Showing papers on "Filter (video) published in 1982"

Electronically Tunable Microwave Bandpass Filters

Abstract: Combline filters with novel input and output coupling networks which enable broad-band tuning to be achieved with minimum degradation in passband performance are discussed Explicit design formulas for these filters are presented Computer analysis of varactor tuned combine bandpass filters including the small signal varactor equivalent circuit is presented enabling filter performance to be easily evaluated The design and experimental performance of a varactor tuned combline filter, realized in suspended substrate stripline is described This filter toned from 32 GHz to 49 GHz exhibited low passband insertion loss and its performance was is close agreement with theoretical expectations

A family of differential NMOS analog circuits for a PCM codec filter chip

Abstract: A new NMOS PCM codec filter uses low-noise fully differential circuits to achieve supply rejection of 36 dB and idle channel noise of 6 dB/SUB rnc0/. The die size is 24 mm/SUP 2/ and the active standby power is 150 mW/5 mW.

Light utilization in optical correlators

Abstract: An analysis is made of the overall light efficiency in a coherent optical correlator. The results are applied to a matched filter and an inverse filter. Kogelnik's coupled wave theory is applied to analyze the diffraction efficiency of a filter recorded on a high-efficiency phase medium such as dichromated gelatin. Experimental results are presented for a matched filter and out-of-focus spatial filter, and the former is compared to the theory with good agreement.

Recursive adaptive filter design using an adaptive genetic algorithm

Abstract: An adaptive genetic algorithm for determining the optimum filter coefficients in a recursive adaptive filter is presented. The algorithm does not use gradient techniques and thus is appropriate for use in problems where the function to be optimized is non-unimodal or non-quadratic, such as the mean-squared error surface in a recursive adaptive filter. The mechanisms of the algorithm are inspired by adaptive processes observed in nature. After an initial set of possible filters is randomly selected, each filter is mapped to a binary string representation. Selected bit strings are then transformed using the operations of crossover and mutation to build new "generations" of filters. The probability of selecting a particular bit string to modify and/or replicate for the next "generation" is inversely proportional to its estimated mean-squared error value. Hence, the process not only examines new filter coefficient values, but also retains the advances made in previous "generations". Computer simulations of the algorithm's performance on unimodal and bimodal error surfaces are presented.

Process and apparatus for sealing a plurality of filter elements

Abstract: The present invention relates to a process and apparatus for making sealed filter units which include a plurality of filter elements. The apparatus includes a lower mold half for supporting a filter element support and a retractable locater member. The retractable locater member includes a reduced cross-sectional notched portion which projects above the lower mold half. When retracted into the lower mold half, the notched portion in conjunction with the upper and lower mold halves forms a cavity along the outer and upper peripheral edges of the filter elements and support. A thermoplastic material is injected into this cavity to capture the filter elements to the filter element support.

Reappraisal of arrays of concentric annuli as superresolving filters.

Abstract: The superresolving filter design of Toraldo di Francia [ Atti. Fond. Giorgio Ronchi7, 366 ( 1952)], which consists of an array of concentric annuli of finite width, is studied. Such a filter compares favorably with other superresolving filter designs while being considerably more simple to fabricate. In particular, for given input energy, the intensity at the focal point is usually greater than for optimized filter designs. The manufacturing tolerances of such a filter are discussed.

Arterial blood filter with improved gas venting

Abstract: A novel liquid filter of the "outside-in" type is disclosed, comprising a hollow tubular housing, a concentrically disposed perforated tubular core surrounded by a cylindrical filter element and communicating with a liquid outlet in the bottom wall of the housing, and a filter element cap covering the upper ends of the perforated core and filter element. A gas vent is located at the highest point in the top wall of the housing, which is at the center of the top wall. The liquid inlet and filter element cap are designed to provide for establishment of a stable swirling flow outside the filter element and above the filter element cap. An improved means of bonding upper and lower cup-like portions together to form a hollow tubular housing with high resistance to rupture under pressure is also disclosed. The filter of the invention is particularly suited for use in extracorporeal blood flow circuits, most particularly as an arterial blood filter located downstream from a blood oxygenator.

