Pole Filter Research Articles

Application of magnetic method for mapping buried structures around archaeological site of Masjid Tuha Indrapuri

Magnetic gradiometer survey has been conducted on the yard of the archaeological site of Masjid Tuha Indrapuri, Aceh Besar Regency, Aceh Province. The site is one of the oldest mosques erected during the Aceh Sultanate period. Magnetic method was applied for mapping archaeological structures buried beneath the surface. Total magnetic field data were measured using Proton Precession Magnetometer with grid spacing of 2 meters between stations covering the entire area of the site. Diurnal and international geomagnetic reference field data were corrected to the measured data in order to calculate total magnetic field anomalies that were influenced by the buried magnetic objects. The total magnetic field anomalies distribution shows two elongated structures with U-shaped patterns surrounding the mosque. The patterns are also revealed in reduction to the pole and derivative vertical filters of the total field anomaly data. The anomaly patterns are considered a response from the rest of the buried fences that were built around the mosque in the past.

Waveguide Filters With Central-Post Resonators

In this letter, a class of rectangular waveguide filters with central-post resonators is introduced. By introducing a central post in an oversized rectangular cavity, the resonant frequency of TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">301</sub> -mode can be brought close to that of TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">201</sub> -mode. The two resonant modes are coupled to adjacent fundamental mode resonators by inductive irises. A doublet coupling topology can be used to model the physical configuration, and flexible filter responses with finite-position transmission zeros (TZs) can be realized. Four 4-pole filters with different TZ positions are designed and simulated. A seven-pole filter with two cascaded central-post resonators is fabricated and measured. In the seven-pole filter, each central-post resonator independently controls one TZ on the lower side and very close to the passband. The measurement results of the seven-pole filter agree with the simulated counterparts very well, thus validating this filter design technique.

Development of a High-Speed, Permanent Magnet, SiC-Based Drive With Integrated Input Filters

AC Input filters in high speed drives are generally large and can even exceed the mass of the motor. This article firstly seeks to reduce the volume and overall mass of the drive through integrating the input inductors with the magnetic circuit of the machine. The magnetic circuits are shared without cross-coupling through careful choice of the filter and motor pole numbers. Finite Element Analysis (FEA) is used to check that normal operation of the base PM machine is not affected by the integration and a demonstrator drive is built. Compared with discrete AC filters, the integration of the LCL filter inductors has given a very large volume reduction of 87.6%, producing a much more compact envelope than with the conventional filter inductors. Through a holistic approach to a combination of electrical, mechanical and thermal aspects of the drive system, the integrated drive exhibits significant mass and volume advantages over conventional discrete motor drives. Two major technical issues related to the power electronics development of the IMD are presented in the paper: investigation of a bus bar solution to manage a large number of winding terminals introduced from integrated LCL filters, and a compact SiC device based power electronics design.

Influence of Blade Flexibility on the Dynamic Response Simulation of a Turbomolecular Pump on Magnetic Bearings

Abstract This paper proposes the simulation of a complete mechanical model of a turbomolecular pump rotor, including rotor and blades flexibility, suspended by controlled active magnetic bearings. The mechanical model is composed of an eight stage blisk, attached to a shaft. Magnetic forces are linearized by the first-order Taylor expansion around a given point. Including blades and rotor flexibility makes the mechanical system asymmetric, so the equations of motion for the coupled system have periodic terms. A modal controller was designed to control rigid body modes, since the number of sensors is limited and no state observer is implemented. PID controllers are used for low frequency modes combined with the second order filters to damp high frequency modes. First of all, stability analysis was carried out for the axisymmetric case. Second, blades flexibility was included. Forced response of the whole system to an impulsive force was studied. Divergent responses for the system in rotation were obtained as a second order filter pole possibly interacting with blades modes. Taking the second order filters off the control loop allowed the system to be stable. These results show that the analysis method developed here is efficient to evaluate the performance of a controller in closed loop with the complete flexible system. This method may be used in industrial design processes as computation times for the complete system are very short.

