22 results about "Cyclic correlation" patented technology

A federated mining method for multimodal data based on multiple security policies includes: a federated learning framework is used as a data mining model for distributed data mining; a multiple authentication mechanism is designed; a local edge node is selected to participate in a federated computation to obtain authenticated local edge node and aggregate a dataset; a multimodal data fusion and a multimodal data classification are performed on the dataset by a generalized multimodal data feature fusion model based on a multi-headed attention mechanism; and an adaptive perturbation mechanism based on cyclic correlation analysis and differential privacy is designed to add noise round by round and dynamically. A federated mining method for multimodal data is further provided.

The invention relates to the technical field of signal processing, in particular to a joint estimation method and system for time domain parameters of multiple time-frequency overlapped signals, and the method comprises the steps: obtaining a generalized cyclic correlation entropy spectrum of the multiple time-frequency overlapped signals, reconstructing the generalized cyclic correlation entropy spectrum through a compressed sampling matching pursuit algorithm, removing redundant information, and improving the definition and resolution of the spectrum; the speed and precision of spectrum peak searching are improved through an improved grey wolf optimization algorithm, spectrum peak searching is carried out on generalized cyclic correlation entropy spectrum projection, and therefore joint estimation of the carrier frequency and the code element rate is achieved. According to the method, joint estimation and correction of the Cramer-Rao bound in the alpha stable distribution noise environment is deduced, and the method is used for evaluating the effectiveness of the method. When the method is used for reconstructing the entropy spectrum, the influence of impulse noise can be suppressed, so that the reconstructed entropy spectrum is sharper and more gathered; the method has low calculation complexity and higher estimation precision, is suitable for efficient joint estimation of multi-signal time domain parameters, and meets the multi-signal processing requirement in a complex environment.

The application discloses a kind of distributed antenna system joint timing and frequency offset estimation method, it belongs to communication technical field.The application aims to solve the problem of poor real-time performance of existing DAS synchronization method for joint estimation of multiple time offsets and multiple frequency offsets in DAS.The application proposes a method for joint timing and frequency offset estimation in DAS based on the good correlation characteristics of CAZAC sequence and multiple antenna synchronization sequences, which can simultaneously estimate the time offset and frequency offset of different transceiver antenna pairs.The application uses sliding cross-correlation operation and effective peak detection to estimate the time offset and integer multiple frequency offset of different transceiver antenna pairs, and uses cyclic correlation operation to estimate the fractional multiple frequency offset of different transceiver antenna pairs.Furthermore, the application uses simultaneous detection to achieve joint estimation of the time offset and frequency offset of different transceiver antenna pairs, which has low complexity and high real-time performance, and can ensure the accuracy of the estimation result.The application can be applied to timing and frequency offset estimation of distributed antenna system.

The invention discloses a high-speed modulation and demodulation method for a dynamic underwater acoustic network, and the method also employs an orthogonal sequence multiplexing modulation and demodulation technology based on a Zadoff-Chu (ZC) sequence, and combines the setting of a cyclic displacement interval to construct a plurality of sub-channels, thereby achieving the multi-path separation, and reducing the average transmitting power of a system at the same time. In the aspect of multi-user access, interference among multiple users is regarded as additive white noise by using quasi-orthogonal characteristics among different ZC root sequences, so that uncoordinated random concurrent access is supported; differential modulation between sub-channels in a symbol is adopted, and the requirement for phase tracking is lowered; and a receiving end converts multipath amplitude information into soft decision information through cyclic correlation spectrum calculation and multipath diversity technologies, so that the calculation complexity is reduced, and the throughput of the time-varying underwater acoustic system is improved while the multi-user access efficiency is improved.

The present invention belongs to the technical field of communication signal detection, and discloses a method for quickly capturing multi-rate communication signals under low signal-to-noise ratio, mainly solving problems such as slow signal detection speed, single method for selecting statistics, and decreased capture ability in a low signal-to-noise ratio environment when performing time-domain serial capture on signals with different code rates. The implementation steps are as follows: (1) pre-group the possible range of the signal code rate; (2) sample and quantize the received signal; (3) calculate the zero-delay slice of the cyclic correlation of the received signal to estimate the carrier frequency of the signal; (4) intercept the processed signal, slide and select multiple delay slices for accumulation, construct a statistic adapted to the change of the code rate, and perform a rough estimation of the signal code rate; (5) according to the rough estimation result of the code rate, select the best slice of the cyclic correlation to obtain the accurate value of the code rate. The present invention has the advantages of high flexibility and real-time performance, fast capture speed, high capture accuracy, etc., can quickly capture signals in a low signal-to-noise ratio complex electromagnetic environment, and is beneficial to the establishment of a fast communication link.