Finite word length FIR filter design using integer programming over a discrete coefficient space

Abstract: It is demonstrated that the improvement achieved by using integer programming over simple coefficient rounding in the design of finite impulse response (FIR) filters with discrete coefficients is most significant when the discrete coefficient space is the powers-of-two space or when a specification is to be met with a given coefficient word length by increasing the filter length. Both minimax and least square error criteria are considered.

Designing a Bloom filter for differential file access

Abstract: The use of a differential file for a database update can yield integrity and performance benefits, but it can also present problems in providing current data to subsequent accessing transactions. A mechanism known as a Bloom filter can solve these problems by preventing most unnecessary searches of the differential file. Here, the design process for a Bloom filter for an on-line student database is described, and it is shown that a very effective filter can be constructed with a modest expenditure of system resources.

Exhaust gas cleaning apparatus

Abstract: In an exhaust gas cleaning apparatus a ceramic heating resistor has a lattice-shaped exhaust gas passage and is formed by extrusion. The ceramic heating resistor is fixed closely to the upper stream side of a filter which catches particulates contained in exhaust gas. This heating resistor is divided into a plurality of sections so that heating current is successively supplied to the divided sections.

Diffractive subtractive color filter responsive to angle of incidence of polychromatic illuminating light

Abstract: A variable index-of-refraction optical medium of certain minimum thickness and periodicity with respect to the wavelength of incident light--if it meets certain specified constraints with respect to (1) relative indices-of-refraction of both its internal structure and that of its surroundings and (2) relative values of incident wavelength to periodicity and the relative indices-of-refraction--operates to produce both angularly-dependent subtractive-color filter reflection spectra and subtractive-color filter transmission spectra in accordance with its physical parameters. Such filters are suitable for use as authenticating devices for sheet-material authenticated items.

System and method for predicting ventricular tachycardia with a gain controlled high pass filter

Abstract: A system for predicting ventricular tachycardia from electrocardiograph input waveforms. A first means generates a signal representative of the input waveforms exceeding a preselected level. A second filter means has its gain controlled responsive to the first means output signal, and provides an output responsive to said input waveforms. Ventricular tachycardia is then predicted responsive to the second filter means output. In one embodiment, the input waveforms are digitized prior to processing by the first and second means. In another embodiment, the input waveforms are signal averaged prior to processing by the first and second means.

Sterile solution delivery and venting devices

Abstract: Sterile solution delivery and venting devices for use with multi-dose sterile solution packages are disclosed. The devices include a positive acting, normally closed check valve which opens to express solution from the package when squeezing pressure is applied and which automatically closes when the pressure is released. A hydrophobic filter is included to sterilize the replacement air which enters the package upon release of the squeezing pressure.

Electric filter with movable belt electrode

Abstract: A method and apparatus for removing airborne contaminants entrained in a gas or airstream includes an electric filter characterized by a movable endless belt electrode, a grounded electrode, and a filter medium sandwiched therebetween. Inclusion of the movable, endless belt electrode provides the driving force for advancing the filter medium through the filter, and reduces frictional drag on the filter medium, thereby permitting a wide choice of filter medium materials. Additionally, the belt electrode includes a plurality of pleats in order to provide maximum surface area on which to collect airborne contaminants.

Mse variable step adaptive filter

Abstract: A very rapidly converging adaptive filter which uses a variable scale factor for each weight of the filter. The value of the variable scale factor is chosen for each iteration and is based upon the sign changes of the incremental weight change. The variable scale factor exhibits large values when no sign changes occur and smaller values when sign changes occur. The new filter provides considerable improvement in increase of convergence rate and decrease in residual errors even in the presence of heavy noise while requiring only a modest increase in hardware.

Color sensing device

Abstract: A color sensing device comprising four photo-electric transducers formed on a semiconductor substrate, an interference filter provided on the light receiving face of each transducer, a colored filter for selecting a specified transmission band of the interference filter, and three electrodes for delivering electric signals from the transducers individually, one of the electrodes being provided for two of the transducers in common. The transducers each have the area of its light receiving face so determined as to exhibit spectral sensitivity characteristics matching the color matching function of the CIE (Commission Internationale de l'Eclairage) XYZ colorimetric system.

