Showing papers on "Prototype filter published in 1974"
TL;DR: It is shown that a second-order digital notch filter is uniquely characterized by two distinct parameters, the notch frequency and the 3-dB rejection bandwidth, as a result, such a filter can be realized using only two multipliers.
Abstract: It is shown that a second-order digital notch filter is uniquely characterized by two distinct parameters, the notch frequency and the 3-dB rejection bandwidth. As a result, such a filter can be realized using only two multipliers. Methods are outlined to design a notch filter for a prescribed notch frequency and a prescribed 3-dB rejection bandwidth, along with procedures for postdesign adjustment of these parameters. All two-multiplier, canonic and noncanonic, notch filter configurations are developed using the multiplier extraction approach. These networks are then compared with regard to the effect of internal multiplication roundoff errors. Results of computer simulation of the notch filter configurations are also included.
134 citations
TL;DR: The method is extended to recursive filters and a comparison is made with existing techniques of implementing digital filters for the needs in computation and storage hardware: a specific example of design underlines the reduction in computation speed achieved in practice through this method.
Abstract: Any digital filter can be decomposed into two basic subsets, an extrapolator the output of which is sampled at a frequency depending only on the filter bandwidth and an interpolator delivering the filtered signal at the imposed output sampling rate. Redundancy in extrapolator and interpolator is removed by introducing half-band nonrecursive filtering elements for which definition, performance figures and efficient implementation are supplied. They reduce significantly the necessary computation and storage at the cost of a slight group delay increase. A formula is given for the amount of multiplications to be carried out every second in a filter; it depends on the filter bandwidth, signal to distortion ratio, and input-output sampling rate. The method is extended to recursive filters and a comparison is made with existing techniques of implementing digital filters for the needs in computation and storage hardware: a specific example of design underlines the reduction in computation speed achieved in practice through this method, which brings digital filters in a most favorable position for their competition against analog filters in many application fields.
133 citations
TL;DR: An optimization algorithm is developed to minimize the p-error criterion under the constraint that the resulting filter be stable, and several examples are solved to illustrate the technique.
Abstract: In this paper a design technique for the two-dimensional filters is proposed. An optimization algorithm is developed to minimize the p-error criterion under the constraint that the resulting filter be stable. Design of one-dimensional filter may be considered as a special case to which the proposed algorithm is applicable. Several examples are solved to illustrate the technique.
108 citations
TL;DR: In this article, the synthesis of narrow-band pass waveguide filters having flat group delay and optimum-amplitude characteristics is described, which utilizes either single- or dual-mode waveguide cavities.
Abstract: The synthesis of narrow-bandpass waveguide filters having flat group delay and optimum-amplitude characteristics is described. The design utilizes either single- or dual-mode waveguide cavities. Experimental results for a 40-MHz-bandwidth filter centered at 4 GHz show excellent agreement with theory.
97 citations
TL;DR: In this paper, a technique for designing stable two-dimensional recursive filters whose magnitude response is approximately circularly symmetric is presented, which is achieved by cascading a number of elementary filters which are called rotated filters.
Abstract: The digital filtering of two-dimensional signals offers the many advantages characteristic of digital computers, such as flexibility and accuracy. Applications exist in the processing of images and geophysical data. A technique is presented for designing stable two-dimensional recursive filters whose magnitude response is approximately circularly symmetric. This is achieved by cascading a number of elementary filters which are called rotated filters because they are designed by rotating one-dimensional continuous filters and using the two-dimensional z-transform to obtain the corresponding digital filter. Stability of these filters is considered in detail and the results obtained are stated in two corollaries. In particular it is proved that rotated filters are stable if the angle of rotation is between 270° and 360°. Finally, methods of analysis and design of the shape, circular symmetry, and cutoff frequency of two-dimensional recursive filters are discussed.
93 citations
TL;DR: In this article, a comparison between linear phase, finite impulse response (FIR) digital filters and infinite impulse response digital filters which meet equivalent frequency domain specifications is made, for the most part, based on the number of multiplications per sample required in the usual realizations of these filters, i.e., the cascade form for IIR filters and the direct form for FIR filters.
