Showing papers on "Filter (video) published in 1973"

Practical design rules for optimum finite impulse response low-pass digital filters

Abstract: Although a great deal is known about design techniques for optimum (in a minimax error sense) finite impulse response (FIR) low-pass digital filters, there have not been established any practical design rules for such filters. Thus, a user is unable to easily decide on the (approximate or exact) filter order required to meet his design specifications and must resort to tables or trial and error procedures. In this paper, such a set of design rules is given. In the case of very narrow bandwidth or very wide bandwidth filters, analytic relations between the filter parameters can be readily obtained. In all other cases, exceedingly good linear and nonlinear fits to the data can be obtained over somewhat restricted ranges of the parameters. These fitting procedures lead to a practical set of simple design rules for estimating filter order from the desired specifications.

Identification of optimum filter steady-state gain for systems with unknown noise covariances

Abstract: A discrete linear stationary system is considered for which the input noise covariance Q and the output noise covariance R are unknown. A stable filter with a suboptimal gain is assumed. An identification scheme is presented which uses the autocorrelation functions of the innovations sequence of the suboptimal filter to determine the optimum filter steady state gain \Gamma directly without the intermediate determination of the unknown covariances Q and R . The approach used is to identify an output equivalent representation of the original system which does not involve the unknown covariances directly.

A Decision - Directed Adaptive Tracker

Abstract: In the design of a tracking filter for air traffic control (ATC) applications, a maneuvering aircraft can be modelled by a linear system with random noise accelerations. A Kalman filter tracker, designed on the basis of a variance chosen according to the distribution of the potential maneuver accelerations, will maintain track during maneuvers and provide some improvement in position accuracy. However, during those portions of the flight path where the aircraft is not maneuvering, the tracking accuracy will not be as good as if no acceleration noise had been allowed in the tracking filter. In this paper, statistical decision theory is used to derive an optimal test for detecting the aircraft maneuver; a more practical suboptimal test is then deduced from the optimal test. As long as no maneuver is declared, a simpler filter, based on a constant-velocity model, is used to track the aircraft. When a maneuver is detected, the tracker is reinitialized using stored data, up-dated to the present time, and then normal tracking is resumed as new data arrives. In essence, the tracker performs on the basis of a piecewise linear model in which the breakpoints are defined on-line using the maneuver detector. Simulation results show that there is a significant improvement in tracking capability using the decision-directed adaptive tracker.

Optical interference authenticating means

Abstract: An optical interference, authenticating means, comprising a substrate, and a filter composed of at least one optical interference layer having a known characteristic of spectral reflectance and a different, known characteristic of spectral transmittance, both of which vary with the angle of incidence of light on the filter. The substrate, which may be a portion of a valuable document such as a bank note, has a portion of the surface adjacent to the filter coloured to absorb some of the light transmitted by the filter.

New results in optimizing surveillance system tracking and data correlation performance in dense multitarget environments

Abstract: Tracking performance in surveillance systems depends on two interrelated functions: track updating, the process of incorporating a new measurement into the track to update the system state estimate, and return-to-track correlation, the process of selecting which sensor return, if any, to use for track updating. Because of the presence of a number of targets in the same vicinity and the existence of clutter and false alarms, the correlation function is generally performed imperfectly. Since typical tracking filters such as the Kalman filter do not account for such correlation errors, degraded performance often results as well as unreliable and optimistic estimates of tracking accuracies. This paper examines and provides for optimizing the overall tracking process considering both the correlation and track update functions and their interaction. General equations for tracking performance of any arbitrary tracking filter used with a broad class of correlation algorithms in dense multitarget environments are developed. A new reoptimized tracking filter is derived which provides, from among a general class of tracking filters using a priori information on sensor return statistics, optimal performance in such environments and which reduces to the Kalman filter when environmental effects are eliminated. The new filter is compared parametrically to both the standard Kalman filter and a computationally simpler version of the optimal filter in terms of tracking accuracy and reliability of the calculated covariance matrix, over a spectrum of environmental conditions. At high densities of sensor returns, the new filter provides considerably improved tracking performance as well as uniquely reliable estimates of this performance.

