Showing papers on "Filter (video) published in 1990"

Performance measures for correlation filters.

Abstract: Several performance criteria are described to enable a fair comparison among the various correlation filter designs: signal-to-noise ratio, peak sharpness, peak location, light efficiency, discriminability, and distortion invariance. The trade-offs resulting between some of these criteria are illustrated with the help of a new family of filters called fractional power filters (FPFs). The classical matched filter, phase-only filter (POF), and inverse filter are special cases of FPFs. Using examples, we show that the POF appears to provide a good compromise between noise tolerance and peak sharpness.

Removable vascular filter

Abstract: A vascular filter for capturing blood clots in the vascular system of a patient. The filter is adapted for removable installation through an entry site, and comprises a wire member, plus a filter member permanently attached to one end of the wire member. The filter member comprises a plurality of self supporting filter wires normally diverging outwardly from, and extending forwardly from, the one end of the wire member. The filter wires are capable of being pressed into generally parallel relation with the wire member for installation and removal thereof.

Multidelay block frequency domain adaptive filter

Abstract: A flexible multidelay block frequency domain (MDF) adaptive filter is presented. The distinctive feature of the MDF adaptive filter is to allow one to choose the size of an FFT tailored to the efficient use of the hardware, rather than the requirements of a specific application. The MDF adaptive filter also requires less memory and thus reduces the hardware requirements and cost. In performance, the MDF adaptive filter introduces smaller block delay and is faster, making it ideal for a time-varying application such as modeling an acoustic path in a teleconference room. This is achieved by using a smaller block size, updating the weight vectors more often, and reducing the total execution time of the adaptive process. The MDF adaptive filter compares favorably to other frequency-domain adaptive filters when its adaptation speed and misadjustment are tested in computer simulations. >

Development of the filtered‐U algorithm for active noise control

Abstract: The filtered‐X algorithm developed by Widrow and Burgess is an alternate form of the least‐mean‐square (LMS) algorithm for use when there are transfer functions in the auxiliary path following the adaptive filter. To ensure convergence of the algorithm, the input to the error correlators is filtered by a copy of these auxiliary path transfer functions. More recently, the author has presented a new approach to active noise control in the presence of acoustic feedback that uses an infinite impulse response (IIR) filter structure with an alternate form of the recursive least‐mean‐square (RLMS) algorithm. This algorithm may be described as a filtered‐U algorithm since it uses a copy of the auxiliary path transfer functions to filter the generalized input vector U to the error correlators of both the direct and recursive elements of the filter to ensure convergence. The relationship of the filtered‐U to the filtered‐X algorithm and other earlier concepts is discussed.

Design considerations for high-frequency continuous-time filters and implementation of an antialiasing filter for digital video

Abstract: An approach that has made possible the integration of video frequency continuous-time filters with wide dynamic range is discussed. The tuning scheme necessary to maintain the stable and accurate frequency response in the presence of temperature variations, process tolerance, and aging is described. Detailed design techniques specific to high-frequency operation are introduced to implement a 5-V, seventh-order elliptic analog magnitude filter for antialiasing in digital video applications. The filter, based on a G/sub m/-C technique, exhibits a dynamic range of 61 dB and dissipates a power of 75 mW. Ninety-two chips from various wafers and two different process runs were tested. Seventy-five percent of the fabricated chips were functional, and 63% of them met the commercial-grade specifications in spite of an error in the layout which forced the phase control circuitry to perform suboptimally. >

Portable filtration unit

Abstract: A portable vacuum and air filtration unit, comprising: a plurality of separately transportable modules and a means for locking the modules together during use, an air inlet located in one of the modules, a debris screen and a means for receiving debris stopped by the screen located in one of the modules, an electrostatic filter located in one of the modules, a bag filter assembly located in one of the modules, a HEPA filter assembly located in one of the modules, and a means for drawing a substantial volume of air through the inlet, screen, electrostatic filter, bag filter assembly and HEPA filter assembly.

