Showing papers on "Filter (video) published in 1987"

A 4-MHz CMOS Continuous-Time Filter with On-Chip Automatic Tuning

Abstract: This paper presents a 3rd order low-pass continuous-time filter with 4 MHz cut-off frequency, integrated in a 3 ?m CMOS process. The design approach is based on the direct simulation of a doubly-terminated LC ladder using capacitors and fully-balanced, current-controlled transconductance amplifiers with extended linear range. PLL techniques, involving a 8.5 MHz controlled oscillator that matches a specific part of the filter, are used to realize on-chip automatic tuning. The complete circuit features 71 dB dynamic range and consumes only 16 mW from a single 5 V supply.

Dispersion cancellation using linearly chirped Bragg grating filters in optical waveguides.

Abstract: The use of a linearly chirped Bragg grating filter for dispersion cancellation in an optical-fiber link is discussed. Numerical and theoretical calculations are made, which show that, with the proper taper function, the filter can have a high reflectivity and a quasi-constant nonzero dispersion, proportional to the inverse of the chirp. The filter can compress dispersion-broadened pulses by factors of 2-5 or more, if many filters are cascaded. Its compactness and efficiency would make it suitable for on-line implementation.

Detection filter design: Spectral theory and algorithms

Abstract: A new formulation of the detection filter problem is generated by assignment of the closed-loop eigenstructure under certain constraints. Detection filters, which are actually a specific class of observers, fix the output error direction of the system so that it can be associated with a particular failure mode and its known design failure direction. The derivation of detection filters from an eigensystem assignment approach permits a very transparent theory. The detection filter gains and closed-loop eigenvectors are obtained from a set of simultaneous equations. Necessary and sufficient conditions for the solution of these algebraic equations are determined which produce a complete theory for detection filters.

The packer filter: an efficient mechanism for user-level network code

Abstract: Code to implement network protocols can be either inside the kernel of an operating system or in user-level processes. Kernel-resident code is hard to develop, debug, and maintain, but user-level implementations typically incur significant overhead and perform poorly.The performance of user-level network code depends on the mechanism used to demultiplex received packets. Demultiplexing in a user-level process increases the rate of context switches and system calls, resulting in poor performance. Demultiplexing in the kernel eliminates unnecessary overhead.This paper describes the packet filter, a kernel-resident, protocol-independent packet demultiplexer. Individual user processes have great flexibility in selecting which packets they will receive. Protocol implementations using the packet filter perform quite well, and have been in production use for several years.

Tracking a Maneuvering Target Using Input Estimation

Abstract: The conventional Kalman tracking filter incurs mean tracking errors in the presence of a pilot-induced target maneuver. Chan,Hu, and Plant proposed a solution to this problem which used themean deviations of the residual innovation sequence to make corrections to the Kalman filter. This algorithm is further developedhere for the case of a one-dimensional Kalman filter, for which an Implementable closed-form recursive relation exists. Simulation results show that the Chan, Hu, and Plant method can accurately detect and correct an acceleration discontinuity under a variety of maneuver models and radar parameters. Also, the inclusion of thislogic into a multiple hypothesis tracking system is briefly outlined.

Quadruple mode filter

Abstract: A quadruple mode bandpass filter has at least one cavity resonating in four independent orthogonal modes simultaneously. Preferably, the filter has two cavities, one cavity being a quadruple mode cavity and the remaining cavity being either a single mode, dual mode, triple mode or quadruple mode cavity. By introducing a resonant feedback coupling into filters of the present invention, the number of transmission zeros produced by the filter is equal to the order of the filter. Previous filters have cavities resonating in either a single, dual or triple mode and the maximum number of transmission zeros is equal to the order of the filter minus two.

High-frequency generator with automatic power-control for high-frequency surgery

Abstract: A high-frequency generator having automatic power-control for use in high-frequency surgery. The frequency of a high-frequency generator is adjustable by electronic circuit brought by a control circuit to a value such that at the output of the power amplifier there is an optimal phase relation between output voltage and output current, i.e., generally a phase shift of zero. The signal necessary for the control of the output power is obtained from harmonic oscillations generated by the arc at the surgical probe. A harmonic-measuring device to obtain the harmonic oscillations generated by the arc at the surgical probe has a phase-controlled rectifier which is controlled by the oscillator of the high-frequency generator. A simple filter is used at the output of the power amplifier, and the measurement filter used before the harmonic-measuring device can either be completely eliminated or need only be very simple in construction. No complicated filter adjustment is necessary and the power generator operates under optimal conditions and exhibits enhanced operating reliability.