Air conditioning apparatus

Abstract: Air conditioning apparatus comprises a chiller 10, a heat exchanger 11 connected across the outputs of the chiller 10 and disposed in an air duct 12, an air cooling tower circuit, generally indicated at 13, for cooling the chiller 10 and connectable by pipes 14 and 15 and valves 16 and 17 to supply cooling liquid to the heat exchanger 11. A filter 21 is located in the system to clean water flowing from the air cooling tower 20. Provision is made for back washing the filter 21. Various constructions of the filter 21 and its filter elements are described.

Mid-infrared filters using conducting elements /

Abstract: This paper presents measured data on mid-infrared filters using conducting elements based on a simple first-order design philosophy. To the best of our knowledge, the filter center frequencies are at least a factor of 10 higher than any previously reported. The use of conducting elements adds an additional degree of freedom, which may be exploited to obtain filter characteristics superior to simple multilayer dielectric filters.

Surgical suction tip with filter

Abstract: A surgical suction tip includes an outer housing and an inner removable filter device. The housing includes a suction opening at one end and a filter receiving handle formed as a sleeve at the other end; the inner removable filter device is connected in the filter receiving handle by a quick connect-disconnect means; the housing tapers so as to increase in size from its suction opening to the filter device. A seal is located between the housing and filter device.

System and method for predicting ventricular tachycardia by adaptive high pass filter

Abstract: A ventricular tachycardia (VT) prediction system for use with an ECG input having cyclical characteristics. The ECG input is periodically sampled during each of a plurality of ECG cycles, and signals representative of the ECG input for each corresponding sample time are stored. A high pass filter adaptively filters the signals for each ECG cycle, so as to provide a filter output systematically related to the high frequency content of the ECG input. The adaptive filter produces segments which are uninfluenced by other samples so as to negate ringing. A reference signal is provided for VT prediction. The filter output is compared to the reference signal, and the prediction of ventricular tachycardia is indicated responsive to the comparison. In one embodiment the samples are averaged for a plurality of ECG cycles prior to generating the filter output. In another embodiment, the system determines the duration of the QRS portion of the ECG cycles prior to generating the filter output. In another embodiment, the system determines the duration of the QRS portion of the ECG signal, provides a second reference signal for VT prediction, and compares the determined duration to the second reference signal. A prediction of ventricular tachycardia is indicated responsive to the second comparison.

System and method for predicting ventricular tachycardia by derivative analysis

Abstract: A system for predicting ventricular tachycardia from electrocardiograph input waveforms. A high pass filter provides an output responsive to the input waveforms. A time derivative of the filter output is generated to produce waveforms which can be compared to a standard. In one embodiment, the input waveforms are digitized prior to processing by the filter means. In another embodiment, digitized input waveforms are signal averaged prior to processing by the filter. The filter can be a finite impulse response filter of an infinite impulse response filter. In an alternate embodiment, a ventricular tachycardia prediction system for use with ECG waveforms having cyclical characteristics is disclosed. The ECG waveforms are periodically sampled during each of a plurality ECG cycles. A filter unidirectionally filters the signals for each ECG cycle so as to provide a filter output systematically related to the high frequency content of the input. A reference signal is provided for ventricular tachycardia prediction. The filter output is compared to the reference signal, and a propensity for episodes of ventricular tachycardia is indicated responsive to the comparison.

General correlation of the initial collection efficiency of granular filter beds

Abstract: A general correlation for the prediction of the initial collection efficiency of granular filter beds is proposed. The correlation is based on the results obtained from trajectory calculation and the comparison between the numerical results and available experimental data. The correlation includes all the pertinent dimensionless groups and agrees with reported data within experimental accuracy.