Theory of two-dimensional multirate filter banks

Abstract: Results are presented on 2-D FIR (two-dimensional finite-impulse-response) filter banks for multirate applications. The theory is valid for all sampling lattices; conditions for alias-free and perfect signal reconstruction are derived. Synthesis structures for paraunitary and nonparaunitary polynomial matrices are derived, which yield perfect reconstruction filter banks. The degrees of freedom are given for these systems. Linear phase conditions are posed on the polyphase form of filter banks. which is used to derive a design structure for the restricted, but important, case of linear phase filter banks. >

Electrostatically actuatable light modulating device

Abstract: The electrostatically actuatable light modulator utilizes an opaque substrate plate patterned with an array of aperture cells, the cells comprised of physically positionable dielectric shutters and electrostatic actuators. With incorporation of a light source and a viewing screen, a projection display system is effected. Inclusion of a color filter array aligned with the aperture cells accomplishes a color display. The system is realized in terms of a silicon based manufacturing technology allowing fabrication of a high resolution capability in a physically small device which with the utilization of included magnification optics allows both large and small projection displays.

Insertion instrument for vena cava filter

Abstract: An improved insertion instrument for a vena cava filter is provided and iudes a filter retainer attached to the catheter for preventing accidental ejection of the filter and for enabling retraction of the filter into the carrier body at any time prior to complete ejection; a directional control mechanism attached to the plunger housing for allowing a user to guide the filter retainer through a vascular network; and a simplified plunger locking mechanism on the plunger for preventing premature ejection of the filter

Performance analysis of LMS adaptive prediction filters

Abstract: The conditions required to implement real-time adaptive prediction filters that provide nearly optimal performance in realistic input conditions are delineated. The effects of signal bandwidth, input signal-to-noise ratio (SNR), noise correlation, and noise nonstationarity are explicitly considered. Analytical modeling, Monte Carlo simulations and experimental results obtained using a hardware implementation are utilized to provide performance bounds for specified input conditions. It is shown that there is a nonlinear degradation in the signal processing gain as a function of the input SNR that results from the statistical properties of the adaptive filter weights. The stochastic properties of the filter weights ensure that the performance of the adaptive filter is bounded by that of the optimal matched filter for known stationary input conditions. >

Realization of current mode all-pass networks using a current conveyor

Abstract: Two novel networks are proposed for realizing a current-mode all-pass filter with high output impedance, using a single current conveyor (CC II) and four passive elements. The networks can be used in cascade without requiring an impedance-matching device. Even with a nonideal CC II, the networks can realize all-pass networks with slightly altered values of the gain and the center frequency. >

An ASIC for high-resolution capacitive microaccelerometers

Abstract: An ASIC (application specific integrated circuit) for high-resolution capacitive accelerometers using switched-capacitor techniques is presented The circuit, realized in a 3 μm CMOS process, is suited for the measurement of the differential capacitance of any capacitor bridge and features a maximum output noise density of −110 dB V/ ✓Hz The cut-off frequency of its first-order low-pass filter characteristic is determined by an external filter capacitor and the sampling rate

Percutaneously implanted filter in blood vessel - is made from biologically decomposable material and has hooks to engage walls of blood vessel

Abstract: The blood vessel filter is percutaneously implanted in the blood vessel by a catheter. The filter (10) is supported by a number of short rods (12) which are joined to each other at one of their ends (11) whilst the other ends are formed into hooks (15) which grip the wall of the blood vessel (16). The filter (10) is made from biologically decomposable material and is operational for only as long as is necessary to achieve its therapeutic purpose. In the implanted condition the part of the filter furthest from the wall of the blood vessel decomposes more quickly than the parts close to the blood vessel wall. USE - Blood vessel filter.

Control strategy for multi-module parallel converter system

Abstract: A systematic control-loop design procedure for a multimodule converter system for high-current, low-voltage applications is presented. A small-signal model of the system is derived using the PWM (pulse width modulation) switch model and the small-signal model of the current mode control. The small-signal model for the multimodule converter system is simplified to a equivalent single-module model. The control-loop design is implemented using the single-module model. A three-loop control strategy for the multimodule converter system with a secondary output filter is developed. Significant improvements of small-signal performance and module-failure response are achieved using additional feedback from the intermediate filter stage. The small-signal analysis of the three-loop controlled converter is performed, focusing on the effects of the local voltage feedback on the closed-loop performance of the system. It is shown that local voltage feedback minimizes any detrimental effect of the resonance between the power stage filter of each converter module and the common output filter. >