Coalescing filter for removal of liquid aerosols from gaseous streams

Abstract: A coalescing filter capable of removing liquid aerosols (such as water and oil) from gaseous streams with high efficiency. The filter comprises three layers, (a) an intermediate fibrous layer having a pore size of from about 1.25(t) to about 2(t), where t is the dynamic film thickness of the aerosol in the gaseous stream, the fibers of the intermediate fibrous layer having diameters ranging from about 0.1 to about 20 micrometers, (b) a fibrous layer upstream of the intermediate layer having a pore size greater than the intermediate layer, and (c) a downstream fibrous layer having a pore size greater than the intermediate layer and wherein the critical surface energy of each layer of the filter is less than the surface tension of the liquid making up the aerosol.

Filter for making portions of coffee or tea

Abstract: The invention relates to A filter for making portions of coffee or tea, comprising a substantially cup-shaped supporting vessel having a pouring-in opening at the top, a chamber for filling with liquid and having an outlet opening at the bottom, and a filter insert disposed in the supporting vessel above the outlet opening, wherein the filter insert (5) comprises a filter mat and extends approximately parallel to the inner wall of the supporting vessel and its periphery is connected to the supporting vessel (1) in the edge region of the pouring-in opening (2).

Method for determining the bubble point or the largest pore of membranes or filter materials

Abstract: In determining the bubble point or the largest pore of a membrane or a filter material, the membrane or the filter material is placed in a container, wherein the membrane or the filter material divides said container into two spaces. Thereafter, the first chamber with gas, and the second space and the pores of the membrane (of the filter material) is filled with a wetting liquid. Now the pressure in the gas chamber is increased at least until the gas displaces the liquid from the largest pore. By this ruling headspace pressure of the bubble point is set, or the cross-sectional dimension of the largest pore can be calculated. According to the invention it is proposed that the bubble point corresponding to the gas chamber pressure is then determined by measurement of the sound intensity in the liquid chamber when an abrupt increase in the sound intensity occurs. The measurement of the sound intensity is carried out preferably in the ultrasonic range.

Truncated subband coding of images

Abstract: Image data is analyzed in a number of iterated analysis procedures, using two-dimensional quadrature mirror filters to separate low-pass spatial filter response component and three differently oriented high-pass spatial filter response components, which filter response components are decimated in both dimensions. The high-pass filter response components are coded as is. The low-pass filter response component is coded as is only in the last iteration; in the earlier analysis procedures the low-pass filter response component provides the input data for the secceeding analysis procedure.

Dual channel P-wave detection in surface electrocardiographs

Abstract: A method and apparatus for reliably detecting the P-wave component in a surface electrocardiograph. An adaptive Least Means Square filter is implemented in a programmed computer and the computer receives as its inputs a digitized version of the ECG waves picked up from two discrete locations on a subject's chest wall. The LMS adaptive filter functions to accommodate the energy component of the QRS complex thereby leaving the P-wave as the paramount signal component in the filter's "error" output.

Flavored cigarette filters, and methods and apparatus for making same

Abstract: A cigarette filter has a substantially cylindrical inner member of filter material surrounded by an outer member of filter material and a plugwrap. The density of the inner and outer members are typically different, and a flavorant is added to at least one of the members. Methods and apparatus for making the filter are also disclosed.

Capacitive separating circuit

Abstract: In the capacitive isolating section for DC isolation of a coaxial cable, a radio-frequency filter, preferably a low-pass filter, is provided in addition to an isolating capacitor in the outer conductor, by means of which the shielding characteristics of the isolating section are considerably improved. The isolating capacitor in the outer conductor can be a part of the radio-frequency filter. The attenuation characteristics of the isolating section can be improved even further by means of several radio-frequency filters connected in the manner of a cascade.