Abstract: The purpose of this paper is to make comparisons between optimum, linear phase, finite impulse response (FIR) digital filters and infinite impulse response (IIR) digital filters which meet equivalent frequency domain specifications. The basis of comparison is, for the most part, the number of multiplications per sample required in the usual realizations of these filters — i.e., the cascade form for IIR filters, and the direct form for FIR filters. Comparisons are also made between group-delay equalized filters and linear phase FIR filters. Considerations dealing with finite word-length effects are discussed for both these filter types. A set of design charts is also presented for determining the minimum filter order required to meet given low-pass filter specifications for both digital and analog filters.
93 citations
TL;DR: In this article, a new design theory is presented based on a sparse capacitance matrix for the array of coupled lines that constitute the filter, as opposed to a sparse-inductance-matrix assumption in previous theories that is much harder to satisfy.
Abstract: Hairpin-line and hybrid hairpin-line/half-wave parallel-coupled-line filters are preferred filters for microstrip and TEM printed-circuit realizations. This class of filters offers small size and, in general, needs no ground connections for resonators. A new design theory is presented that is based on a sparse capacitance matrix for the array of coupled lines that constitute the filter, as opposed to a sparse-inductance-matrix assumption in previous theories that is much harder to satisfy. It is shown that to a good approximation, hairpin-line filters result from frequency-scaling half-wave parallel-coupled-line filters. Because of this; the bandwidth can be accurately predicted. Design procedures are given for Type-A filters, which are useful up to 20-percent bandwidth. A variety of hybrid hairpin-line/half-wave parallel-coupled-line filters is possible, and their design is explained. Numerical results for a number of designs and experimental results for a 5-percent bandwidth filter are included.
69 citations
TL;DR: In this paper, a general low-sensitivity multiloop feedback configuration for realizing higher order transfer functions is presented, which incorporates the desirable building block approach of cascade design, and the results demonstrate the low sensitivity performance of the structure which, for some designs is superior to that of the "leapfrog" (LF) configuration, especially over a wide-band of frequencies.
Abstract: A general, low-sensitivity multiloop feedback configuration for realizing higher order transfer functions is presented. A synthesis procedure, which incorporates the desirable building block approach of cascade design, is described. In particular, the paper is concerned with the realization of higher order narrow-band bandpass (BP) functions where either biquad or Tarmy-Ghausi (TG) networks are used as active blocks. A sensitivity expression, dependent explicitly on the individual active block Q's and loop gains, is derived and minimized. The results demonstrate the low-sensitivity performance of the structure which, for some designs is superior to that of the "leapfrog" (LF) configuration, especially over a wide-band of frequencies.
54 citations
TL;DR: It is shown that a second-order digital notch filter is uniquely characterized by two distinct parameters, the notch frequency and the 3-dB rejection bandwidth, as a result, such a filter can be realized using only two multipliers.
Abstract: It is shown that a second-order digital notch filter is uniquely characterized by two distinct parameters, the notch frequency and the 3-dB rejection bandwidth. As a result, such a filter can be realized using only two multipliers. Methods are outlined to design a notch filter for a prescribed notch frequency and a prescribed 3-dB rejection bandwidth, along with procedures for postdesign adjustment of these parameters. All two-multiplier, canonic and noncanonic, notch filter configurations are developed using the multiplier extraction approach. These networks are then compared with regard to the effect of internal multiplication roundoff errors. Results of computer simulation of the notch filter configurations are also included.
50 citations
TL;DR: In this paper, a bandpass filter and a second-order Butterworth low-pass filter have been suggested using only resistors and two operational amplifiers, and the circuits have low parameter sensitivities.
Abstract: The utilization of the operational amplifier pole in the design leads to filters with satisfactory high-frequency performance. The approach reduces the number of capacitors required leading to circuits suitable for integration. Circuit arrangements for a bandpass filter and a second-order Butterworth low-pass filter have been suggested using only resistors and two operational amplifiers. The circuits have low parameter sensitivities.
