34results about How to "High signal-to-noise ratio gain" patented technology

The invention belongs to the communication signal detection field and the non-linear field and particularly relates to an adaptive stochastic resonance system and method based on an artificial fish swarm algorithm. The system comprises a normalized stochastic resonance module, an artificial fish swarm adaptive module, a step adjustment module, a noise adjustment module and an iteration control module. Through the system, not only can a problem of difficulty in setting an optimization searching initial value of an adaptive system be solved through normalized stochastic resonance, adaptability is improved, no stochastic resonance, excessive stochastic resonance and insufficient resonance caused by parameter selection are considered, relatively strong search capability is kept through a step function adjusted according to resonance convergence conditions, but also local optimum can be properly discovered and jumped out from, and optimal value convergence efficiency is accelerated. An input signal to noise ratio is optimized through the noise adjustment module, and system signal to noise ratio gain is substantially improved.

The present invention discloses a channel estimation method based on comb-type pilot frequency for a DDO-OFDM system. The method comprises the steps of (1) obtaining a pilot frequency position, (2) inserting a pilot frequency subcarrier at the frequency pilot position in the sending signal of an emitting end, (3) extracting the pilot frequency subcarrier for a receiving signal at a same pilot frequency position at a receiving end, (4) using LS estimation average method to estimate the average frequency response of the pilot frequency subcarrier, and (5) using a linear interpolation method to estimate the frequency response of the data subcarrier in a channel. In the same pilot frequency expenditure, the error rate is reduced by the algorithm of the present invention, the estimation accuracy is raised, and the SNR gain is raised. The pilot frequency expenditure influence on the algorithm error rate is small, the low error rate can be ensured even in small pilot frequency expenditure, the frequency band utilization rate is raised, the complexity of the algorithm is low, and the practicability is high.

The embodiment of the invention provides a joint detection method and device for a broadband multi-user scene, and the method comprises the steps: carrying out the estimation of channel parameters ofa target sub-band, and obtaining the channel state information of the target sub-band; receiving a signal on a target sub-band to be accessed, and estimating the received signal by using the minimum Euclidean distance according to the channel state information to obtain an estimated signal; increasing the signal-to-noise ratio gain of the estimation signal in a time-frequency domain, and detectingthe signal after the signal-to-noise ratio gain in a space domain to obtain a detection statistic of an access target sub-band; receiving detection statistics sent by other secondary users of the target sub-band to be accessed, and fusing the detection statistics to obtain fused detection statistics; and comparing the fused detection statistics with a preset threshold value, and determining whether the target sub-band has a detection result of the main user or not. Visibly, by applying the method provided by the embodiment of the invention, the accuracy of accessing the secondary user can beimproved.

In order to effectively process small target infrared images under the low signal to noise ratio complex background, the invention discloses a small target infrared image processing method based on the weighing local image entropy and relates to the technical field of digital image processing. Inherent features of the small target infrared images are utilized, a multi-scale gray difference operator and a local image entropy operator are provided, the weighing local image entropy is obtained through the dot product operation, so that the infrared image background and the noise are effectively restrained, a target is enhanced, and finally the signal to noise ratio of the images is greatly improved.

The invention discloses an orthogonal space-time block code transmission method based on an optimal relay linear weighting matrix, which solves the problems of high error rate and poor transmission performance in the traditional method. The orthogonal space-time block code transmission method is realized by the following steps: (1) a communication system formed by a source node S, a relay node R and a destination node D is set; (2) at a first time slot, the source node S sends signal vectors x1 and x2, and the relay node R receives data yr1 and yr2; (3) the relay node R carries out singular value decomposition on a channel matrix H1 from the source node S to the relay node R and a channel matrix h2 from the relay node R to the destination node D; (4) the relay node R constructs an optimal linear weighting matrix W; (5) at a second time slot, the relay node R constructs and sends signal vectors xr1 and xr2 to the destination node D; and (6) the destination node D receives data yd1 and yd2 and constructs a judgment vector to decode. The orthogonal space-time block code transmission method disclosed by the invention has the advantages that: since the signal-to-noise ratio of received signals is increased, the system error rate is reduced, and the system transmission performance is improved.

The invention discloses a method and a device for capturing navigation signals. The method comprises steps: to-be-processed data segments are selected, the to-be-processed data segments are delayed sequentially for a delay step, and N data groups are obtained; the coherent integral value of each data group is acquired, and the first largest coherent integral value, a left neighbor coherent integral value and a right neighbor coherent integral value are determined; when the absolute value of the difference between the left neighbor coherent integral value and the right neighbor coherent integral value is smaller than or equal to a threshold value, the first largest coherent integral value is determined to be the coherent integral value not including navigation data bit hopping and can be used for capturing and deciding the navigation signals; and when the absolute value of the difference between the left neighbor coherent integral value and the right neighbor coherent integral value is larger than the threshold value, through comparing the left neighbor coherent integral value and the right neighbor coherent integral value, a fine searching direction is determined, and through the fine searching, the coherent integral value not including the navigation data bit hopping is determined. Thus, the computational efficiency during the navigation signal capturing process can be improved, and the signal-to-noise ratio gains are improved.

The invention belongs to the PN code FFT parallel acquisition method in wireless communication technology, including: the generation of the short pseudocode set at the transmitting end, the generation of baseband modulation signals, the up-conversion processing and signal transmission; the generation of the short pseudocode set at the receiving end, signal reception and Down conversion processing, frequency domain matching for correlation, large number judgment. The invention converts the long pseudo-code into G short pseudo-codes, and each short pseudo-code is cascaded to generate a short pseudo-code set; the receiver simultaneously uses the same cascaded short pseudo-code set to perform frequency domain matching related processing , and then use a large number of decisions based on chip delay; thus, it has little sensitivity to channel noise, does not need accurate channel estimation and high acquisition accuracy, and uses a large number of decisions to improve the robustness of the decision criterion Features. In the Rayleigh channel, when the acquisition probability of the invention is 95%, the required signal-to-noise ratio is about -13dB, which is about -1dB compared with the required signal-to-noise ratio of the background technology, and the gain of the signal-to-noise ratio is increased by about 12dB.