Resonator Memories And Optical Novelty Filters

Abstract: Optical resonators having holographic elements are potential candidates for storing information that can be accessed through content-addressable or associative recall. Closely related to the resonator memory is the optical novelty filter, which can detect the differences between a test object and a set of reference objects. We discuss implementations of these devices using continuous optical media such as photorefractive ma-terials. The discussion is framed in the context of neural network models. There are both formal and qualitative similarities between the resonator memory and optical novelty filter and network models. Mode competition arises in the theory of the resonator memory, much as it does in some network models. We show that the role of the phenomena of "daydream-ing" in the real-time programmable optical resonator is very much akin to the role of "unlearning" in neural network memories. The theory of programming the real-time memory for a single mode is given in detail. This leads to a discussion of the optical novelty filter. Experimental results for the resonator memory, the real-time programmable memory, and the optical tracking novelty filter are reviewed. We also point to several issues that need to be addressed in order to implement more formal models of neural networks.

Two‐dimensional top hat filter for extracting spots and spheres from digital images

Abstract: SUMMARY The top hat filter is a computer algorithm that extracts small, compact or rounded objects from digital images. Examples show application of the filter to micrographs and electron diffraction patterns.

Architectures and design techniques for real-time image-processing IC's

Abstract: A set of eight chips that perform real-time image-processing tasks was designed and fabricated with a 4-/spl mu/m NMOS technology. The chips include a 3/spl times/3 linear convolver, a 3/spl times/3 sorting filter, a 7/spl times/7 logical convolver, a contour tracer, a feature extractor, a lookup-table ROM, and two postprocessors for the linear convolver. All chips were designed with architectures that are dedicated to the particular image-processing task to be performed. The image-processing circuits operate on 10-MHz video data (512/spl times/512-pixel images). The design time for the chips was kept to 1.5 man-years by reusing hardware and using (and developing) appropriate CAD tools, ROM generators and a data-path generator were developed to reduce the circuit design time. An image recognition system was built with these custom chips that can recognize two-dimensional objects that are characterized by their closed outer contours. The complete system is controlled by a Sun workstation and operates at rates up to 15 frames/s. The recognition system achieved a 98% recognition rate for eight objects over a wide range of orientation and size variations and a 100% recognition rate without size variations.

Method of and apparatus for making streams containing fibrous materials of the tobacco processing industry

Abstract: A stream of filter tow which has been sprayed with atomized plasticizer is advanced past two detectors each of which monitors the density of the stream in a different way and generates corresponding signals which are processed by an evaluating circuit to generate modified signals which are indicative of the percentage of plasticizer. The modified signals are used to regulate the operation of a pump which controls the rate of admission of plasticizer to successive increments of the tow.

Integrated switched-capacitor filter with improved frequency characteristics

Abstract: A switched-capacitor filter constituted in the form of a semiconductor integrated circuit has an input circuit which consists of at least one noninversion-type switched-capacitor and at least two inversion-type switched-capacitors that are connected in parallel with each other. The two inversion-type switched-capacitors have different writing timings and reading timings relative to each other. With this setup, capacitances of the switched-capacitors need not be extremely increased even when it is desired to maintain a zero-point frequency of the filter at a very low value. Further, there is no need of providing a circuit such as sample holding circuit which requires extra area and consumes additional electric power.

Molten metal filter medium and method for making same

Abstract: A porous ceramic body of high structural strength and integrity is disclosed, along with the method of fabricating such, whereby a curable resin and a sinterable ceramic are mixed and then admixed to removable pore formers, then consolidated into a green body, the pore formers removed, and sintered into the porous ceramic body.

Convergence of the RLS and LMS adaptive filters

Abstract: The paper presents new convergence results for two adaptive filters: the RLS and LMS algorithms. Convergence of the exact RLS algorithm is studied when the forgetting factor \lambda is constant, which enables the adaptive filter to track time variations of the optimal filter. It is shown that, in the steady state, the squared deviation of the adaptive filter from the optimal one admits, with probability 1- \epsilon ( \epsilon arbitrarily small), an upper bound that is proportional to the (infinitesimal) quantity \mu = 1 - {\lambda} . This result agrees with the algorithm's practical behavior. The bound increases with the correlation degree of the filter inputs. This paper also provides an almost sure convergence result concerned with the LMS algorithm with decreasing step-size (infinite memory), used only when the optimal filter is asymptotically time-invariant, although the input statistics may be time-varying.

