39results about How to "Against interference" patented technology

A synchronous method of orthogonal frequency division multiplexing symbol timing for multi-path fading channel environment, which is specially used for the OFDM system under the multi-path fading channel environment. Concretely, it includes following steps: 1) judging time range of the window starting point of effectively sampling for non-symbol interference in receipt signal; 2) processing preliminary sampled signal, using it to recover the OFDM signal; 3) obtaining the symbol timing estimate by coherent detection. The invention can effectively confront the inter-symbol interference produced by the multi-path fading, and can obtain comparatively accurate timing estimate under low SNR condition, which solves the problem of lowered synchronization property caused by the disrupted dependence of circulation prefix for complex channel environmental low system's SNR in prior art.

The invention discloses an orthogonal time-frequency space OTFS modulation equalization method with low computational complexity, which is a method for equalizing interference between two-dimensionalcodes of an orthogonal time-frequency air conditioner under a time-frequency double-selection channel based on iterative parallel interference elimination of a linear minimum mean square error. The method can effectively utilize the covariance matrix of the reconstructed symbol to alleviate the influence of the interference between the residual two-dimensional codes on the OTFS system performance,so that the time-frequency two-dimensional gain can be better utilized, and the system reliability can be improved; time-frequency two-dimensional decomposition and octyl Fourier transform are adopted to carry out first-order Newman series approximation on the inverse matrix in LMMSE-PIC, so that the calculation complexity of the equalization method is reduced, and the equalization method only has a directrix relation with the total number of transmission symbols and is irrelevant to the channel sparsity, so that the system effectiveness is improved. The orthogonal time-frequency air conditioning system has the advantages that the time-frequency two-dimensional diversity gain of the orthogonal time-frequency air conditioning system can be remarkably improved under the time-frequency double-selection channel, the receiver performance of the non-ideal channel decoder during feedback is improved, and the popularization and application prospect is good.

The invention relates to a multi-dimension hybrid spread spectrum system and method based on a high speed bus and a graphic processing unit (GPU), belonging to the technical field of communication. The multi-dimension hybrid spread spectrum system comprises a transmitting unit, a GPU, a receiving unit and a data main control unit, wherein the transmitting unit comprises a transmitting antenna, a transmission radio-frequency module and a low and medium frequency/baseband transmitting module; the receiving unit comprises a receiving antenna, a reception radio-frequency module and a low and medium frequency/baseband receiving module; and the data main control unit comprises a high speed bus and a main control/buffer and display module. The invention adopts the technologies of multi-input and multi-output, space-time coding, parallel processing and high-speed transmission reception diversity, and combines a direct spread/frequency hopping hybrid technology, so that the overall system integrates the advantages of three dimensions of space, time and frequency, and the confidentiality and anti-jamming ability of the realized hybrid spread spectrum system are further greatly expanded; and very quick data transmission and quick code synchronization and code acquisition performance of the multi-dimension hybrid system are realized by the advantages of the high speed bus and GPU architecture.

The invention discloses an MIMO (Multiple-Input Multiple-Output) radar preference optimization netting method in a multi-surveillance area. Firstly, a surveillance area and a netting area are determined, an objective function is determined, and a reference point is set according to preference information; then, with the reference point as the guide, a particle swarm optimization algorithm based on preference is used for reasonably optimizing an antenna netting position; and finally, from outputted netting schemes, a netting method closest to the reference point is selected for reasonable radar netting. The surveillance performance of a preference surveillance area can be enhanced, and more radar optimization netting methods can be acquired.

The invention discloses a long-distance large-data-volume wireless communication method for unmanned aerial vehicles, which can not only realize digital transmission of wireless video data, but also counteract interference problems in wireless channels so as to improve the transmission reliability of the wireless transmission system. This method forms video data by superimposing the video images taken by the UAV and the performance parameters during the flight of the UAV; then compresses and encodes the video data, and finally transmits the encoded video data to the client, and the prediction-based HARQ algorithm is used for error control in wireless transmission, which can not only realize the digital transmission of wireless video data, but also use the prediction-based HARQ algorithm to control the error of the wireless transmission channel Control, can counteract the interference problem in the wireless channel so as to improve the transmission reliability of the wireless transmission system. It is suitable for popularization and application in the field of wireless transmission technology.

The invention provides a communication system and signal sending method and apparatus as well as signal receiving method and apparatus thereof. The signal sending method comprises: based on channel information, carrying out channel coding and constellation mapping on each sub-data stream to be sent, carrying out multiple input multiple output sending process on the sub-data stream which has been subjected to the channel coding and constellation mapping, and carrying out OFDM modulation on the sub-data stream which has been subjected to the multiple input multiple output sending process, and outputting OFDM symbol data stream obtained after the OFDM modulation to a transmitting antenna for transmitting. The OFDM modulation comprises the sub-data stream which has been subjected to the multiple input multiple output sending process is inserted with pilot symbols of corresponding antenna ports and is mapped to corresponding physical subcarriers; and subcarriers in element units corresponding to the sub-data streams are expanded to whole or partial system bandwidth to form mapping with the physical subcarriers based on the preset mapping relation. The technical scheme in the invention is capable of effectively resisting the influence of frequency selective fading.