Quasi-Reflectionless Microstrip Bandpass Filters With Improved Passband Flatness and Out-of-Band Rejection

High-order quasi-reflectionless bandpass filters with improved passband flatness and good impedance matching both in-band and out-of-band are proposed in this work. The proposed design consists of conventional coupled-lines bandpass sections loaded with the presented absorptive stubs at the input and output. Analysis shows that the absorptive stub is equivalent to a 2-pole bandstop filter. Compared to the prior art, the higher-order nature of the presented absorptive stub enables a flatter passband and better out-of-band rejection. The overall filter stopband attenuation can be readily improved by increasing the number of coupled-lines sections without altering the passband responses. Furthermore, cross-coupling between the two absorptive stubs can be used to improve the out-of-band rejection by introducing two transmission zeros without affecting the absorption characteristics. The proposed design concepts are experimentally validated by the design and fabrication of a set of 2.4-GHz 1-, 2-, and 3-pole microstrip quasi-reflectionless bandpass filters. Measured frequency responses of these filters closely match those of the simulation.

Vowel Onset Point Based Screening of Misarticulated Stops in Cleft Lip and Palate Speech

The presence of velopharyngeal dysfunction, dental occlusion, and mislearned articulation in individuals with cleft lip and palate (CLP) results in the production of misarticulated stop consonants. The present work considers vowel onset points (VOPs) as the anchor points, around which the consonant-vowel (CV) transition regions are segmented to analyze the difference between normal and misarticulated stops. VOPs are located using an epoch-synchronously computed feature called maximum weighted inner product. Spectro-temporal dynamics of CV transitions anchored around VOP are analyzed using two-dimensional discrete cosine transform (2D-DCT) coefficients, where 2D-DCT coefficients are derived from single pole filter (SPF) based time-frequency representation. The SPF-based 2D-DCT coefficients are used to train a support vector machine for the classification of normal and misarticulated stops, where the class of misarticulated stops includes weak, nasalized, palatal, velar, pharyngeal, glottal, and devoicing errors produced by CLP speakers. The performance of the proposed VOP detection algorithm is evaluated on a database containing CV units of normal and misarticulated stops, and the results are compared with the state-of-the-art VOP detection methods. The classification results obtained for the proposed SPF-based 2D-DCT coefficients are compared with the short-time Fourier transform-based 2D-DCT coefficients and Mel-frequency cepstral coefficients. Further, the performance of the proposed system is compared with the hidden Markov model-based goodness of pronunciation approach.

Tunable SIW Bandpass Filters With Improved Upper Stopband Performance

This brief propose the design and measurement of tunable, highly selective and wide-stopband microwave filters using substrate integrated waveguide (SIW) technology. A two pole filter is designed using optimized cavity parameters. Two higher order (4-pole) filters are designed by connecting two cavities vertically and horizontally through coupling slots. In this way, four poles are achieved in two cavities, in which the proposed filter produces $2\times \text{N}$ poles in N cavities. A varactor diode is employed in both configurations to make the filters tunable. The proposed filters have wide upper stopband performance [20 dB up to $4.8f_{1}$ (Filter 1) and 20 dB up to $4.2f_{1}$ (Filter 2)], lower insertion losses [0.2-1.1 dB (Filter 1) and 0.2-1.5 dB (Filter 2)] and good tunability ranges [2.7–3.4 GHz (Filter 1) and 3.1–3.9 GHz (Filter 2)]. In order to validate the proposed design, a prototype is fabricated on RT/duroid 5870 substrate and measured. The simulated results accord closely with the measured results.

A structure evolution-based design for stable IIR digital filters using AMECoDEs algorithm

This paper proposes a subsystem-based structure evolution algorithm for stable IIR digital filter design. The method designs the IIR digital filter through optimizing the filter structure. A filter structure is defined as the connection of the subsystems. A subsystem is a 2-order IIR digital structure with uncertain parameters. Subsystems are randomly connected with the constraints of no feedback branches between subsystems. The subsystem’s parameters and the connections between subsystems are optimized by evolutionary algorithms. An adaptive multiple-elites-guided composite differential evolution algorithm (AMECoDEs) is used to optimize this problem. Four classic types of filters, lowpass, highpass, bandpass and bandstop filters are designed. Five state-of-the-art evolutionary algorithms are compared. The simulation results show that AMECoDEs holds the first place on comprehensive performance and convergence rate. At the same time, the poles of filters all reside within the unit circle, which validates the stability of the IIR digital filters.

