experimental platform, the application number of optical instruments is greatly decreased, the loss of optical power on an optical path and unnecessary interference are greatly reduced, setting-up of the optical pathof the experimental platform is easy, and meanwhile, the experimental cost is reduced.

In order to improve the efficiency of user signal demodulation processing including interference suppression processing, a wireless receiving unit (10) forming a wireless base station receiving device (1) receives a wireless signal (101) including plural user signal components respectively transmitted from plural mobile terminals. An interference suppression unit (20) determines whether to perform a predetermined interference suppression processing upon demodulation of each user signal component from the wireless signal (101) (base band signal (102) output from the wireless receiving unit (10)) according to a reception quality (reception quality information (107)) of each user signal component that needs to be guaranteed for each mobile terminal and a transmission rate (transmission rate information (108)) of each user signal component determined for each mobile terminal. At this time, the interference suppression unit (20) causes a number of interference suppression demodulation blocks (30) corresponding to the number of user signal components determined to be subjected to the interference suppression processing to operate, and causes a number of normal demodulation blocks (40) corresponding to the number of user signal components determined not to be subjected to the interference suppression processing to operate.

An analog television (TV) receiver converts a received analog TV signal to a digital TV signal and performs digital demodulation to increase demodulation efficiency. The analog TV receiver includes a radio frequency (RF) turner and an intermediate frequency (IF) circuit. The RF tuner converts the received analog RF TV signal to an analog IF TV signal. The IF circuit includes a converting circuit and a digital demodulator. The converting circuit converts the analog IF TV signal to a digital TV signal. The digital demodulator demodulates the digital TV signal to generate a digital demodulated video signal and a digital demodulated audio signal.

The invention provides a wavelength demodulation method, the method comprising: S1. Under the control of the first voltage signal, the multi-longitudinal mode laser outputs n periodically changing light wavelengths at equal intervals, and is incident on the fiber grating sensor channel; S2 . Each FBG sensor in the FBG sensor channel reflects the matched wavelength in the incident light, and the reflected light contains the reflected wavelength information of multiple FBG sensors; S3. The reflected light is divided into n tunable filters; S4. Under the synchronous control of the first voltage signal described in S1, n tunable filters simultaneously perform wavelength filtering and demodulation on the evenly divided reflected light output by the power divider to obtain a plurality of fiber grating sensors reflection wavelength value. The invention can realize synchronous demodulation of multiple wavelengths.