Thin film filter performance for extreme ultraviolet and x-ray applications

Abstract: Substantial work has been done to characterize filter materials for the vacuum ultraviolet and x-ray regions of the electromagnetic spectrum. This paper summarizes the theoretical basis for predicting performance and compiles the results of different measurement programs for comparison. Recent work that better quantifies transmission as a function of wavelength for various filter and window materials is reported. Other applications of thin films in which these optical properties are important include photocathodes and x-ray laser targets. Of particular interest are figures giving linear absorption coefficients as a function of wavelength for commonly used filter materials. Also included are recent data on the effect of aging on aluminum filters, plus test data and comments on the use of composite materials designed to adjust the bandpass of a filter to meet particular research requirements. The data are presented so that the reader may more easily design and predict the performance of filters and windows for specific applications.

Device manufacture involving lithographic processing

Abstract: Fabrication of devices of micron and submicron minimum feature size is accomplished by lithographic processing involving a back focal plane filter. A particularly important fabrication approach depends upon mask patterns which produce images based on discrimination as between scattered and unscattered radiation by accelerated electrons.

Method and apparatus for detecting blood vessels and displaying an enhanced video image from an ultrasound scan

Abstract: The system for detecting blood vessels and displaying an enhanced video image from video images obtained from an ultrasound scanner includes, in one embodiment, a target filter which limits the area in the video image to a predetermined size and an edge detector which senses gradients in pixel values in that target area. The edge detector marks transitional pixels at gradients exceeding a certain level. The system also includes a monitor for displaying the video image obtained from the ultrasound scanner. The marked transitional pixels are displayed in a contrasting color compared to the concurrently displayed input video image. In one embodiment, the target filter detects motion by comparing moving image block target areas separated in both time and space, counting moving image blocks and further limiting the target area to areas having the highest number of moving image blocks. Accordingly, smaller target areas are processed with the edge detector. In another embodiment, the target filter includes a gross edge detector, a transitional pixel counter and a further target filter which prioritizes the various the initial target areas such that the target area having the highest number of maaraked pixels is selected as the area to be further processed by the edge detector. In both embodiments, the electronic processing occurs in real time. A method is disclosed for detecting blood vessels and displaying an enhanced video image from a plurality of video images obtained from an ultrasound scanner.

A cheap quantum sensor using a gallium arsenide photodiode

Abstract: A new quantum sensor for measuring photosynthetically active radiation (PAR) was designed using a gallium arsenide photodiode. This sensor is cheap and effectively measures radiation between 400 and 700nm without any filter, which allows both high output level and easy manufacturing. A comparison with two other commercially available quantum sensors (Li-Cor and Macam sensors) was made. The sensor des- cribed here was less sensitive than the two others both in the blue and far-red parts of the spectrum. Its maximum sensitivity is near 600nm. However it was shown, under natural light and several artificial light sources, that the results given by the three sensors were very similar. Nevertheless some problems could arise with monochromatic light sources such as sodium lamps whose spectrum is mainly composed of radiation between 570 and 620nm. This study also shows that gallium arsenide sensors are suitable for PAR measurements under canopies.

Method for producing infusion coffee filter packs

Abstract: A method is disclosed for producing infusion coffee filter packs in which a first strip of filter paper is placed adjacent to a mold having a cylindrical mold pocket, and the strip of filter paper is caused, either mechanically or by a vacuum, to conform to the cylindrical mold packet. The conforming step causes the surface area of the first strip of filter paper to stretch and increase by at least three percent relative to its area prior to the conforming step. A measure quantity of ground coffee is then deposited into the mold packet over the filter paper conformed thereto. A second strip of filter paper is placed over the first strip of filter paper and the ground coffee in the mold packet. The first and second strips of filter paper are then sealed together around the coffee filled mold pocket, as by a heat sealing press pressing and sealing the strips together. The filter paper is then trimmed as by die cutting to product a half inch wide flange area extending around the mold pocket. The presence of the one half inch flange in combination with the increased surface area caused by stretching results in a brewed coffee having an increase in soluble solids extraction and a decrease in the standard deviation of soluble solids extraction.

