Finite Impulse Response Research Articles

Recursive system identification method from binary input/output measurements

AbstractThis paper presents two online identification algorithms of finite impulse response (FIR) systems using binary measurements both on the input and on the output. These algorithms are based on the least mean square (LMS) technique and on the estimation of the correlation functions of the input and output from binary data. Note that the second algorithm is a simplified version of the first one in the case of a white noise on the input. The convergence and variance analyses are provided. A numerical example is given to demonstrate the effectiveness of the proposed algorithms.

ECG R-Wave Detection and Its Application in Left Ventricular Assist Device

Heart failure is one of the major diseases endangering human life. As a transitional support treatment before heart transplantation, the left ventricular assist device (LVAD) has significantly improved the quality of life and survival rate of patients with end-stage heart failure. In the automatic detection of electrocardiogram (ECG), the detection of QRS wave groups is the most critical aspect, which affects the correctness and accuracy of subsequent data analysis and processing. The paper used the data from the MIT-BIH database and the data collected from human ECG as the original number of samples for further processing. It processed the data through a high-order finite impulse response (FIR) low-pass filter and Shannon energy algorithm, and added the use of a high-order adaptive median filter algorithm on a field programmable gate array (FPGA) to minimize the noise of the processed real-time data. Finally, the tested ECG R-wave was used to drive the LVAD. After successful simulation by MATLAB and Modelsim software, the scheme of the real-time ECG signal controlling blood pump system was realized on the FPGA platform. The experiment showed that the method proposed could accurately extract the R-wave and control the LVAD to pump blood simultaneously.

Hybrid Protection of Digital FIR Filters

A digital finite impulse response (FIR) filter is a ubiquitous block in digital signal processing applications and its behavior is determined by its coefficients. To protect filter coefficients from an adversary, efficient obfuscation techniques have been proposed, either by hiding them behind decoys or replacing them by key bits. In this article, we initially introduce a query attack that can discover the secret key of such obfuscated FIR filters, which could not be broken by the existing prominent attacks. Then, we propose a first of its kind hybrid technique, including both hardware obfuscation and logic locking using a point function for the protection of parallel direct and transposed forms of digital FIR filters. Experimental results show that the hybrid protection technique can lead to FIR filters with higher security while maintaining the hardware complexity competitive or superior to those locked by prominent logic locking methods. It is also shown that the protected multiplier blocks and FIR filters are resilient to existing attacks. The results on different forms and realizations of FIR filters show that the parallel direct form FIR filter has a promising potential for a secure design.

Simulations on the effects of an optimized bowtie dipole antenna with an adaptive FIR filter

In the evolution of technology through the years, antennas are use in varying wireless systems have been in demand. Antennas play a great role in transmitting and receiving signals. As its application is heavily used in many days to day activities, it is important to create a cost-efficient and quick way to analyze its performance, characteristics, and relationship to different variables. As many radiation pattern acquisition devices are expensive, this simulation proposes a quick, reliable, and cost-friendly way to simulate 2D patterns in the E-plane and H-plane of a bowtie dipole antenna with an adaptive finite impulse response (FIR) filter. Through this study, the software MATLAB will be utilized to successfully simulate the radiation patterns of antennas with varying lengths. With the use of MATLAB toolboxes, the researchers aim to be able to compare different antenna lengths and determine the relationship and effect of it in the obtained 2D radiation pattern. If this method is successful various antenna applications may be implemented in the future with the use of 2D radiation pattern results.

Displacement reconstruction based on Kalman smoothing in multi-rate suspension health monitoring systems

Suspension displacements and wheel center accelerations are important signals for suspension health monitoring systems to improve vehicle reliability and safety. The current way to obtain these signals is to install sensors on vehicles to conduct direct measurements. Usually, displacements are sampled at a slower rate than accelerations due to technical or economic limitations in real scenarios. This paper introduces a method for displacement reconstruction with low-sampling-rate displacement and high-sampling-rate acceleration measurements by formulating the reconstruction problem as a state estimation problem. A state-space model is established by identifying two data-driven models: a time-series Auto-Regressive model and a Finite Impulse Response model. Then, Kalman smoothing is used to estimate the displacement. A series of experiments have been done to show that the estimates from Kalman smoother coincide with the measurements.

Design of a finite impulse response filter for rapid single-flux-quantum signal processors based on stochastic computing

Design of a finite impulse response filter for rapid single-flux-quantum signal processors based on stochastic computing

Transmissibility-Based Fault Detection for Robotic Applications With Time-Varying Parameters

This article investigates transmissibility operators for time-variant systems with bounded nonlinearities. Transmissibility operators are mathematical objects that characterize the relationship between two subsets of responses of an underlying system. The underlying system parameters and nonlinearities are assumed to be unknown. Time-domain transmissibility operators are independent of the system inputs and initial conditions. In this article, we propose an algorithm to identify time-varying transmissibilities using recursive least-squares and noncausal finite impulse response models. The identified transmissibilities are then used for fault detection in three different systems. The first system is an autonomous multirobotic system formulated to emulate connected autonomous vehicle platoons, where the varying parameters are the robot mass and the ground friction coefficient. The second system is a flexible structure with unknown excitation, where the variant parameter is the location of the excitation. Finally, the third system is a robotic manipulator that picks objects with different mass values.