Approximate design relationships for low-pass FIR digital filters

Abstract: In this paper, a set of simple, approximate relationships between FIR, linear phase, low-pass filter parameters is presented. Based on these relationships, it is shown how an existing, readily available, filter design program can be used to efficiently design low-pass filters that meet or exceed arbitrary input specifications.

Study of Vortex Rings Using a Laser Doppler Velocimeter

Abstract: filter resulting when the gyro drifts, accelerometer errors, and DME biases are neglected performs nearly optimally. Hence, alignment can be accomplished by using an eighth-order filter when using one VOR/DME, or a seventh-order filter when using two DME's. The quantitative results presented here are, of course, dependent upon the validity of the error models assumed. In particular, the VOR/DME error model proposed here has not been as thoroughly checked experimentally as the inertial navigation system model.

Cylindrical filter elements with improved side seam seal

Abstract: Cylindrical filter elements are provided having an improved side seam seal, which can be bonded to end caps in a leak-tight manner.

Multi-component infrared analyzer

Abstract: A multi-component nondispersive infrared correlation spectrometer for selectively analyzing for a plurality of gases of interest in a gaseous mixture utilizes a rotating filter wheel containing filter systems corresponding to each gas of interest sought. Each filter system contains an ordered pair of filters to sequentially create filtered reference and analysis paths for each gas of interest between a source of infrared radiation and a detector. Special synchronization and signal analysis systems are provided to produce an output signal for each gas of interest. These systems are coordinated with the rotation of the filter wheel in a manner which allows a plurality of gases of interest to be analyzed with simultaneous output.

Tracking system utilizing Kalman filter concepts

Abstract: A monopulse radar tracking system is disclosed employing four tracking channels, one for each of range, velocity, azimuth and elevation. The two angle channels are referenced directly to antenna coordinates. Each channel is mechanized by a stored program in a digital computer, and the mechanization employs Kalman filtering with gain factors continually optimized for measured signal-to-noise ratios. Angular rate commands for the antennas are obtained by passing pointing error estimates from the angle channels through a compensator for antenna motion and adding line-of-sight rate estimates from the angle filter channels. Cross-coupling between channels is provided, and each channel is aided by outputs from an inertial navigation platform. Preaveraging of discriminants received between computational cycles is provided.

Electrostatic dust filter

Abstract: An electrostatic dust filter is provided for collecting electrically-charged dust particles which are deposited on fabric filter elements in an electric field so that the particles deposit in porous layers. The dust particles are charged in a manner to provide a mixture of particles charged with opposite polarities, and adjacent filter members are maintained at opposite polarities. Unidirectional electric fields thus exist between adjacent filter elements and the dust particles deposit on one or the other filter element according to their polarity. A relatively simple structure is provided which requires no separate electrodes to maintain the electric field.

Methods and apparatus for testing earth formations composed of particles of various sizes

Abstract: In the representative embodiments of the new and improved methods and apparatus disclosed herein for testing earth formations of differing compositions, fluid-admitting means carrying a selectively-sized filter of a unique design are selectively extended into sealing engagement with a potentiallyproducible earth formation and operated so as to establish communication with the isolated formation without the fluidadmitting means being plugged with mudcake from the formation wall. Should, however, loose formation materials enter the fluidadmitting means as the testing is conducted, the filter is uniquely arranged to collect these loose materials and halt the further erosion of such materials from the formation wall so as to assure continued communication with the isolated formation.

Bag type filter device

Abstract: A filter device formed of filter tubes each of which is composed of a filter bag disposed between inner and outer wire cages with the longitudinally extending wires of the inner cage extending beyond some of the longitudinal wires of the outer cage to engage the filter bag therebetween in a configured relation.

