Papers by Keyword: Digital Filter

Abstract: The recordings of electrocardiogram (ECG), as an important biological signal which provides a valuable basis for the clinical diagnosis and treatment, are often corrupted by the wide range of artifacts. One important of them is power line interference (PLI). The overlapping interference affects the quality of ECG waveform, leading to the false detection and recognition of wave groups, and thus causing faulty treatment or diagnosis. The study deals with some of the signal processing approaches frequently used for elimination of PLI in ECG signal and compares the accuracy of methods by evaluation of the power of the remaining noise and comparing a filtered ECG signal with an original. The results are compared for three levels of interference and each tested method: Butterworth filter (BF), notch filter, moving average filter (MA), adaptive noise canceller (ANC), wavelet transform (WT) and empirical mode decomposition (EMD).

Abstract: The spectrum of the load component is retained and the spectrum of other components are eliminated by the identifying spectrum is processed with addition or subtraction in the frequency domain. The method avoids an error that Gibbs’ vibration is generated as the signals multiply each other in frequency domain is equivalent to the signals are convolution in time domain in the filtering. On the basis of Fourier transformation, the method only using addition or subtraction obtains useful frequency components. Compare with other processing methods, the processing result can satisfy the identifying requests. In practice, the method is simple and convenient and the operational error is less. It is a try for digital signal process.

Abstract: Piezoelectric Solid-State Micro-machined Modal Gyroscope is a new kind of gyroscope sensor based on MEMS. According to the characteristics of the gyroscope signal, the after-treatment processing system is designed and implemented, including A/D convertor by AD7656 and data storage by SD card. After applying Kalman filter to the digital signal on DSP, 71.8% decrease of standard variance of initial signal is achieved remarkably, which lays the foundation for the practical application of piezoelectric micro-machined modal gyroscope.

Abstract: With more and more distributed renewable energy connecting to the power system, inverters are widely used as the power electronic interface. However, high-order filters will inevitably bring in problems of resonance. Additionally, long-distance transmission and quantities of inverters increase the grid impedance obviously. Wide variation of grid impedance will not only impact on the resonance of filters, but also challenge stability of inverters system. This paper investigates how resonance and stability of grid-tied inverter with LCL-filter will be affected by the grid impedance. And a hybrid damping method based on RC parallel damper and biquad digital filter is proposed, this method presents relatively low power losses, requires no extra sensors and control loops with its simple damping strategy design. Moreover, it apparently improves system stability and waveform quality of grid-side current when grid impedance varies in a comparatively large range. Both validity and feasibility of this algorithm are verified via simulations.

Abstract: Intersymbol Interference (ISI) problem is one of the main factors affecting the baseband transmission performance of mobile communication’s digital signal which can not only reduce the transmission quality of the information but also can result in misinformation and false pass of information and provide troubles to the user and communications. In order to minimize the error rate, we propose a new digital equalization filter and establish the basic model of the digital filter and introduce non-linear Kalman observation equation and the state equation into the model and design partial differential mathematical model of the Kalman filter and develop MATLAB solver based on the mathematical model. In order to verify the validity and reliability of Kalman filter algorithms and mathematical procedures designed in this paper, it uses MATLAB toolbox to simulate the filter of mobile crosstalk signal and obtains amplitude-frequency characteristics and time-domain characteristics before and after filtering. By comparison, we can see that the filter can eliminate the high frequency crosstalk signal which provides technical reference for the study of the problem of crosstalk between the mobile communication codes.

Abstract: This paper presents a design and realization of a kind of portable wire rope testing equipment which based on the principle of nondestructive detection. A digital filter for noise removal, which is realized on STM32F103, is designed. GUI system is based on the QT platform, which has the characteristics of strong stability, high scalability, and the convenience of the operation.

Abstract: In MATLAB software, it has FDATool toolbox, which can design digital filter specific according to specific circuit, and analyze the performance of the filter according to the parameters of filter. In this paper we establish simulation mathematical model of digital filter based on the calculation principle of distributed multiplication accumulator. According to the logic algorithm we design delay algorithm of digital filter, and use MATLAB software to do simulation on amplitude frequency and phase frequency of digital filter. After superposition of different sampling frequency wave we get new waveform, and realize the digital filter for the new wave. It proves the availability of mathematical model and the program, and provides the technical reference for the design of digital filter.

Abstract: Quality of human pulse waveform graph determine the results of the disease analysis and affect disease diagnosis accuracy，Through the MATLAB software design of a digital filter is used to filter the pulse signals, Optimizing the pulse waveform graph. And the simulation test of digital filter, results showed that filter completed the pulse wave denoising.

Abstract: This paper introduced the hardware module, software process, and control mode and communication protocol of bulk solid flow control system based on the C8051F020. It selected the C8051F020 of transplanted uCos-II embedded operating system as the core, used the module software design idea, and realized the cooperation of collection, PID control, communication and other tasks. The industry site experiment showed that the system had good adaptability, stability and control effect, the control accuracy reached to ±1%FS, and the measuring accuracy reached to ±5.

Abstract: Calculus has been widely applied in engineering fields. The development of Integer order calculus theory is more mature in the project which can obtain fractional calculus theory through the promotion of integration order. It extends the flexibility of calculation and achieves the engineering analysis of multi-degree of freedom. According to fractional calculus features and the characteristics of fractional calculus, this paper treats the frequency domain as the object of study and gives the fractional calculus definition of the frequency characteristics. It also designs the mathematical model of fractional calculus digital filters using Fourier transform and Laplace transform. At last, this paper stimulates and analyzes numerical filtering of fractional calculus digital filter circuit using matlab general numerical analysis software and FDATool filter toolbox provided by matlab. It obtains the one-dimensional and two-dimensional filter curves of fractional calculus method which achieves the fractional Calculus filter of complex digital filter.