A mathematical method to realize complex poles in a high‐order passive switched‐capacitor filter

SummaryA high‐order discrete‐time IIR low‐pass with complex poles using charge sampling is presented in a single‐stage structure by using a mathematical strategy. In comparison with the analog complex‐poles Gm‐C filters, the proposed filter consumes lower power and has good linearity, and all of the tunings are implemented only by capacitor sizes. The proposed filter is a seventh‐order Butterworth, but this method can be generalized to implement other complex pole filters like Tchebyshev and Elliptic. Post‐layout simulation results in 130‐nm complementary metal‐oxide‐semiconductor (CMOS) show an IIP3 of +18 dBm and a noise figure of 5 dB. The filter has a rejection of more than 110 dB in its stop band and consumes 1.5 mW with a 1.6‐V supply voltage, and circuit occupies an about 0.12 mm2 of silicon.

Detection of Nasalized Voiced Stops in Cleft Palate Speech Using Epoch-Synchronous Features

The presence of velopharyngeal dysfunction in individuals with cleft palate CP nasalizes the voiced stops. Due to this, voiced stops /b/, /d/, /g/ tend to be perceive like nasal consonants /m/, /n/, /ng/. In this work, a novel algorithm is proposed for the detection of nasalized voiced stops in CP speech using epoch-synchronous features. Speech regions corresponding to consonant and consonant-vowel transitions are segmented using the knowledge of glottal activity, syllable nucleus, low-frequency spectral dominance, and vowel onset point. The segmented regions are epoch-synchronously processed to analyze the spectral, spectro-temporal, excitation source, and periodicity characteristics of normal and nasalized voiced stops. Spectral and spectro temporal features are computed using single pole filter based time-frequency representation. The amplitude of Hilbert envelope of linear prediction residual, measured around the epoch is used to analyze the effect of nasalization on excitation source. Comparison of speech frames of successive inter-epoch intervals is carried out to analyze the periodicity characteristics. The proposed features are used to develop a support vector machine classifier for the classification of normal and nasalized voiced stops. Segmentation accuracy for the proposed knowledge based method is found to be better than the hidden Markov model based force-alignment approach. The detection rate of nasalized voiced stops is found to be high for the proposed epoch synchronous features than the conventional Mel-frequency cepstral coefficients.

Transition between flat magnitude and flat group delay low pass recursive digital filters

Many a paper has been written on the characteristics of the continuous-time and discrete-time low-pass filters which are designed to have either maximally flat magnitude characteristics or maximally flat group delay responses. The polynomial (all pole) low pass recursive digital filters which are characterised by characterise the transition between a flat magnitude and flat group delay characteristics, named Transitional Butterworth Thiran (TBTh) recursive digital filters, is considered. The characteristics of the resulting filter change gradually from the characteristics of the well known Butterwort's filter to the characteristics of the Thiran's filter with the maximally flat group delay characteristic. Poles of the TBTh filter are obtained by interpolating between poles Butterworth and Thiran's filters by varying a parametar which controls the pole positions that enables a tradeoff between the steepness magnitude characteristic at passband edge and group delay deviation.

Design of microstrip bandpass filters based on stair-step patch resonator

ABSTRACTIn this research article, single pole bandpass filter using stair-step patch topology based on symmetrical and asymmetrical step impedance resonators has been designed for industrial, scientific and medical (ISM) band application. This filter has been modelled by Microwave Office simulator using RT/Duroid substrate constant of 10.8, the substrate thickness of 1.27 mm, loss tangent of 0.0023 and copper metallisation thickness of 0.035 mm. To enhance the stopband levels of filter response, two microstrip bandpass filters have been designed as two-pole configurations based on edge, and cross-coupled stair-step patch resonators using the same simulator tool and substrate specifications. The proposed filters have compact sizes of (0.311 x 0.233 for single pole filter, (0.578 x 0.24) for two-pole edge coupled filter and (0.566 x 0.234for two-pole cross-coupled filter designed at centre frequencies of 2.4, 2.46 and 2.41 GHz, respectively. These filters have interesting insertion loss and return loss magnitudes, narrow band frequency responses, second harmonic suppression and good stopband levels. Apart from ISM band applications, the proposed filters can be adopted in WLAN systems and Bluetooth applications for short-range devices. The experimental results for designed filters are of good consistency with the simulations.