Aided Tracking as Applied to High Accuracy Pointing Systems

Abstract: Two basic concepts of rate aided tracking and position aided tracking are applied to a conventional pointing system in order to improve performance. The aided track signals are derived in an inertial space format and are generated from a Kalman filter algorithm. Computational results are included to show the interplay between the conventional pointing system and the aided track filter.

Device for detecting carbon on cigarette filter tips

Abstract: Device for detecting faults, such as carbon granules, smudges, and/or other dark areas on the end of cigarette filters, including sources of light energy for casting light on a cigarette filter being inspected, photocells positioned for individually scanning the filter tips as the cigarettes travel on a conveyor through an inspection zone, and a detection circuit for producing a floating reference signal which is derived from the highest repeating signal levels from normal filter tips previously inspected. The detection circuit compares the instantaneous signals produced from the photocells with the floating reference signal in a manner whereby the dark area, resulting from a fault such as a carbon particle, when scanned by the photocells will produce an instantaneous sensing signal differing from the floating reference signal so as to indicate the presence of a fault. The detection circuit automatically compensates for variations in color and texture of the filter tip material that could otherwise cause detection failure when utilizing a fixed type of reference. According to a further embodiment, the detection circuit includes an amplifier-filter section having a frequency response characteristic which enables the device to detect the smaller size faults with substantially the same ease as the relatively larger size faults.

A selective de-heparinizer filter made of new cross-linked polymers of a poly-amido-amine structure.

Abstract: Dae polimeri reticolati di nuova sintesi, contenenti gruppi amminici terziari, sono in grado di assorbire selettivamente eparina dal sangue. Essi non sono emolitici e non interferiscono con i fattori della coagulazione.

The Design and Applications of Highly Dispersive Acoustic Surface-Wave Filters

Abstract: The development of a low-loss broad-band linear FM dispersive filter having a time-bandwidth (TB) product of 1000 is discussed. Two systems applications for highly dispersive linear FM filters--pulse compression RADAR and a microscan receiver--are discussed with emphasis on filter performance requirements. The principal factors which influence the design of surface-wave filters are reviewed and theoretical design procedures are outlined. The 1000:1 filters, which are implemented on strong-coupling YZ lithium niobate, typically meet the design goal of a 100-MHZ rectangular passband and have a CW insertion loss of less than 35 dB. Measured data are presented for the filter performance in a pulse-compression loop and in a prototype broad-band microscan (compressive) receiver.

Simultaneous Two-Way Data Transmission Over a Two-Wire Circuit

Abstract: Simultaneous two-way (full-duplex) data transmission in the same bandwidth normally requires separate channels, and in the telephone network is realized by using a four-wire circuit. This paper reports on investigations directed toward full-duplex operation on a two-wire circuit using a hybrid coupler and a passband automatic transversal filter at each end of the circuit to separate the two signals. Full-duplex binary transmission at a rate of 2000 Bd in each direction has been experimentally demonstrated on a limited number of twowire circuits. Photographs of eye patterns are provided to illustrate the substantial improvement over operation with hybrids alone. Limitations on performance due to unstable distant echoes are described.

Fully tunable Lyot-Öhmann filter.

Abstract: The design and performance of an Aerobee 150 rocket-borne solar spectrograph covering a wavelength range of 10-385 A are discussed. The spectrograph uses a gold-coated replica concave grating of 3-m radius with 1200 grooves/mm at an angle of incidence of 88 degrees . The spectra are recorded on glass photographic plates making possible wavelength determination to 0.003 A if known standard wavelengths occur frequently enough. Special attention to scattered light made possible the photographing of the solar spectrum from 60 A to 385 A without using filters to absorb the strong visible and uv sunlight, although the solar spectrum was also recorded through metal foil filters. In the laboratory the spectrograph has been used to record spectra of highly ionized metals with a resolution of 0.03 A or better.