A 24-kHz BW 90.5-dB SNDR 96-dB DR continuous-time delta-sigma modulator using FIR DAC feedback

This paper presents a single bit continuous time delta-sigma modulator (CTDSM) with finite impulse response (FIR) feedback DAC designed for audio applications. By using FIR feedback in the input stage, the linearity requirements of the first integrator are relaxed, and the clock jitter sensitivity is reduced, as seen in a multi-bit quantizers. The choppers, working in conjunction with the FIR DAC, effectively suppresses in-band aliasing noise generated by the chopper in the first integrator. A fast comparator serves as a single-bit quantizer, and the 9.2% TS loop delay eliminates the need for excess loop delay compensation in the modulator. Energy efficient integrators are implemented using the current-starved OTA. The CTDSM prototype was fabricated using a 180-nm CMOS process, achieving a 90.5 dB SNDR and 96 dB DR with a 24 kHz signal bandwidth. The power consumption is 210 μ W, corresponding to a Schreier figure-of-merit value of 171.1 dB.

IIR Cascaded-Resonator-Based Complex Filter Banks

The use of a filter bank of IIR filters for the spectral decomposition and analysis of signals has been popular for many years. As such, a new filter-bank resonator-based structure, representing an extremely hardware-efficient structure, has received a good deal of attention. Recently, multiple-resonator (MR)-based and general cascaded-resonator (CR)-based filters have been proposed. In comparison to single-resonator-based analyzers, analyzers with a higher multiplicity of resonators in the cascade provide lower side lobes and a higher attenuation in stopbands. In previous works, it was shown that the CR-based filter bank with infinite impulse response (IIR) filters, which is numerically more efficient than one with finite impulse response (FIR) filters, is suitable for dynamic harmonic analysis. This paper uses the same approach to design complex digital filter banks. In the previous case, the optimization task referred to the frequency responses of harmonic filters. In this work, the harmonic filters of the mother filter bank are reshaped so that the frequency response of the sum (or difference, depending on the parity of the number of resonators in the cascade) of two adjacent harmonic filters is optimized. This way, an online adaptive filter base can be obtained. The bandwidth of the filters in the designed filter bank can be simply changed online by adding or omitting the output signals of the corresponding harmonics of the mother filter.

Design and Implementation of High Speed Low Power Decimation Filter for Hearing AID Applications

This work is focused on designing and implementing a decimation filter specifically intended for use in hearing aid applications. The filter utilizes distributed arithmetic (DA) and is described in this brief. Our proposal involves the development of a reconfigurable finite impulse response (FIR) filter, which utilizes both offset binary code (OBC) and binary distributed arithmetic (DA) techniques. Additionally, we utilize canonic signed digit (CSD) representation to develop decimation filters, which include the CIC filter, half band filter, and corrector filter. In this work, we have implemented a decimation filter using Matlab Simulink. We have utilized Xilinx Vivado 19.2 to execute the FIR filters, binary DA filters, and OBC DA-based filters. Our focus is on implementing these filters using VLSI architecture, in order to achieve low power consumption, reduced latency, less area, and fast speed.

Informed sparsity-based blind filtering in the presence of second-order cyclostationary noise

This study investigates the potential to improve the fault detection capability of sparsity-based blind filtering. It optimizes a finite impulse response filter to maximize the sparsity of the squared envelope spectrum (SES) of vibration signals. However, the method is to be highly prone to fail optimization due to the immense number of non-fault-related second-order cyclostationary interferences. These interferences can skew the sparsity estimation of the SES and thus impair the sparsity-based blind filtering method. Even whitening or signal separation methods can fail to remove such cyclostationary components adequately. Hence, the technique is unlikely to function particularly on the signals measured on complex industrial machines. This paper extends the initial study introducing sparsity-based blind filtering in the literature. It proposes refining the filter optimization’s objective function by targeting narrow frequency bandwidths on the SES to avoid non-fault-related peaks. The narrow bandwidths are selected by exploiting the available engineering knowledge, such as an average shaft speed. The proof of concept is shown on simulated signals, and the performance tests are made on signals measured on an industrial rotating machine and a wind turbine gearbox. The study’s outcome demonstrates that targeting automatically selected narrow bandwidths bounded by shaft speed harmonics can significantly improve the detection capability of sparsity-based blind filtering.