35 citations
TL;DR: In this article, the authors examine the theoretical and practical issues of designing multiband filters and present several strategies for choosing the input parameters for the McClellan et al. filter-design algorithm to yield reasonable filters which meet arbitrary specifications.
Abstract: Although much has been learned about the relationships between design parameters for finite impulse-response (FIR) low-pass digital filters, very little is known about the relationships between the parameters of multiband filters. Thus given a set of design specifications for a multiband FIR filter (e.g., filter band edge frequencies and desired ripples in each of the bands) it is difficult to choose a set of modified parameters which will yield an acceptable filter using a standard FIR design algorithm. By an acceptable filter we mean one with monotonic behavior of the frequency response in the DON'T-CARE or transition regions between bands and one providing at least the desired attenuation (or ripple) in each of the bands. In this paper, we examine the theoretical and practical issues of designing multiband filters and present several strategies for choosing the input parameters for the McClellan et al. filter-design algorithm to yield reasonable filters which meet arbitrary specifications.
TL;DR: This paper reviews and compares the four multiple-loop feedback techniques used to realize high-order narrow-band filters; namely: follow-the-leader feedback (FLF), primary resonator block (PRB), leap frog (LF), and modified leapfrog (MLF) techniques.
Abstract: This paper reviews and compares the four multiple-loop feedback techniques used to realize high-order narrow-band filters; namely: follow-the-leader feedback (FLF), primary resonator block (PRB), leapfrog (LF), and modified leapfrog (MLF) techniques. The comparison is based upon the following criteria: design ease and flexibility, sensitivity performance, insensitivity to design errors due to nonideal operational amplifiers, and tunability. In all comparisons the simple but highly sensitive cascade technique is used as a reference. Several examples are cited which indicate comparative trends in sensitivity performance. Finally the computer program used to realize minimum sensitivity FLF networks is described.
TL;DR: In this article, a quasi-optical bandpass filter for millimeter and submilliieter wavelengths and in the far infrared region is described, which consists of three or more wire-grid polarizers with quarter-wave spacings.
Abstract: A quasi-optical bandpass filter suitable for millimeter and submilliieter wavelengths and in the far infrared region is described. It consists of three or more wire-grid polarizers with quarter-wave spacings. The filter has the advantage over conventional quasi-optical filters, e.g., Fabry-Perot filters, that its bandwidth and the shape of its frequency response are adjustable. This is achieved by changing the angular orientations of the wires of the different polarizers. The filter requires the input electric field to be linearly polarized in a direction perpendicular to the wires of the first grid. The theory of operation is presented and design formulas for the filter are given, under the assumption that ideal wire-grid polarizers are employed. The effects of using realistic grids on the performance of the filter are dealt within another paper.
TL;DR: In this article, a new class of filters based on inhomogeneous coupled-line structures having large even-odd mode-velocity ratios was proposed, e.g., a single inhomogenous coupled line filter section with an equiripple, 3-peak stopband and passband response.
Abstract: Experimental and theoretical results are presented demonstrating some novel properties of a new class of filters based on inhomogeneous coupled-line structures having large even-odd mode-velocity ratios, e.g., a single inhomogeneous coupled-line filter section with an equiripple, 3-peak stopband and passband response.
TL;DR: In this paper, a number of reflecting elements, of either inductive or capacitative metal mesh, with accurately controlled spacings, have been used to construct interference filters for wavelengths between 50 and 1000 μm.
TL;DR: An extra degree of freedom becomes available in the design of s.a.w. bandpass filters using double electrodes if the electrodes are individually weighed as mentioned in this paper, which removes fundamental synthesis problems encountered with more conventional structures.
Abstract: An extra degree of freedom becomes available in the design of s.a.w. bandpass filters using double electrodes if the electrodes are individually weighed. This procedure also removes fundamental synthesis problems encountered with more conventional structures.
TL;DR: A method is presented which makes it possible to build filters that, in some respect, behave like N -path filters but without suffering from the well-known disadvantages associated with the implementation of these latter filters, namely, incomplete cancellation of unwanted sidebands and interference caused by carrier leakage.