Dust filter apparatus

Abstract: Dust filter apparatus comprises a first, coarse dust removal stage constituted by a plurality of swirl chamber devices into which a liquid is sprayed and a second, fine dust removal stage constituted by a wetted filter panel.

Vehicle washing plant

Abstract: A vehicle washing plant fitted with a water recycling circuit providing water for a washing cycle and a rinsing cycle and including a main filter containing a granulated filter medium, preferably activated carbon, and a back-wash filter, the circuit being connected to supply water for the rinsing cycle firstly through the back-wash filter and subsequently through the main filter with preferably water for the washing cycle passing through the back-wash filter only; two preferred types of main filter are described which comprise a plurality of filter receptacles connected in series within a common casing at least one of the receptacles being easily replaceable.

Color television camera optical system

Abstract: An optical system in a single or double tube color television camera for minimizing color shading, moire patterns and color beats includes along the image optical axis a phase grating low pass filter, a color encoding filter and a lenticular lens member oriented relative to each other and the image scanning to minimize interference between the color encoding filter and striped patterns in the viewed object. The color encoding filter is striped, the low pass filter is either striped or has regularly longitudinally and transversely spaced phase retarding projections and the lenticular lens member includes transversely spaced longitudinal cylindrical lenses or regularly transversely and longitudinally spaced convex projections.

High performance filter assembly

Abstract: A high performance filter assembly includes an outer casing adapted for insertion in the ductwork or plenum of an air treating system. A drawer is removably secured within the casing and contains an improved pleated filter media of the high efficiency type. The upstream portion of the drawer is sealed to the casing by a cam arrangement, and double blankets are disposed at the drawer ends and casing ends to further prevent air leakage. The pleated filter itself is collapsible for easy storage, and expands to a fixed position when installed. Reinforcements on the outermost walls of the pleated filter prevent possible tearing of the filter during its installation and also support said walls during filter expansion. The elongated filter edges are sealed to the drawer by a member which also functions to secure a plurality of filter-supporting fingers.

Television signal distribution system

Abstract: A television signal distribution system for special programs in an establishment, as a motel, with plural receivers. A master antenna is connected through a cable distribution system with each of the receivers. Special program signals, as of a movie, are distributed through the cable on an unused channel. A filter at each receiver blocks the special signal from the receiver. A circuit actuated from a central control station is directed to the room over the telephone system and disables the filter enabling the occupant of the room to watch the special program.

Second-order digital filter with only one magnitude-truncation quantiser and having practically no limit cycles

Abstract: A 2nd-order digital filter with only one magnitude-truncation quantiser is discussed, and results are given that indicate that limit cycles are almost absent in this filter.

Wide-band multilayer interference filter

Abstract: A wide-band multilayer interference filter comprises a filter having a periodic arrangement of layers of the structure ABCDDCBA, where A,B,C,D indicate individual layers having each an optical thickness of one-fourth of the predetermined constructional wavelength and the mutually different refraction indices of said layers fulfill the following conditions:

Quick-clean vent filter

Abstract: A filter unit including a circular housing containing replaceable filter pads, and further having permanent magnets attached to the housing for attaching the filter unit over a fan grill opening.

Adjustable electronic tunable filter with simulated inductor

Abstract: A stable tunable Q bandpass filter adapted to have its parameters dynamically varied over a wide range of bandwidths and center frequencies. The filter includes a capacitor and a network coupled in parallel across the capacitor. The network includes a plurality of operational amplifiers coupled to simulate an inductor without utilizing coils. A feature of the filter is that it can be readily made adaptive to track an input signal which may randomly vary in frequency. A further feature of the invention is to have one input of each operational amplifier coupled directly to ground to minimize stray capacitance. The performance characteristics of this filter are in part attained by the method of component layout and shielding techniques used, in addition to the method of circuit excitation.