High Performance FPGA Implementation of Single MAC Adaptive Filter for Independent Component Analysis

Blind source separation (BSS) is the process of extracting sources from mixed data without or with limited awareness of the sources. This paper uses field programmable gate array (FPGA) to create an effective version of the Blind source separation algorithm (ICA) with a single Multiply Accumulate (MAC) adaptive filter and to optimize it. Recently, space research has paid a lot of attention to this technique. We address this problem in two sections. The first approach is ICA, which seeks a linear revolution that can enhance the mutual independence of the mixture to distinguish the source signals from mixed signals. The second is a powerful flexible finite impulse response (FIR) filter construction that makes use of a MAC core and is adaptable. The adjustable coefficient filters have been used in the proposed study to determine the undiscovered system utilizing an optimal least mean square (LMS) technique. The filter tap under consideration in this paper includes 32 taps, and hardware description language (HDL) and FPGA devices were used to carry out the analysis and synthesis of it. When compared to the described architecture, the executed filter architecture uses 80% fewer resources and increases clock frequency by nearly five times, and speed is increased up to 32%.

A tunable microwave photonic filter based on hole-assisted graded-index few mode fiber with uniform differential modal group delay

A tunable delay-line microwave photonic filter (MPF) based on hole-assisted graded index few mode fiber (HGI-FMF) is proposed. The HGI-FMF is designed with low mode crosstalk, low nonlinear effect and multiple modal groups. In particular, the designed HGI-FMF shows uniform differential modal group delay (MGD) to form finite impulse response (FIR) MPF. The uniform differential MGD is tunable with wavelength, which results in tunable MPF response. The free spectrum range (FSR) of MPF is continuously tunable from 11.73 GHz down to 10.84 GHz with 120 m designed HGI-FMF as the optical source is tuned from 1530 nm up to 1630 nm. The main sidelobe suppression ratio (MSSR) of the 4-taps filter is larger than 9.93 dB, and the 3 dB bandwidth is around 2.62 GHz.

Matched-filter design to improve self-interference cancellation in full-duplex communication systems

A new method for capacity and spectral efficiency increases is a full-duplex (FD) communication, where sending and receiving are done simultaneously. Hence, severe interference leaked from the transmitter to the receiver, which can disrupt the system's operation completely. For interference reduction, the transceiver tries to estimate the interfering symbols to remove their effects. A typical method is to use the Hammerstein model. In this method, nonlinear power amplifier (PA) and multipath channel are modeled with a successive nonlinear system and a finite impulse response (FIR) filter. Then, the model parameters are adjusted, and interference symbols are estimated from the transmitted symbols. In the Hammerstein method, the interference symbols are estimated directly from the transmitted symbols. But practically, the transmitted symbols first pass through the pulse-shaping filter and become a signal. Then, this signal passes through the nonlinear PA and communication channel. Finally, the received signal is filtered by the matched filter (MF) at the receiver and converted to the symbols again. In this procedure, the amplifier and the communication channel affect the transmitted signal directly and distort transmitted symbols indirectly. Therefore, in the practical situation, when we consider the transmitter's pulse-shaping filter and the receiver's MF, the estimated symbols with the Hammerstein method are erroneous. To solve this problem, a new MF at the receiver is proposed and adjusted according to the interfering signal. We have shown that this method is far better than the Hammerstein method.

A learning trajectory planning for vibration suppression of industrial robot

PurposeThis paper aims to propose a learning exponential jerk trajectory planning to suppress the residual vibrations of industrial robots.Design/methodology/approachBased on finite impulse response filter technology, a step signal with a proper amplitude first passes through two linear filters and then performs exponential filter shaping to obtain an exponential jerk trajectory and cancel oscillation modal. An iterative learning strategy designed by gradient descent principle is used to adjust the parameters of exponential filter online and achieve the maximum vibration suppression effect.FindingsBy building a SCARA robot experiment platform, a series of contrast experiments are conducted. The results show that the proposed method can effectively suppress residual vibration compared to zero vibration shaper and zero vibration and derivative shaper.Originality/valueThe idea of the adopted iterative leaning strategy is simple and reduces the computing power of the controller. A cheap acceleration sensor is available because it just needs to measure vibration energy to feedback. Therefore, the proposed method can be applied to production practice.