GaAs switched-capacitor circuits for high-speed signal processing

Abstract: Switched-capacitor building blocks are presented which are suitable for implementation in GaAs MESFET technology. They include gain stages, operational amplifiers, and transmission gates. Switched-capacitor design techniques are discussed that minimize filter sensitivity to GaAs op-amp limitations. Experimental results are presented on a variety of GaAs switched-capacitor circuits, including a gain stage, a second-order bandpass filter, and a third-order low-pass filter. The circuits demonstrate sampling rates exceeding 100 MHz without significant loss of accuracy.

Automatic device for the detection and shutoff of unwanted liquid flow in pipes

Abstract: A pipe flow detector for activating a solenoid to automatically close a pipe shutoff valve in the event of a leak. The detector comprises a piezoelectric film transducer attached to the pipe, the transducer producing a fluctuating electrical signal in response to pipe vibration. An amplifier amplifies the signal, which is then passed to a tunable low-pass filter. The output from the filter is passed to an averaging circuit to produce an electrical signal representative of the total voltage changes of the fluctuating electrical signals. An LED is connected to the output of the averaging circuit to provide a means to tune the filter. The filter may be tuned by: (a) providing a pipe flow substantially equal to the pipe flow that would occur in the presence of a leak and tuning the filter to provide the brightest output of the LED; (b) starting and stopping pipe flow and tuning the filter to a point where an output of the LED is generally present only in the presence of a flow; or, (c) externally causing a starting and stopping pipe vibration and tuning the filter to a point where the LED generally does not become brighter in response to the externally caused pipe vibration. During unattended operation, the averaging circuit output is passed through an RC timing circuit that passes the averaging circuit output after a preselected period of time. A latchable level detector receives the timing means output and, when a high enough signal level is received, sends a signal to a solenoid driver which drives the solenoid.

A 0.5-4.0-GHz Tunable Bandpass Filter Using YIG Film Grown by LPE

Abstract: A tunable bandpass filter using YIG film grown by liquid phase epitaxy (LPE) has been developed. Taking advantage of the very low resonance frequency in the perpendicular resonance of YIG film, an operation frequency of 0.5 GHz has been achieved. In order to make this filter operate up to 4.0 GHz, a new technique for multioctave tuning has been developed and applied to the filter. Over the wide tuning range from 0.5 GHz to 4.0 GHz, low insertion loss and high spurious suppression have been achieved. The performance of this filter satisfies the requirements for use as a tracking preselector in a microwave spectrum analyzer.

Multiple resonator component-mountable filter

Abstract: A dielectric block filter (501) which may be mounted on a printed circuit board or other substrate as a single component. The dielectric filter utilizes metallized hole foreshortened resonators (529-535) in the dielectric block (501), which employs capacitive coupling between resonators controlled in part by an electrode strip (553-558) coupled to the conductive material covering the majority of the dielectric block (501) surface. Input and output coupling is accomplished via terminals (505-507) asymmetrically arranged in a mounting bracket (503). Mounting tabs (515-523) on the bracket (503) opposite a recessed area holding the dielectric block secure the filter (501) to the circuit board and provide ground connection for the filter. Two or more filters (501) may be arranged on the circuit board to form a duplexer.

Efficient IIR and FIR fan filters

Abstract: A procedure for designing computationally efficient FIR and IIR fan filters is developed. The fan filters are derived from one-dimensional prototypes which are used in changing sampling rates by a factor of two. The transfer function B(z) of the prototype is expressed as B(z) = T_1(z^2)+zT_2(z^2) , which leads to a simple expression for the fan filter transfer function. The relation between the passband and stopband deviation requirements of the prototype and the fan filter is derived and employed in the design for meeting two commonly given sets of specifications. A special class of elliptic filters with zeros on the imaginary axis in the z plane is shown to yield computationally efficient IIR fan filters. FIR half-band filters are shown to be suitable one-dimensional prototypes for FIR fan filter design. In this case, symmetry constraints on FIR fan filter impulse response are automatically satisfied.