30 results about "Cyclic autocorrelation function" patented technology

The invention belongs to the technical field of communication signal modulation analysis under non-Gaussian noise environments, and discloses a modulation parameter estimation method for OFDM signalsunder Alpha stable distribution noises. The method comprises the following steps: performing nonlinear transformation on received OFDM signals, and calculating generalized cyclic autocorrelation functions of the signals; extracting specific cyclic frequency sections of the generalized cyclic autocorrelation functions, and implementing available symbol length estimation on the OFDM signals by searching spectral peaks of the specific cyclic frequency sections; and extracting specific time delay sections based on available symbol length estimation, and implementing symbol length estimation on theOFDM signals by searching spectral peaks of the specific time delay sections. Under Alpha stable distribution background noises, when the mixed signal-to-noise ratio is greater than -1dB, the root-mean-square error of available symbol length estimation of the OFDM signals is close to 0, and when the mixed signal-to-noise ratio is greater than 3dB, the root-mean-square error of symbol length estimation of the OFDM signals is close to 0.

The invention discloses a single-antenna orthogonal frequency division multiplexing-based spectral domain signal transmission device and a single-antenna orthogonal frequency division multiplexing-based spectral domain signal transmission method. A transmission processing unit is embedded in the device, and comprises an inverse Fourier transform unit, NT shunt-wound power allocation units, a cyclic displacement processing unit, an adder and a cyclic prefix unit, wherein the power allocation units are used for performing power allocation on signals; the cyclic displacement processing unit comprises NT parallel cyclic displacement units, and performs displacement processing on the output signals of the NT power allocation units according to the principle of one-to-one correspondence to obtain NT displacement signals; the adder is used for accumulating the NT displacement signals to obtain a summation signal; and the cyclic prefix unit is used for attaching a cyclic prefix to the summation signal, and feeding the summation signal attached with the cyclic prefix into a single transmission antenna for transmission. The single-antenna device regulates and controls an orthogonal frequency division multiplexing signal cyclic autocorrelation function by a cyclic delay vector, reduces the requirements of the transmission device on the number of radio frequency antenna modules, and reduces the hardware development cost.

The invention discloses a transform domain communication system and a realization method thereof. The transmitting end includes a first random phase spectrum sequence generation module and a first inverse Fourier transform module, and is characterized in that it also includes a first CCSK modulation module, a second CCSK modulation module, an imaginary multiplier module and a tributary signal superposition module; The receiving end includes a second random phase spectrum sequence generation module, a signal conjugate module, a Fourier transform module, a first multiplier module, a second inverse Fourier transform module, a real number data extraction module, an imaginary number data extraction module, a first a peak search module and a second peak search module. The system and method of the present invention utilizes the characteristic that the maximum value in the circular cyclic autocorrelation function is a real number, and loads the basic modulation waveform through the real number branch and the imaginary number branch respectively to load different data streams, thereby improving the data transmission rate of the transform domain communication system , thereby improving the system spectrum utilization.

A method is provided for sending at least a first data signal and a second data signal, the data being divided into data blocks of fixed size including a header field of predetermined size, the data signals being sent to at least one data processing device adapted to apply a cyclic autocorrelation function with parameter k enabling the first and second data signals to be identified. The value of the parameter k is a function of a ratio between the size of the data blocks and the predetermined size of the header field. The method includes modifying the size of the header field of the data blocks before sending the first data signal, the value of the parameter k and the size of the data blocks remaining unchanged. A method is also provided for processing signals sent in accordance with the sending method.

The invention discloses a time domain parameter blind evaluation method of OFDM (Orthogonal Frequency Division Multiplexing) signals, which mainly solves the problems of poor evaluation performance and high calculation load of the traditional evaluation method under the conditions of low signal to noise ratio and multipath channels. The evaluation method comprise the steps of: designing a power spectrum of an approaching signal of an optimum cosine roll-off filter, and evaluating an oversampling rate; a calculating correlation coefficient function sequence of an OFDM baseband sampling signal,and evaluating an effective data length; calculating a cycle autocorrelation function of a signal moving autocorrelation function sequence, searching a cycle frequency corresponding to a peak value position of the cycle autocorrelation function, and evaluating a total symbol length; and evaluating a cycle prefix length by utilizing the evaluated total symbol length and the evaluated effective data length. The invention can ensure that the evaluation error of the oversampling rate and the total symbol length is small, the accuracy rate of the evaluation of the effective data length is high, and the performance of the evaluation of the total symbol length is free of the influence of frequency shift and phase shift, and the method can be used for the time domain parameter blind evaluation ofthe OFDM baseband sampling signals in the communication technical field.

The invention discloses an online fault diagnosis method and system for a centrifugal pump. According to the method, a vibration sensor is utilized for measuring a radial vibration signal in the operating process of a pump; the radial vibration signal is transmitted to a signal processing module; analysis treatment is conducted based on the cyclostationary theory so that a cyclic autocorrelation function can be obtained and subjected to slice analysis; feature parameters for distinguishing whether the pump breaks down or not and recognizing the breakdown type after it is determined that the pump breaks down are obtained; and a relevant breakdown diagnosis result is obtained by performing comparison and analysis on the feature parameters and corresponding parameters generated when the pump runs normally under the design working condition. According to the online fault diagnosis method and system for the centrifugal pump, diagnosis on mechanical seal damage and cavitation failures can be achieved by measuring the radial vibration signal of the pump, the running feature information of the pump can be reflected in the vibration signal in real time, the information integration degree is high, the number of signal transfer paths is small, the anti-jamming capability is high, and measurement reliability is high; and by analyzing stable components in the cyclic autocorrelation function of the signal, the situation that running is unstable due to the bias condition and consequently signal analysis is disturbed can be avoided, and specific reasons which cause unstable flowing of the centrifugal pump are identified.

The invention discloses a demodulation method and a demodulation system of a spectrum domain communication signal. The method includes: step 1, the cyclic autocorrelation function estimation value processing unit receives a continuous CDM-OFDM period whose length is one OFDM period The cyclic delay modulates the signal, and calculates the estimated value of the corresponding cyclic autocorrelation function; step 2, the cyclic delay detection processing unit calculates the corresponding likelihood functions for different cyclic delay values, and obtains the corresponding cyclic delay vector; step 3, the cyclic modulation vector demapping processing unit maps the cyclic delay vector to obtain the transmitted cyclic modulation signal. The present invention can be applied to spectral domain channel multiplexing transmission, increases system capacity without affecting ordinary OFDM signal transmission; adopts a block calculation method, greatly reduces calculation complexity, and saves processing time and resources.