Implementation of polyphase digital down converter for wireless applications

This paper briefs the hardware-efficient polyphase digital down converter (DDC), which reduces the input sampling frequency to 3.64 GHz and produces a complex output to meet the IEEE 802.11ah wireless network standard. The design comprises a polyphase mixer (PM) filter and a lowpass polyphase finite impulse response (PFIR) filter. The PM filter uses a cascaded integrator comb (CIC) decimation filter based on multiplexer technology to potentially process parallel input interfaces and considerably reduce the sampling rate. The time-sharing mechanism of the CIC filter performs an efficient hardware implementation. Again, the improved design technique of the PFIR filter can effectively increase the operating speed and optimize power consumption. The proposed design offers high flexibility due to programmable sampling rate factors that can support multistandard communication systems. In addition, the design includes the truncation mechanism to protect against overflow errors and the fixed-point data type in each filter node to minimize the area requirements. The presented polyphase DDC is tested using the field-programmable gate array (FPGA) platform targeting the Xilinx Kintex-7 device. According to experimental results, the described DDC significantly reduces the logical resources and power dissipation associated with earlier design structures. The functional verification is tested to ensure the validation of the suggested design.

Real-time propeller fault detection for multirotor drones based on vibration data analysis

This article presents a Fault Detection (FD) method to deal with propeller faults on multirotor drones in real-time. Several solutions have been proposed in the literature, however, they depend on additional sensors and/or dedicated hardware to deal with heavy computational complexity. So, they cannot be implemented in off-the-shelf commercial devices, i.e., without the aid of additional on-board sensors and/or extra computational power. The proposed method, instead, requires the on-board Inertial Measurement Unit (IMU) data only: by combining Finite Impulse Response (FIR), together with sparse classifiers, only a subset of the features is actually needed online and the FD is thus feasible in real-time.Design and tests are based on real flight data from a hexarotor, equipped with a conventional ArduPilot-based controller. The classification accuracy in testing is up to 93.37% (98.21%) with a binary tree (Linear Support Vector Machine (LSVM)). Moreover, the space and time complexity of the proposed method is low: on a PixHawk Cube flight controller, it requires less than 2% of the cycle time, and can then run in real-time. Finally, the proposed fault detection solution is model-free and it can be easily generalized to other multirotor vehicles.

Implementation of a secure wireless communication system using true random number generator for internet of things

This paper describes the design and implementation of an internet of thing (IoT)-based application that uses a true random number generator (TRNG) with an all digital phase locked loop (ADPLL) for secure wireless communication. Field programmable gate array (FPGA) boards were used on the transmitter and receiver sides and were interfaced with Esp8266 chips to wirelessly send and receive encrypted sensor data. The MQ-2 gas sensor and tracking sensor were connected to the FPGA board on the transmitter side, where data from the sensors was encrypted using the exclusive-OR (XOR) function and the TRNG architecture. The system can be controlled by users through a web browser served by the ThingSpeak cloud. The Artix-7 FPGA device is used to implement the proposed wireless communication system, for which design and synthesis were done using the Xilinx Vivado 2015.2 tool. The proposed system uses a low amount of power and is suitable for a standalone, highly secure TRNG-based IoT application. The National Institute of Standard and Testing (NIST SP 800-22) test showed that ADPLL with finite impulse response (FIR) filter-based TRNGs are better for encrypting IoT devices for secure wireless communication.

A New OFDM System for IIR Channels

In this paper, we propose a new orthogonal frequency division multiplexing (OFDM) system for an infinite impulse response (IIR) channel with the form of B(z)/A(z) for two polynomials A(z) and B(z). Different from the conventional OFDM transmission over a finite impulse response (FIR) channel, a guard interval of an OFDM symbol is added such that the corresponding part at receiver is the cyclic prefix (CP) of the received OFDM symbol. The guard interval and CP lengths are the same and not smaller than the orders of polynomials A(z) and B(z). The OFDM symbol without the guard interval is the same as the conventional OFDM symbol without the CP. At the receiver, the IIR channel is then converted to N intersymbol interference (ISI) free subchannels, where N is the number of subcarriers of an OFDM symbol.

Millimeter-Wave Receiver With Non-Uniform Time-Approximation Filter

This article presents a non-uniform (NU) time-approximation filter (TAF) technique for a wireless receiver (RX) to reject unwanted blockers. The proposed NU TAF leverages the alias-spreading property of NU sampling (NUS) and a TAF that approximates a finite impulse response (FIR) filter response in the time domain, achieving an overall flexible filter response with a higher attenuation factor. The filter response can be readily reconfigured by changing the NU sequence and/or the TAF waveform without adjusting the passive component value. In addition, a quad-switch gated integrator is proposed to significantly reduce the power consumption by sharing the current among the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{G} _m$</tex-math> </inline-formula> cells. Detailed theoretical analysis on NU-TAF operation and RX implementation considering circuit non-idealities are provided to explore the design tradeoffs of the proposed techniques. A proof-of-concept millimeter-wave RX is implemented in the 28-nm CMOS process. Thanks to the NU TAF, the RX prototype achieves <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt;$</tex-math> </inline-formula> 45-dB blocker rejection with a 33.7-GHz carrier frequency. The EVM measures <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 30.9 dB using a 100-MSymbol/s 64-QAM signal in the presence of a 10-dBc out-of-band (OOB) blocker.