Diesel engine exhaust filtration system and method

Abstract: A diesel engine exhaust filtration system and method which removes both diesel particulate matter (DPM) and unburned hydrocarbons (UHC) from the exhaust gases Two filters in parallel are used, each alternating operation as the other regenerates Each filter is preferred to be constructed in a conventional manner and operates at between 100 to 300 degrees Centigrade A microprocessor controlled valve system regulates which filter is active and which is regenerating and/or inactive DPM accumulates at the active filter, with UHC condensing on the DPM When the active filter becomes clogged, the microprocessor switches it to inactive status, and switches the other filter to active status Low temperature regeneration is initiated by the microprocessor in which DPM and UHC burn slowly across the entire filter A recirculation conduit provides for the gases produced by the regeneration to be directed to the air intake of the diesel engine Any remaining UHC or DPM will be subsequently burned in the combustion chambers of the diesel engine or taken out by the other active filter When regeneration has completed, the inactive filter will await being switched by the microprocessor to active status when the other filter has become sufficiently clogged that it is time for it to be regenerated

Downhole pump filter

Abstract: A downhole pump filter filters sand and other solid particles from well fluids prior to passage of the fluids through the intake nut of a well pump. A cylindrical coupling has an externally threaded upper end which coaxially screws into the pump intake nut. The coupling also has an externally threaded lower end. A tubular member coaxially secured within the lower end of the coupling has a plurality of perforations dispersed at least along its lower portion. A filter sock may encase the perforated portion of the tubular member to block smaller sand or other solid particles from entry into the tubular member perforations. A cylindrical casing with a closed lower end and an internally threaded upper end coaxially screws onto the exxternally threaded lower end of the coupling with the tubular member and the filter sock disposed within the casing. The casing has a plurality of perforations dispersed at least along its lower poriton. The casing perforations, the filter sock, if any, the tubular member perforations and the cylindrical coupling sequentially communicate to form a flow path for well fluid into the pump intake nut.

Second generation switched-current signal processing

Abstract: A switched-current integrator configuration with greatly improved sensitivity to transistor mismatch is described. Forward-Euler, backward-Euler, and bilinear-z mappings are described, as well as an integrator which responds to the derivative of the input current. An universal integrator configuration which performs an identical algorithm to a well-known switched-capacitor universal integrator is developed. It can be used to translate known switched-capacitor filter topologies into switched-current counterparts, as is demonstrated by the simulation of a sixth-order low-pass filter. >

Molten metal pump with filter

Abstract: A molten metal pump (10) includes a filter (30) that prevents ingestion of foreign material such as dross from molten metal within which the pump (10) is immersed. The filter (30) is a large structure that is secured to the base of the pump (10) surrounding the pump's inlet. The filter (30) forms a cavity (36) adjacent the pump's inlet. The ratio of the surface area of the filter (30) to the inlet area of the pump (10) is very large: the filter (30) has a low porosity while maintaining a high flow rate for the pump (10).

Solid-state color imaging device

Abstract: A solid-state color imaging device includes a plurality of elements aligned vertically and horizontally, each element sensitive to particular color. A white band filter is further provided that extends between rows of horizontally aligned elements.

CMOS digital clock and data recovery circuit

Abstract: An integrated circuit for recovering the clock and data information from phase-encoded serial data The circuit includes a synchronous delay line coupled to a waveform digitizer and a waveform synthesizer The waveform digitizer receives and converts the phase-encoded data into a string of bits whose value represent the logic levels of an encoded data at T p /N intervals where T p is the reference clock period and N is the resolution of the waveform digitizer The encoded data may be one of several phase-encoded serial data such as Manchester coding The digitized output from the waveform digitizer is input to a transition detector, where the locations of the transitions (bit-boundary transitions and bit-center transitions) of the digitized encoded data are extracted An AND stage comprising N AND gates is coupled to the waveform digitizer and the waveform synthesizer for masking out the bit-boundary transitions and passes the bit-center transitions The output from the AND stage (a binary word) is coupled to a pair of encoders The encoders are coupled to an adder and an L-type register which are used for compensating for missing bit-center transitions or for the presence of two bit-center transitions A digital filter coupled to the L-type register allows the present invention to achieve lockon immediately and to filter out phase jitter The digital filter is further coupled to a shifter in the waveform synthesizer for synthesizing the clock information of the encoded data on one hand, and for providing mask bits to the AND stage on the other hand The clock information of the encoded data is synthesized by the shifter in the waveform synthesizer over a digital-to-time domain converter in the waveform synthesizer Finally, the data information of the phase-encoded serial data is regenerated by a D-type flip flop which receives encoded data over a delayed stage from its D input and also receives the clock information over its clock input