The invention relates to a system and a method for eliminating intersymbol interference of an ultrawideband signal of a multi-path noise-free channel. By setting an appropriate threshold value, a receiver searches an ultra-wideband signal pulse, and the detection is succesful until a signal level exceeds the threshold value; then, a signal window is used for extracting a received signal, and a detected composite signal pulse (formed by mixing a signal pulse and more than one multipath interference signal) is placed in the middle of the signal window; the received signal is processed through anintersymbol interference (ISI) eliminator before demodulation, so that the intersymbol interference is eliminated. According to the method, channel information or channel estimation does not need tobe acquired in advance, and analog-digital conversion is not needed; the expected signal pulse and the interference pulse can be distinguished and accurately positioned through the method; and a traditional receiving pulse is not used during signal demodulation, and a signal peak generated after wavelet transformation and high-pass filtering is used.

The invention provides a soft spreading code optical selection method of a mixed spread spectrum multiple-access network; the method comprises the following steps: setting limit conditions according to structure characteristics of a cyclic shift keying (CCSK) code, and forming a code database satisfying proportionality and autocorrelation requirements; employing an origin traversal-initial random-end segment directed segmented search method to screen a set of soft spreading codes satisfying cross correlation requirements from the autocorrelation code database; finally combining with a frequency hopping pattern so as to reasonably distribute the soft spreading codes to each network for usage. The method can effectively reduce the internetwork interferences, thus improving the system networking ability.

The invention belongs to the technical field of radar signal processing, and discloses a target detection waveform optimization and processing method for an agile coherent radar, which comprises the following steps of 1, optimizing a baseband signal waveform in a pulse of the agile coherent radar by using a nonlinear frequency modulation signal waveform, 2, establishing an echo model based on the agile coherent radar after waveform optimization, and obtaining an echo matrix, 3, performing pulse compression processing on the agile coherent radar after waveform optimization to obtain a pulse compression matrix, and 4, conducting coherent processing on the agile coherent radar after waveform optimization, and realizing improvement of target detection performance of the agile coherent radar. According to the method, the target detection performance of the agile coherent radar is improved in a strong clutter and strong interference environment, active deception jamming and aiming suppressing jamming of the radar can be effectively resisted, the detection distance farther than that of a non-coherent frequency agile radar can be achieved, and higher real-time performance is achieved by adopting a coherent accumulation algorithm.

The invention relates to a high-accuracy pulse power detection module which comprises a radio-frequency circuit for receiving a radio-frequency input sampling signal and a radio-frequency output sampling signal. An output end of the radio-frequency circuit is connected with an input end of a detection circuit for receiving sampling voltage V1 and sampling voltage V2, and an output end of the detection circuit is connected with a fault indication circuit. The high-accuracy pulse power detection module can simultaneously detect an over-temperature connecting point, voltage V1 sampling, voltage V2 sampling, radio-frequency input sampling and radio-frequency output sampling, can monitor input and output power variation of a forestage component in real time to accurately judge whether input power and output power are faulted or not, voltage stability can be monitored in rear time to accurately judge whether an under-voltage condition exists as voltage reduces or not, no power output is caused, fault reasons can be effectively and rapidly found, and the component is conveniently maintained.

A multi-carrier MISO (Multiple Input, Single Output) system based on a three-dimension mutual-complementing code relates to an MISO system, and aims to solve the problem that a conventional MISO system is poor in multi-path interference resistance and multi-user interference resistance. Each user k adopts a three-dimensional mutual-complementing code as a signature code, each three-dimensional mutual-complementing code consists of NT two-dimensional mutual-complementing codes, and for each user k, the working procedures of the system comprises the steps as follows: step I, at a transmitting end, data to be sent is modulated to NT paths of modulation signals by utilizing a transmitter of the MISO system, and then the NT paths of modulation signals are transmitted to wireless signal channels via NT antennae; and steps II, at a receiving end, the transmitters of the MISO system is utilized to receive the NT paths of modulation signals transmitted to the wireless signal channels in the step I with one antenna. The system is applicable to the field of wireless communication.

The invention discloses a method for estimating the direction of arrival of a polarization area array under main lobe interference based on spatial domain-polarization domain self-adaption. The method comprises the following steps of firstly, receiving data according to each array element of an area array to obtain a spatial domain-polarization domain joint adaptive weight, outputting data of a row of linear arrays, and then solving an azimuth angle of a target by adopting a maximum likelihood method algorithm; receiving data according to each row of array elements of an area array to obtain a spatial domain-polarization domain joint adaptive weight, outputting data of a column of linear array, and then solving a pitch angle of a target by adopting a maximum likelihood method algorithm. According to the method, multiple interferences in a main lobe can be resisted through spatial domain-polarization domain joint self-adaption, a problem that the target angle estimation precision is low due to the fact that spatial domain self-adaption under main lobe interference can cause main beam distortion is solved, and polarization self-adaption can only resist one interference in the main lobe although the main beam distortion cannot be caused.

The present invention relates to a modulation and transmission method of biorthogonal interference, and is applied in the field of communication, so as to enhance the security of communication system. In the generalized Fourier series, the method adopts an algorithm of inverse transform to acquire the biorthogonal function family from a basis function; two groups of functions in the biorthogonal function family are respectively used at the receiving end and the transmitting end of the transmission system. The receiving end adopts one group of functions to complete the interference modulation of the signals; the receiving end adopts the other group of functions to complete the interference decomposition of the received signals, so as to acquire the information. The method can be used in the transmission system.