8 results about "Circular correlation" patented technology

An imaging method includes: (I) simultaneously illuminating a scene with a first (second) diverging wave originating from a first (second) location and modulated with a first (second) shift-and-add-qualifying-code. A scatterer that scatters the first (second) diverging wave as a first (second) speckle. (II) Detecting, with a receiver, an interference signal, produced from interference between the speckle fields, and including a code temporally shifted with respect to the first SAA-code by a large-scale time-shift. (III) Circulantly correlating the interference signal with a reference SAA-code to generate a correlation signal. (IV) Determining the time-difference-of-arrival from the large-scale time-shift. (V) Determining a location of the scatterer by: determining, from the time-difference-of-arrival, a hyperbolic contour that locates the scatterer angularly; and determining, from one of (i) a small-scale time-shift of a peak of the correlation signal and (ii) a ranging delay, an elliptical contour that locates a range of the scatterer from the receiver.

The present invention discloses a system and method for optimizing the logic circuit complexity of a spread-spectrum communication system. The system includes a data buffer module (RxBuffer), a local spread-spectrum sequence generation module (LocalCSSGen), an FFT-based time-domain circular correlation despreading module (RxDeCSS), and a despreading parameter control module (RxCtrlModul). The system utilizes a joint mechanism technology that combines local coarse correlation despreading of a low-sampling-rate complete symbol period sequence with fine correlation despreading of a high-sampling-rate truncated symbol period sequence for despreading spread-spectrum symbols. By dynamically setting the compression ratio of the buffer module and the local spread-spectrum sequence, accessing the initial index, and truncating the spread-spectrum sequence length, the system performance requirement for the FFT length is reduced, thereby reducing the complexity and difficulty of implementing the FFT logic circuit of the spread-spectrum communication chip, achieving chip area optimization, and promoting optimization of the overall area of ​​the spread-spectrum communication chip while ensuring high sensitivity and large capacity system requirements.

The application belongs to the technical field of synchronous signal capture, and discloses a kind of underwater acoustic PN signal time domain coarse capture method and system based on deep learning, adopt receiving end local carrier compression algorithm to convert PN correlation gain amplitude frequency deviation response into the approximate flat of multiple SINC function module non-coherent accumulation, based on the circular convolution of local carrier compression time domain parallel correlation result output is used for TCN-Seq2Seq model provides the correlation waveform feature of large doppler tolerance;Utilize TCN-Seq2Seq model to realize the time domain synchronization of low signal-to-noise ratio condition based on the circular correlation output waveform of carrier compression, identify and analyze the received waveform, output waveform time domain range, obtain the coarse estimation of Doppler frequency deviation, complete time domain frequency domain coarse capture.The application greatly reduces the computing overhead, and has high value for the application of underwater acoustic communication of PN signal in military and biological friendly direction.

The application discloses a prestressed CFRP plate end peeling damage bearing capacity calculation method and belongs to the technical field of bridge reinforcement. The method comprises the following steps: a finite element model of a concrete beam reinforced by end-bonded prestressed CFRP is established based on a fracture phase field method; through simulation, it is determined that the concrete strength, the prestress level and the thickness of the protective layer in the tension zone are key parameters affecting the peeling bearing capacity; based on the parameters, a bending peeling bearing capacity submodel and a shear peeling bearing capacity submodel considering the influence of prestress are respectively established; a bending-shear correlation equation is established by adopting a circular correlation curve fitting, and is used for comprehensively evaluating the peeling bearing capacity of the plate end section under the bending-shear combined action. The application overcomes the limitations of the traditional numerical method, such as the need to preset a damage path and the difficulty in parameter calibration when simulating a complex interface peeling, can accurately predict the plate end peeling damage bearing capacity of the end-bonded prestressed CFRP reinforced beam, and provides a reliable basis for engineering design and safety evaluation.

A loopback receiver to synchronize timing and frequency with a loopback signal relayed to the loopback receiver, the loopback receiver including: an Rx signal representing the loopback signal received at the loopback receiver; and a common Fast Fourier Transform (FFT) to estimate, during an acquisition mode and a tracking mode, an estimated timing offset and an estimated frequency offset of the Rx signal compared to the loopback signal, wherein the loopback signal includes a burst including a GOLD Pseudo Noise (PN) sequence having a good circular correlation and the GOLD PN sequence has cross-correlations within a set. Some embodiments may eliminate a bias of the estimated timing offset and the estimated frequency offset with double linearization.

This invention discloses a method for fast range ambiguity resolution of short-period direct-sequence spread spectrum signals used in radar measurement. The method comprises: 1) designing a square wave period based on the maximum unambiguous measurement range requirement; 2) transmitting a direct-sequence spread spectrum signal modulated with a square wave at the transmitting end; 3) estimating the code phase within the spread spectrum pseudocode period at the receiving end using fast circular correlation; and 4) despreading using the spread spectrum pseudocode phase estimation result and accumulating energy within the spread spectrum pseudocode period to obtain N. s The energy accumulation results are as follows: 5. The energy accumulation results within adjacent spread spectrum pseudocode periods are used to search for the square wave transition edge using a differential method to complete target detection decision and distance estimation; This invention can effectively improve the maximum unambiguous distance for capturing high dynamic weak signals, while resolving the contradiction between computing resources and acquisition time.

This invention discloses a multipath-resistant LoRa communication method combining block interleaving and matched filtering, belonging to the field of Internet of Things (IoT) technology. The steps are as follows: Block interleaving reduces the amplitude of strong multipath signals by dividing the signal into equal blocks and then swapping the order of these blocks, followed by deinterleaving at the receiver; matched filtering increases the signal-to-noise ratio (SNR). Matched filtering is selected based on amplitude criteria, first filtering the preamble symbol, then performing circular correlation operations using the preamble and data symbols. This method effectively resists multipath interference and improves the bit error rate performance of LoRa communication. It is low in complexity, low in power consumption, and simple to implement, making it suitable for multipath-intensive indoor and outdoor communication scenarios and shallow water acoustic communication.

This invention discloses a method for calculating the bearing capacity of prestressed CFRP slab end-peel failure, belonging to the field of bridge reinforcement technology. The method includes: establishing a finite element model of a prestressed CFRP-reinforced concrete beam at the end based on the fracture phase-field method; determining key parameters affecting peel bearing capacity, such as concrete strength, prestress level, and tensile zone protective layer thickness, through simulation; establishing bending peel bearing capacity sub-models and shear peel bearing capacity sub-models considering the influence of prestress, respectively, based on the parameters; and establishing a bending-shear correlation equation using circular correlation curve fitting to comprehensively evaluate the peel bearing capacity of the slab end section under combined bending and shear action. This invention overcomes the limitations of traditional numerical methods, which require pre-setting failure paths and face difficulties in parameter calibration when simulating complex interface peeling. It can accurately predict the end-peel failure bearing capacity of prestressed CFRP-reinforced beams, providing a reliable basis for engineering design and safety assessment.