Design and analysis of MISO bi-quad active filter

ABSTRACTIn this paper, a multiple-input single-output (MISO) voltage-mode bi-quad active filter using voltage differencing voltage transconductance amplifier (VDVTA) is designed and analysed. The filter can realize several functions such as low-pass (LP), high-pass (HP), band-pass (BP), band-reject (BR) and all-pass (AP). The proposed configuration employs three input voltages and generates a single output voltage. The filter characteristics, i.e., pole frequency (ωp) and quality factor (Q) are electronically tunable through the bias current of the VDVTA. The filter performance is analysed through sensitivity analysis in presence of parasitics as well as process, voltage and temperature fluctuations. The proposed design is implemented in a 45-nm CMOS technology and simulated using Virtuoso Analog Design Environment of Cadence.

Design of highly compact reconfigurable filters with tunable reactive loading

A compact and electronically tunable substrate integrated waveguide cavity resonator is presented in this work. The SIW cavity resonator is loaded symmetrically with stubs on the two sides which are terminated through varactors. By changing the capacitance along the loaded stubs the resonant frequency has been varied. Parametric analyses carried out in this work show a large potential tuning range along with the total resonator size of less than 3/4 λg. The resonator is created on a single layer printed circuit board with integrated biasing network. A two pole filter is realized using the tunable resonator and measured tuning bandwidth of 8.51% at center frequency of 2.55 GHz is demonstrated. The insertion loss is measured between 2.7 and 4.8 dB for the whole range and the return loss is less than 13.5 dB. The technique also allows the real-time fine tuning of coupling coefficient of the two resonators which can easily be extended to the realization of higher order filters. The proposed filter is an excellent candidate for miniaturized RF front-ends where tuning is essential for better spectrum control.

Dual-Band Bandpass Double Ground Plane Coaxial Resonators and Filters

This paper proposes a novel double ground plane coaxial resonator that allows to realize two independent coaxial cavity modes in reduced physical volume. This configuration of compact high performance filters is an enabler for multiband transmitter architectures using modern radio frequency data convertors. The proposed approach benefits from simple design and design flexibility. The benefit of the proposed approach is the ease of design and the design flexibility. The proposed filters provide the ability to control the frequency, the bandwidth, and the introduction of transmission zeros separately for each band. A number of designs are presented to demonstrate the operation principle and the performance characteristics of the proposed filters. A $2 \times 4$ pole filter has been manufactured and tested with very good obtained results.

An efficient hardware architecture for detection of vowel-like regions in speech signal

Vowel-like regions (VLRs) in a speech signal include vowel, semivowel and diphthong sound units. In the existing VLRs detection methods, front-end speech parameterization have been done by complex algorithms. Those approaches require more hardware and hence delay the process. To address this issue, a simple and robust signal processing approach and it's hardware architecture is proposed for discriminating VLRs in the speech signal. In the proposed approach, non-local slope difference (NSD) at each time instant is computed by processing the speech signal through a single pole filter. The NSD is then averaged over an analysis frame and non-linearly mapped using negative exponential to reduce the fluctuations present in the input speech signal. The non-linearly mapped averaged NSD (NL-ANSD) is used as the front-end feature for discriminating VLRs. The NL-ANSD exhibits significantly sharp transition at the starting and ending points of the VLRs. The regions wherein the proposed feature exhibits significant transition and attains lower magnitude for a considerable duration of time are hypothesized as the VLRs. The proposed approach is very simple and requires significantly less hardware when compared with the existing zero-frequency filtering (ZFF) based methods. On the other hand, the proposed approach outperforms the existing ZFF based approaches for the task of detecting VLRs in clean as well as noisy speech signals. The hardware architecture of the proposed approach is verified by implementing it on the Nexys video Artix − 7(XC7A200T − 1SBG484C) field-programmable gate array (FPGA) trainer board for multimedia applications using Xilinx system generator-2016.2.

