Papers by Keyword: STFT

Abstract: This paper presents the possibility of using advanced IT tools for the identification and analysis of biological signals on the example of electroencephalographic tests. Identification and numerical analysis of EEG signals from a person suffering from epilepsy during and between seizures is presented.

Abstract: According to the characteristics of PCM / FM signals, we propose a new method based on STFT resolve tune software. Firstly, the spectral characteristics of PCM / FM signal is given use of the spectrum PCM / FM signal is demodulated theoretical basis. This paper discusses in detail the basic principles of this demodulation method and implementation process, analyze the demodulation performance and complexity of the method.

Abstract: According to the characteristics of PCM / FM signals, we propose a new software-based STFT Demodulation algorithm. This paper discusses in detail the basic principles of this demodulation algorithm and implementation process, analyze the complexity of the algorithm, proposed a new method for the extraction and correction code synchronization. Simulation results show that the algorithm not only can effectively suppress the influence of various disturbances in the actual signal synchronization accuracy of the code, with better demodulation performance, and realization of the principle is simple, high efficiency, easy to implement software-oriented real-time treatment.

Abstract: Faced with complex electromagnetic environment and varieties of adaptive radar waveforms, radar signal analysis and identification becomes more and more complex. Considering two important physical quantities - time and frequency in modern signal processing methods, this paper proposes that the joint time-frequency analysis (JTFA) method based on fractional Fourier transform (FrFT) and short-time Fourier transform (STFT) is applied to adaptive radar signal processing. The simulation results show that the joint time-frequency analysis method is superior to single short-time Fourier transform, getting a better analysis of results. The joint time-frequency analysis method provides the joint distribution of the time domain and frequency domain for adaptive radar signal analysis and describes the relationship between signal frequency and time.

Abstract: For the variable speed estimation of wheel-bearings in strong background noise, a novel method with the short-time Fourier transform and BP neural network (STFT-BPNN) is proposed. In the method, it calculates the time-frequency spectrum with STFT technique. Then the instantaneous frequency is estimated by peak detection. Taking the instantaneous frequencies as the input vectors, the BP neural network is trained to fit the discrete instantaneous frequencies. The effectiveness of proposed method is demonstrated by simulation. Experimental results show that proposed method provides better performance on variable speed estimation for wheel-bearings.

Abstract: FPGA structures are common designed in Serial structure and Parallel structure. As the most efficient one, Parallel structure also could be divided into whole-parallel and half-parallel which we called pipe-line structure. Whole Parallel structure FPGA take a great advantage on speed but consuming enormous resources. Moreover, FFT cannot give enough details on Time-frequency domain. In order to avoid these disadvantages, proposed STFT processer plan on FPGA. Based on the research on algorithms STFT, we gave an improved pipeline structure FPGA design. Then this design implied high speed STFT which take both speed and precision into count on FPGA. At the last of this paper, we conducted signal test. In this step , any signals were all collected from actual work condition. And then verify the feasibility of the program through simulation and actual signal test.

Abstract: According to the characteristics of PCM/FM signal demodulation, the research based on short-time Fourier transform STFT software resolving method. First detected using STFT f1 and f0 corresponding spectrum energy, according to the comparison of two energy spectrum of element. Software demodulation system is discussed in detail the synchronous digital detection and software algorithms, analysis of demodulation performance of the algorithm. The simulation and test results verify the effectiveness of the method.

Abstract: Anti-jamming of GPS receiver is an important problem in navigation war, and this topic has been well researched recently. However, anti-jamming in the complex receiving environment has not been considered in the most of the researches. To solve this problem a cascade anti-jamming method is proposed in this paper. In this scheme, each channel of the received signal vector is processed by utilizing a method based on STFT, after the signal in each channel passed through the processor, a spatial processing has been employed to, suppress the reserved interferences. The results of simulations show that, it can be seen from the time-frequency spectrum before and after the first step processing that the single-tone and non-stationary interferences have been mitigated, and it demonstrates that the performance of the ideal classic Weiner filter can be achieved in the proposed method.

Abstract: To get accurate frequency information from doppler signal is very difficult. In order to improve accuracy of doppler radio fuze, a design scheme which is not only using doppler signal amplitude information but also using doppler frequency information, and comprehensive and these two aspects of information give out the fuze work distance. The solution we give out in this paper is that we realize the STFT by application of parallel process mass on FPGA and together with quick frequency selection mechanism. Then we could get the frequency information from the doppler signal. Test results show that by using short time window Fourier transform, we could realize time-frequency analysis of doppler signal in allow system time delay.

Abstract: This paper introduces that the Short Time Fourier Transform (STFT) could be applied to analyze the time-frequency characteristics of inter-harmonics in transformer. Compared with the traditional Fourier Transform, the STFT could acquire more clear result, and offers theoretical basis for inter-harmonic detection. The STFT is used to analyze the inter-harmonics by selecting proper window slides function in Matlab which can obtain more precise resolution for the time-frequency characteristics. This method is useful to eliminate the inter-harmonics in transformer. It is helpful to improve the quality of power.