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Introduction to Digital Filters
Published in John T. Taylor, Qiuting Huang, CRC Handbook of ELECTRICAL FILTERS, 2020
A digital filter is a system that can be used to manipulate the frequency spectrum of a discrete-time signal, e.g., to select or reject a specific frequency component, enhance or attenuate a range of frequency components, etc. A digital filter can be represented by the block diagram of Figure 1 where x(nT) is the input or excitation and y(nT) is the output or response. The excitation x(nT) may be generated by sampling a continuous-time signal x(t) at instants t = 0, T, 2T, …, but sometimes it may exist in its own right without a continuous-time counterpart, e.g., the closing price of a stock at the stock exchange as a function of time. The response is related to the excitation by some rule of correspondence which must of necessity entail some frequency-domain specifications.
Expert Knowledge-Based Direct Frequency Converter Using Fuzzy Logic Control
Published in Lakhmi C. Jain, N.M. Martin, Fusion of Neural Networks, Fuzzy Systems, and Genetic Algorithms, 2020
Sinusoidal three-phase systems produce sinusoidal two-phase systems when transformed by Park’s matrix, thus producing a rotating space vector of constant magnitude. This is not the case for the output line voltages reconstructed with (29), as the line voltages are pulses varying their average value in order to follow a sinusoidal reference. So, in order to obtain the desired line voltage’s space vector, the fundamental component of the line voltages is required. These are simply obtained by filtering the respective waveforms. To implement the filters, a digital approach is chosen, as it lacks all the problems associated to analog filters, specifically the parameters variation and the tuning of it. The digital filter is realized by software, and can be precisely designed to produce the required filtering characteristics.
Floating-Point Computations with Very-High-Speed Integrated Circuit Hardware Description Language and Xilinx System Generator (SysGen) Tools
Published in A. Arockia Bazil Raj, FPGA-Based Embedded System Developer's Guide, 2018
A fundamental aspect of digital signal processing is filtering. Filtering is a selective system which passes a certain range of frequencies by attenuating the other frequencies. A digital filter is a system that performs mathematical operations on the sampled or discrete time-variant signal to shrink or enhance certain aspects of that signal. In general, hardware programmability in FPGA introduces design overhead that results in 21 times more area, 3 times longer delay and 10 times more dynamic power consumption compared to ASICs [140,145,146]. This section briefs the architecture designs and optimization techniques aimed at bridging the FPGA-ASIC gaps. The explorations are based on the advanced FPGA reconfiguration model, called temporal logic folding, that partitions applications into a sequence of stages to temporally share the same hardware resources. The distributed high-performance low-power memory blocks enable cycle-by-cycle runtime reconfiguration without a large power overhead. The area usage is significantly reduced, which also improves the interconnect performance and power consumption. Next, observe that logic folding reduces area significantly and most interconnects are localized.
A low complexity and high modularity design for continuously variable bandwidth digital filters
Published in International Journal of Electronics, 2023
Sushmitha Sajeevu, Sakthivel Vellaisamy
Digital filtering is one of the most dynamic tools of digital signal processing. Compared to analog filters, digital filters are less sensitive towards environmental changes, more flexible, programmable and can be easily standardised since they are simply software modules. With the advent of VLSI technology, digital filters are employed in a wide variety of signal processing platforms. Variable bandwidth digital FIR filters have several critical applications in the field of speech signal processing, digital communications, biomedical signal processing etc. (Laakso et al., 1996; Stoyanov & Kawamata, 1997). Digital channelizer is a prominent part of the digital front end (DFE) in a software-defined radio (SDR)-based Internet of things (IOT) platform (Zeineddine et al., 2019). The ability to support multiple bands of signal frequencies according to the user demand is a special feature of SDR (Venosa & Palmieri, 2011). Sharp filtering is necessary to reduce interference from adjacent channels in a digital channelizer. Variable bandwidth digital FIR filter can be used as an efficient digital channelizer.
A novel approach to design optimal digital FIR filter based on logistic distribution based approximation
Published in International Journal of Electronics, 2023
Suman Yadav, Manjeet Kumar, Richa Yadav, Ashwni Kumar
Digital filters have been widely used in various areas such as image processing (Andrews et al., 2013), communication systems (Bolea et al., 2014), biomedical signal processing (Kumar et al., 2019; Kumar, Komaragiri, Kumar et al., 2018a, 2018b), speech synthesis and analysis (Airaksinen et al., 2014) and wireless communication (Li et al., 2012) and many more. They are basically required to extract useful information from a signal, to enhance the quality of a signal by removing noise and to separate two signals for analysis and estimation. Among all the design techniques which are available in literature for digital FIR filters, Park-McClellan (PM; McClellan & Parks, 2005) is considered as a benchmark technique. Because it provides good control over critical frequencies and a higher attenuation in stop band. But it is rarely used to construct FIR filter for its complicated implementation.
Design and Implementation of Robust Low Power ECG Pre-processing Module
Published in IETE Journal of Research, 2022
Kirti Tripathi, Harsh Sohal, Shruti Jain
Biomedical signal pre-processing plays an important role in medical instrumentation to enhance the quality of signal and eliminate undesired components. Electrocardiogram (ECG), biomedical signal, is also contaminated with undesired signal that degrade the useful information [1]. In this article, the prime focus is on robust hardware implementation of ECG pre-processing block using filtering technique. Filtering is an important step in the biomedical measurements and signal processing techniques. Analog to Digital Converter (ADC), Processing unit (PU) and Digital to Analog Converter (DAC) [1] comprises the blocks of digital filter [2,3]. The PU helps in filter designing by executing the complex calculation of adders and multipliers. There are various applications which utilized the characteristics of digital filters to enhance the performance of their output likewise radio communication, audio communication, biomedical signal processing and speech processing. Among them, biomedical applications emerged as one of the leading area from past few years. Figure 1 illustrates the comparison of different PU’s. The popular PU encompasses Microcontroller Unit (MCU), Digital Signal Processor (DSP), and Field Programmable Gate Array (FPGA). These processing units help to perform complex calculations for filter design. Nowadays, FPGA based processing units are preferred due to its remarkable performance that includes higher re-programmability, speed, architecture flexibility and it also acquire less execution time to process a unit with low power consumption.