Bandwidth management: A congestion control strategy for broadband packet networks — characterizing the throughput-burstiness filter

Abstract: A congestion/flow/error control architecture for broadband packet networks, based on a “core” network congestion control strategy called Bandwidth Management (BWM), is described. Associated with this control architecture is a set of traffic/performance analysis modules for quantitatively assessing the overall control performance. A particular module, that quantitatively characterizes a “throughput-burstiness filter” associated with BWM, is studied through an analytically tractable traffic model, and results of analysis of this model are used to illustrate the operation of the BWM controls.

Air intake filter for internal combustion engines

Abstract: An air intake filter for internal combustion engines has a flat, replaceable filter insert 20, through which the air flows transversely in operation, and which has a gasket 22 disposed on the periphery for sealing at the face side against a ledge 15 of the filter housing 11. The insert can be inserted into the filter housing through a narrow side, the sealing pressure being produced by a cover 50 which has two sliding wedges 51 and 53. To bring it about that, when the sealing pressure is applied, the gasket 22 will not be shifted laterally with respect to the ledge 15 of the filter housing 11, the cover, which is in the form of a substantially open frame, replaceably accommodates the filter insert. The cover is provided with cams 40 and 41 which serve to fix the frame 30 in an extended position during the replacement of the filter insert. Also the lateral walls 25 and 26 of the filter housing and the lateral walls 45 and 46 of the frame 30 are inclined wedgewise to avoid large frictional forces between the adjacent surfaces when the filter is installed and removed.

Efficient reconstruction of band-limited sequences from nonuniformly decimated versions by use of polyphase filter banks

Abstract: An efficient polyphase structure for the reconstruction of a band-limited sequence from a nonuniformly decimated version is developed. Theoretically, the reconstruction involves the implementation of a bank of multilevel filters, and it is shown that how all these reconstruction filters can be obtained at the cost of one Mth band low-pass filter and a constant matrix multiplier. The resulting structure is therefore more general than previous schemes. In addition, the method offers a direct means of controlling the overall reconstruction distortion T(z) by appropriate design of a low-pass prototype filter P(z). Extension of these results to multiband band-limited signals and to the case of nonconsecutive nonuniform subsampling are also summarized, along with generalizations to the multidimensional case. Design examples are included to demonstrate the theory, and the complexity of the new method is seen to be much lower than earlier ones. >

Simulated annealing algorithm for binary phase only filters in pattern classification

Abstract: A binary phase only filter is encoded with a simulated annealing algorithm to classify two similar characters in a variety of fonts. Characters that cannot be distinguished with conventional filter encoding methods are clearly distinguished with the optimized binary phase only filter using a simulated annealing algorithm. This method gives zero error classification rate for tested characters. Correlation performance of the optimized binary phase only filter is compared with the binary phase only filters encoded with conventional methods. The computational requirements for optimizing the filter are not excessive.

Format conversion preprocessing method and circuit

Abstract: A preprocessing method and circuit is utilized to convert a video sequence between a high resolution interlaced format used when the video sequence is read out of a storage medium and a low resolution progressive format suitable for compression encoding at a low bit rate. In accordance with the inventive format conversion preprocessing algorithm, the video sequence in the high resolution interlaced format is first processed by a linear filter with a diamond-shaped passband in y-t space. The output of the linear filter is processed by a non-linear filter and the resulting signal is then decimated to produce the video signal in the low resolution progressive format. The inventive preprocessing algorithm serves to eliminate aliasing, noise, and jerkiness of motion from the sequence in the low resolution progressive format.