Embodiments include methods for a radar receiver, including receiving a composite signal corresponding to a transmitted radar signal. The composite signal comprises a plurality (M) of signal streams corresponding to a respective plurality (M) of signal pulses in the transmitted radar signal. Each signal pulse includes a main pulse and a cyclic extension (CE). Each signal stream includes delayed samples corresponding to a plurality of propagation delays of the corresponding signal pulse. Such methods include performing a cyclic correlation of each signal stream with a replica of the main pulse of the corresponding signal pulse, thereby generating a delay-time plane comprising a plurality (M) of correlation streams including samples corresponding to the plurality of propagation delays. Such methods include performing a plurality of DFTs on the correlation streams to generate a delay-Doppler plane. Such methods include searching the delay-Doppler plane for magnitude peaks corresponding to detected objects.

This invention discloses a low-power DTMB transmitter carrier recovery and constellation mapping enhancement method and platform, belonging to the field of terrestrial digital television broadcasting technology. The transmitter samples feedback signals from the intermediate frequency (IF), RF preamplifier, or power amplifier output. Based on the PN420, PN595, or PN945 frame header characteristics, it performs cyclic correlation, sliding correlation, or segmented correlation to obtain frequency offset, phase error, and correlation confidence, and drives a digital phase-locked loop to complete transmitter carrier self-calibration. The system generates non-uniform pre-scaling and pre-rotation parameters based on the feedback constellation error, causing the antenna port constellation to converge to a standard DTMB constellation; enhanced constellation mapping is enabled when supported by a dedicated receiver. The low-power control module reduces power consumption and improves transmission quality based on correlation confidence, EVM scheduling correlator, phase calculation, constellation pre-compensation, digital predistortion, and Doherty power amplifier bias.

An underground slurry communication transmission method belongs to the technical field of petroleum drilling engineering, adopts a cyclic PN sequence for information transmission, and comprises the following steps: 1) generating a group of cyclic PN sequences; (2) at a transmitting end, signals collected underground are mapped to a cyclic PN sequence through a mapping rule, an underground valve is controlled through the cyclic PN sequence to generate pulses, and the pulses are transmitted through a mud medium; and 3) at a receiving end, constructing a cyclic PN sequence receiving system, performing synchronization through a detection means in a matrix form to obtain synchronous bias, performing cyclic correlation operation on a signal and the converted cyclic PN sequence, and resolving information sent by a transmitting end. According to the invention, the cyclic PN sequence is adopted to replace the traditional Marry coding, the defect of low information rate of the traditional coding mode is overcome, and the cyclic PN code can effectively reduce the error rate in the signal transmission process; in the synchronization process, a detection means in a matrix form is adopted, the synchronization accuracy is improved, and it is ensured that underground signals can be accurately and efficiently transmitted back to the ground.

The embodiment of the invention provides a sampling control period calculation method of a self-balancing robot and related equipment. The method comprises the following steps: acquiring a kinetic model and motor control input information of the self-balancing robot; based on the kinetic model and the motor control input information, calculating sampling control description information of the self-balancing robot for any interval moment included in the preset sampling interval; acquiring an instantaneous energy functional, a cyclic correlation energy functional and an interval accumulated energy functional corresponding to any interval moment of the self-balancing robot, and constructing cyclic energy constraint information based on the instantaneous energy functional, the cyclic correlation energy functional and the interval accumulated energy functional; and performing negative qualitative analysis on the cyclic energy constraint information in combination with the sampling control description information, and calculating a sampling control period corresponding to the self-balancing robot. Therefore, the maximum allowable sampling control period can be obtained through calculation, and communication and calculation resources are saved while stable operation of the system is ensured.

The application discloses a kind of integrated signal generation and multi-target clustering identification method and device of feeling.This application uses unified AFDM waveform as bottom transmission mechanism, realizes full diversity gain in time-frequency plane by adjusting affine parameter, effectively suppresses the inter-subcarrier interference under high dynamic scene.In the receiving end, the distance-Doppler heat map is reconstructed by fast cyclic correlation radar algorithm, and the original detection point cloud is extracted combined with 2D-CFAR detection.Introduce the DBSCAN clustering algorithm based on dimensionless weight, and the scattered point is condensed into an independent entity target in RDM physical space, and the radial velocity characteristics of clustering centroid are used to construct automatic decision engine, to realize the real-time classification and identification of static obstacles and dynamic moving targets.The application solves the technical pain points of traditional ISAC system in high frequency, high mobility scene, such as sensing point fragmentation and confusion of static and dynamic targets.