Abstract: A method is presented which makes it possible to build filters that, in some respect, behave like N -path filters but without suffering from the well-known disadvantages associated with the implementation of these latter filters, namely, incomplete cancellation of unwanted sidebands and interference caused by carrier leakage In conventional N -path filters the output signal is formed by summing signals which have been processed by N distinct paths, each path containing an intermediate network between input and output modulators The method to be presented consists in using one single path completely in time division multiplex This way the generation of interfering sidebands is avoided and carrier leak occurs at frequencies where it causes no trouble A general output-to-input relationship is derived for the ideal case, and the result is given as a time-varying system function With the aid of an example the effect of nonideal behavior which is encountered with practical circuits is analyzed Some practical results are shown
TL;DR: Algorithms for moving average, recursive and “Fourier transform” low-pass linear digital filters are described, with reference being made to the methods of design.
Abstract: Algorithms for moving average, recursive and “Fourier transform” low-pass linear digital filters are described, with reference being made to the methods of design. The characteristics, including frequency, phase and impulse responses, of four specific filters are discussed in detail. In addition, some of the practical problems of programming these filters are considered. Factors such as execution times are evaluated in concluding which designs are most appropriate for filtering electrocardiograms.
TL;DR: A lowpass prototype network that represents a canonical realisation for symmetric coupled-resonator bandpass filters is presented and a synthesis procedure for the prototype is outlined.
Abstract: A lowpass prototype network that represents a canonical realisation for symmetric coupled-resonator bandpass filters is presented. A synthesis procedure for the prototype is outlined.
TL;DR: This paper describes an algorithm that is suitable for fast implementations of nonrecursive and recursive digital filters and the memory-speed tradeoff is flexible so that many hardware and software implementations are practical.
Abstract: This paper describes an algorithm that is suitable for fast implementations of nonrecursive and recursive digital filters. High speed is realized at the expense of memory; however, the memory-speed tradeoff is flexible so that many hardware and software implementations are practical. When memory is not limited, the time required to compute a filter output value is independent of the order of the filter.
TL;DR: In this paper, the authors proposed a new kind of filter, of the transitional type, whose characteristics lie between those of monotonic with maximum cutoff rate (Legendre) and linear phase (Thomson) filters.
Abstract: Among those filters which exhibit both a good frequency and transient behavior, we suggest a new kind of filter, of the transitional type, whose characteristics lie between those of monotonic with maximum cutoff rate (Legendre) and linear phase (Thomson) filters. Attenuation, group delay, and step responses are given. Characteristics curves for the design of a fifth-order transitional Legendre-Thomson (TLT) filter are also presented.
TL;DR: In this article, an approach for designing wave digital filters that is based on a suitable interpretation of the scattering parameters of a network is presented, which can be used for simulating analogue, doubly terminated, lossless ladder filters.
Abstract: The purpose of the letter is to outline an approach for designing wave digital filters that is based on a suitable interpretation of the scattering parameters of a network. The approach can be used for simulating analogue, doubly terminated, lossless ladder filters.
TL;DR: In this article, the maximally flat criterion is extended to the design of two-dimensional nonrecursive digital filters which approximate circularly symmetrical low-pass specifications, and the choice of the local conditions is crucial, in particular for what regards the monotonic behavior outside the axes.
Abstract: The maximally flat criterion is extended to the design of two-dimensional nonrecursive digital filters which approximate circularly symmetrical low-pass specifications. Straightforward generalization of the one-dimensional method does not completely specify the coefficient matrix of the filter. The additional degrees of freedom can be used to increase locally the order of flatness at the origin and/or at the Nyquist frequencies. The choice of the local conditions is crucial, in particular for what regards the monotonic behavior outside the axes. Concentration of the local conditions on the diagonal of the frequency plane gives a special class of filters which, besides the advantage of closed-form expressions for the coefficients, has a monotonically decreasing frequency response along any radius of the frequency plane.
TL;DR: In this paper, the effects of using realistic grids on the performance of the adjustable quasi-optical bandpass filter presented in Part I. The theory given here is in excellent agreement with measurements performed on a three-grid filter in the 50-75 GHz band.