Method and apparatus for measuring the depth of a tool in a borehole

Abstract: A high resolution method and apparatus for measuring the depth of a tool suspended from a cable inside a borehole are described. The tool includes accelerometers for measuring its acceleration and this measurement is combined with a cable depth measurement with which the amount of cable in the borehole is determined. A Kalman filter is employed to continually provide estimates of the velocity and depth of the tool from the accelerometer and cable depth measurements. A filter modifier alters operation of the filter during discontinuous motions of the tool such as when it is stuck and slips. A tool sticking detector senses when the tool is stuck and for how long to correspondingly modify the filter by forcing it to more strongly rely upon accelerometer measurements when the tool is stuck and gradually return to normal filter operation when the tool resumes movement after having been stuck.

Optimization of short digital linear filters for increased accuracy

Abstract: The accuracy of short length digital linear filter operators can be substantially increased if the sampling interval as well as the abscissa shift are properly adjusted. This may be done by a trial and error process of adjustment of these parameters until the error made by the filter operator, applied to a suitably chosen test function, is smallest. As an illustration of the application of this method, 7-, 11- and 19-point filters for the calculation of Schlumberger apparent resistivity from a known resistivity transform are designed. Errors with the new 7-point filter are seen to be less than those with a 19-point filter of conventional design. The errors with the new 19-point filter are two to three orders of magnitude smaller than those made by the conventional 19-point filter. The new method should provide digital linear operators that allow significant improvements in accuracy for comparable computation efforts, or substantial reduction in computation for comparable accuracy of results, or something of both.

Flush-back filter

Abstract: The invention relates to a flush-back filter, in particular for the filtration of oil, having filter elements (filter cartridges) arranged in a circle in the filter housing and a flushing member rotatable around the filter axis for the back-flushing of filter elements with the filtrate. According to the invention said filter elements are arranged on at least two concentric circles within the interior of said filter housing whereby said filter elements lying on one circle are located in the gaps between said filter elements lying on the other circle. For back-flushing of said filter elements horizontal on the concentric circle, there is a common flushing member below and with a small radial dimension, which is driven by a rotary drive. The back-flush filter has at least fourteen to twenty filter elements. Furthermore, a safety filter is arranged on the interior of the filter housing, which encircles said filter elements.

Pipette and filter combination

Abstract: A pipette having a liquid receiving hollow generally encompassed by deformable side walls, the pipette further has a tapered liquid outlet extending from one end of the hollow and a liquid inlet on the other end of the hollow within which is located a semi-permeable filter.

Filter testing apparatus and method

Abstract: A filter testing apparatus and method are provided wherein a challenge aerosol or the like is introduced upstream of the filter, and the downstream face of the filter is scanned with an air sampling probe to detect for the presence of leaking aerosol. The apparatus comprises a generally rectangular frame, and an air sampling probe which is mounted to the frame so as to be movable in a predetermined pattern wherein the entire face of an adjacent filter is scanned. The assembly may be removably mounted in a filter housing immediately downstream of the filter, or mounted on a framework downstream of a bank of several filters. In the latter instance, the assembly is sequentially indexed to a position alignment with each filter, and an upstream aerosol dispersion assembly is also provided which is correspondingly indexed across the filter bank. The rate of leaking challenge aerosol is continuously plotted on a moving sheet of paper to thereby permit the magnitude of a leak and its location on the face of the filter to be readily determined.

The truncated second-order nonlinear filter revisited

Abstract: By rederiving the truncated second-order nonlinear filter, it is shown that the original derivations of this filter contain errors, or at least illogical approximations. The so-called modified truncated second-order nonlinear filter is, furthermore, shown to be the correct form of this filter provided a small correction is made in the discrete-time case.

Implementation of active distributed RC anti-aliasing/smoothing filters

Abstract: The design of an active distributed RC filter is described for use as an anti-aliasing/smoothing filter in a PCM channel bank filter. A new filter configuration (known as a Rauch filter) has been chosen which uses the op amp in inverting configuration with a zero common mode signal and thus results in improved high-frequency attenuation characteristics along with good power supply rejection. A conventional Sallen and Key configuration with distributed RC elements is also discussed.