Precision analysis with analytical bit‐width optimisation process for linear circuits with feedbacks

Finding the best possible word length to accuracy trade off seems to be an obvious design task. However, the literature and carful design reviews show that word lengths are often overestimated to put the data accuracy at the safe side. This study proposes a mathematical process to balance that trade off. It describes an analytical optimisation technique that considers every interconnection and it shows clear improvement with respect to published results. To allow reproducibility of their work, detailed procedures are provided. Implementation results are presented for different configurations of infinite impulse response filters. More, the impact of the proposed bit-width optimisation on the filter poles and zeros is provided to show the effectiveness of the proposed solution. Their solution provides overall improvement going up to 17% of the circuit's area with respect to existing methods. The proposed technique for uniform fractional bits allocation runs in a negligible time independently of the targeted accuracy.

Dual-band substrate integrated waveguide (SIW) band pass filter for scientific radar applications

In this paper, a dual-band substrate integrated waveguide filter is proposed for 45.5–52.5 GHz and 60–62.5 GHz band. Dual-band substrate integrated waveguide filter is a three pole filter and with multiple transmission zeros. The substrate integrated waveguide (SIW) is designed by inserting metallic vias along the side walls of the substrate with specific spacing and varying diameter. A parametric study by varying the vias geometry is presented with vias diameter as 0.10, 0.12 and 0.18 mm. The return loss and insertion loss of the proposed filter are better that 15 and 1.18 dB, respectively at 0.12 mm which is the improved result as compared when the vias diameter is 0.10 mm and 0.18 mm. The fractional bandwidth is 8.9 and 4.09% from 45.5 to 52.5 GHz and 60 to 62.5 GHz, respectively.

WR-3 Waveguide Bandpass Filters Fabricated Using High Precision CNC Machining and SU-8 Photoresist Technology

This paper presents two WR-3 band (220–325 GHz) filters, one fabricated in metal using high precision computer numerically controlled milling and the other made with metallized SU-8 photoresist technology. Both are based on three coupled resonators, and are designed for a 287.3–295.9-GHz passband, and a 30-dB rejection between 317.7 and 325.9 GHz. The first filter is an extracted pole filter coupled by irises, and is precision milled using the split-block approach. The second filter is composed of three silver-coated SU-8 layers, each 432 μm thick. The filter structures are specially chosen to take advantage of the fabrication processes. When fabrication tolerances are accounted for, very good agreement between measurements and simulations are obtained, with median passband insertion losses of 0.41 and 0.45 dB for the metal and SU-8 devices, respectively. These two filters are potential replacements of frequency selective surface filters used in heterodyne radiometers for unwanted sideband rejection.

Pengenal Gerakan dengan Joystick Akselerometer Menggunakan Filter Kalman

Human Machine Interaction keeps growing and developing, one of development is through gesture recognition that detects acceleration in a movement. This technology has been applied in joystick Wiimote and Wii-nunchuk by Nintendo that is widely used all over the world. Two main challenges in using accelerometer are to eliminate the noise of the sensor and to cancel the detected gravity acceleration when the joystick is tilted. The noise and gravity acceleration may influence the data reading and create error accumulation, respectively. This work proposes an implementation of Kalman Filter and also a simple technique to eliminate the influence of the gravity acceleration as a solution to solve above problems in using accelerometer of Wii-Nunchuk joystick in Board Arduino Mega 2560. The experimental results in motionless position show that the filter can reduce the gravity acceleration. We have to set the initial value of q and R parameters in the estimation of position, speed, and acceleration using Kalman filter. Once R is decided, the change of q will determine K k gain, and it will locate the poles of the observer that influence the stability and the estimation result. With R=0.00005 and q=1, the poles of Kalman filter are located in the unit circle so that the estimation is stable and appropriate with the data from the sensor and even cancel the noise.