Abstract: This paper investigates the effects of using realistic grids on the performance of the adjustable quasi-optical bandpass filter presented in Part I. The theory given here is in excellent agreement with measurements performed on a three-grid filter in the 50-75-GHz band.
TL;DR: Using integrated squared error as a fidelity criterion with the magnitude of the filter transfer function subject to a constraint, the optimum spatial filter is developed.
Abstract: Fourier-transform division filters are discussed. Using integrated squared error as a fidelity criterion with the magnitude of the filter transfer function subject to a constraint, the optimum spatial filter is developed. By consideration of the problem of image transformation, various methods for improving image reconstruction by altering image phase are discussed. The input-image phase and the desired output-image phase may be chosen to improve the performance of the filtering system. The problem is to shape the spectra of the input and the desired output. An algorithm, previously used for computing kinoforms, effectively determines an image phase that significantly improves the image reconstructed from the spatial filters.
TL;DR: In this article, a new class of monotonic passband low-pass filters, referred to as transitional Butterworth-Legendre (TBL) filters, is introduced.
Abstract: A new class of monotonic passband low-pass filters, referred to as transitional Butterworth-Legendre (TBL) filters, is introduced. The closed form expressions of the characteristic functions of these filters depending on one variable parameter q are derived by generalization of the results previously obtained for Legendre sharp cut-off monotonic filters. The parameter q, the values of which are restricted to non-negative integer values (q≤n) controls the number of flatness conditions in the magnitude response at the origin and enables a trade-off between the passband loss and the stopband attenuation of the resulting filters. The Legendre, Halpern and Butterworth filters are shown to be special cases of TBL filters. Only all-pole filter functions are discussed although the results can easily be extended so as to include low-pass filters with finite real frequency transmission zeros.
TL;DR: In this article, the problem of implementing a two-dimensional recursive filter as a one-dimensional time-invariant recursive filter is examined and the frequency response, stability, and storage requirements of the approximate filters are derived and illustrated.
Abstract: The problem of implementing a two-dimensional recursive filter as a one-dimensional recursive filter is examined. The results of the present paper show that the exact one-dimensional implementation of a planar recursive filter is a time-varying filter. However, planar filters may be approximated by one-dimensional time-invariant recursive filters. The frequency response, stability, and storage requirements of the approximate filters are derived and illustrated.
01 Dec 1974
TL;DR: In this article, a matched CCD bandpass transversal filter was proposed to replace conventional analog filter amplifiers in scanning sensors, and the measured out-of-band rejection was more than 50 db and the dynamic range was greater than 80 db with good linearity using single-phase clocking.
Abstract: CCD bandpass transversal filters using overlapping aluminum/polysilicon gate technology have been fabricated and tested. The measured out-of-band rejection was more than 50 db and the dynamic range was greater than 80 db with good linearity using single-phase clocking. This CCD filter performance has been extended to include the matched filter concept. Fifty tap CCD filters matched to complex signal and noise spectra have been fabricated and tested. These filters are intended to replace conventional analog filter amplifiers in scanning sensors. Test results confirm the substantial increase in signal-to-noise ratio (SNR) predicted. It was also confirmed that the filters remained matched for a range of scan rates (time-domain scaling) by suitably changing the CCD clock frequency and input pulse width. As noted for the bandpass filter, other parameters compare well with those typical of analog filter performance.
TL;DR: In this paper, an analytical procedure for designing a linear digital notch filter is presented, which is implemented by cascading three second-order filters so as to avoid instability which may arise from computer coefficient truncation.
Abstract: An analytical procedure for designing a linear digital notch filter is presented. The resultant filter is sixth-order and is implemented by cascading three second-order filters so as to avoid instability which may arise from computer coefficient truncation. The procedure outlined is straightforward, requires only simple algebraic steps, and gives filter parameter selection criteria for reducing the effects of computer coefficient truncation. Notch filters have utility in situations where a desired signal is corrupted by an additive sinusoidal pickup. One thus must process the noisy signal so as to remove the sinusoid without significantly distorting the desired signal.