Showing papers on "Filter (video) published in 1989"

Perfect reconstruction FIR filter banks: some properties and factorizations

Abstract: Perfect reconstruction finite impulse-response (FIR) filter banks are analyzed both in the z-transform and time domains, showing the alternatives between designs in the two domains. Various classes of perfect reconstruction schemes are indicated, and relations between previously known systems are given. Windowed modulated filter banks with low computational complexity and perfect reconstruction are shown. New factorizations of polyphase filter matrices leading in particular to linear-phase filters, are given. The computational complexity and the architecture of the new structures are indicated. >

Simple coherent receivers for partial response continuous phase modulation

Abstract: By using a pulse-amplitude-modulation representation of binary continuous-phase-modulation signals, the authors develops a novel optimum Viterbi sequence detector and a near-optimum Viterbi receiver with low complexity. For modulation index 0.5, where a linear receiver can be used, a minimum-mean-squared-error linear receiver filter is derived. The performance of all of these is analyzed, using the Gaussian minimum-shift-keying signal (GMSK) for illustration. It is shown that a GMSK receiver consisting of two matched filters and a four-state Viterbi algorithm performs with less than 0.24-dB degradation compared with the optimal receiver. The linear receiver is optimum for all values of E/sub b//N/sub 0/ (bit-energy-to-noise one-sided spectral density ratio). A design method for its filter is given. The filter is equivalent to a cascade of a matched filter and a Wiener filter estimator. Both upper and lower bounds for the bit-error probability are calculated. Simulation results which confirm the analysis are given. >

Simple coherent receivers for partial response continuous phase modulation

Abstract: By using a pulse-amplitude-modulation representation of binary continuous-phase-modulation signals, the authors develops a novel optimum Viterbi sequence detector and a near-optimum Viterbi receiver with low complexity. For modulation index 0.5, where a linear receiver can be used, a minimum-mean-squared-error linear receiver filter is derived. The performance of all of these is analyzed, using the Gaussian minimum-shift-keying signal (GMSK) for illustration. It is shown that a GMSK receiver consisting of two matched filters and a four-state Viterbi algorithm performs with less than 0.24-dB degradation compared with the optimal receiver. The linear receiver is optimum for all values of E/sub b//N/sub 0/ (bit-energy-to-noise one-sided spectral density ratio). A design method for its filter is given. The filter is equivalent to a cascade of a matched filter and a Wiener filter estimator. Both upper and lower bounds for the bit-error probability are calculated. Simulation results which confirm the analysis are given. >

Holographic credit card with automatical authentication and verification

Abstract: A holographic credit card that uses a matched optical filter to store in form of a hologram a unique identification such as a fingerprint of the authorized user, a source of coherent light that provides the illumination, and the input element in the approval device for providing the angle-invariance, possessing the form of the transparent window, against which the user places and rotates the same fingerprint, and the registering device for registering the correlation optical signal between the stored fingerprint and presented fingerprint to generate a signal to activate the device when, and only if, a positive correlation exists between the presented and the registered fingerprints. A two-stage holographic credit card using the "generalized matched optical filter", wherein the additional information for authorization is stored in the reference beam during the preparation of the said filter, the angular invariance is provided by the said means and the means of second-stage approvement, utilizing the existing banks communication lines, are also provided. A three-stage holographic credit card, using the "generalized matched optical filter", wherein the additional information for verification is stored in the reference beam during the preparation of the said filter, the angular invariance is provided by the said means, the means for bank's computer approving procedures, including the automatic feedback are provided, and the means of additional second-stage optical comparison are also supplied.

Multiple-Point Equalization in a Room Using Adaptive Digital Filters

Abstract: A method is presented for designing an equalization filter for a sound-reproduction system by adjusting the filter coefficients to minimize the sum of the squares of the errors between the equalized responses at multiple points in the room and delayed versions of the original electrical signal

Overview of design challenges for single phase unidirectional SAW filters

Abstract: A comprehensive discussion of the design synthesis challenges for single-phase unidirectional transducers (SPUDTs) is presented. The complexity of SPUDT filter design results from the fact that a SPUDT deliberately includes reflections internal to the transducer to cancel the effects of regeneration reflection. This destroys the validity of the impulse-response model which is the basis for all conventional SAW (surface acoustic wave) transducer designs. Although a recent generalization of the impulse response model includes effects of uniform internal reflections, it is of limited usefulness, because a high-performance SPUDT filter requires both weighted reflection and weighted transduction. Presented is a six-step SPUDT synthesis procedure which includes a new method for determining transduction and reflection weighting functions that satisfy a desired amplitude and phase response, achieve low insertion loss, achieve low triple transit, allow use of simple matching networks, and properly account for the interactions between transduction and reflection effects under matched conditions. Fundamental insertion-loss limitations for SPUDT filters are discussed and areas for future SPUDT research are outlined. Good experimental performance is demonstrated for a bandpass filter that uses a new SPUDT structure, the EWC/SPUDT, the geometry of which is also shown. >

Radiation clinical thermometer

Abstract: A radiation clinical thermometer includes a probe, a detection signal processing section, a body temperature operating section, and a display unit. A filter correction section for setting a correction value based on the transmission wavelength characteristics of a filter is arranged. The body temperature operating section receives infrared data, temperature-sensitive data, and the correction value from the filter correction section so as to calculate body temperature data.

Non-uniform multirate filter banks: theory and design

Abstract: The nonuniform, maximally decimated quadrature mirror filter (QMF) bank is introduced. It permits the use of nonuniform filter responses, which is more suitable for some applications. A necessary condition for alias cancellation is derived for the case where all the decimation factors are integer-valued. A special case of the two-channel nonuniform AMF system with nonintegral decimation factors is analyzed, and a technique for canceling aliasing and minimizing other distortions is presented and illustrated by a design example. >

Bit-serial realizations of a class of nonlinear filters based on positive Boolean functions

Abstract: It is shown that the function of a stack filter can be realized in k-step recursive use of one binary processing circuit. The time-area complexity of the proposed filter is O(k) as compared with O(2/sup k/) for stack filters. The proposed digital realizations are simple and modular in structure, and suitable for VLSI implementation. Analog/digital (A/D) hybrid realizations have the advantage that there is no need for an A/D converter array when the original signals come from an integrated sensor array. An experimental digital rank-order filter with a window size of three and arbitrary number of input bits is designed and implemented in a 3- mu m double-metal polysilicon gate CMOS process. The chip has been fabricated and measurement results are correct with a clock frequency of up to 110 MHz. >

Frequency multiplier with programmable order of multiplication

Abstract: This frequency multiplier circuit with variable multiplication order is of the type comprising a comb generator that receives, at input, a signal at the base frequency to be multiplied, and gives, at output, a composite pulse signal having a plurality of harmonic lines of the base frequency, said comb generator being followed by a pass-band filter that can be tuned selectively to one of these harmonic lines. The comb generator is formed by logic means having two complemented outputs, a synchronous input, the actuation of which controls the changing of these outputs from one logic state to the other, and a asynchronous input, the actuation of which controls, independently of the state of the synchronous input, the changing of these outputs to the states complementary to those generated by the actuation of the synchronous input. The base frequency signal is biased beforehand so that its excursion takes place around the transition voltage controlling the change from one logic state to the other, said signal being applied to the synchronous input of the logic means, and a first output of these means is connected to asynchronous input and the second output delivers said composite pulse signal to the the pass-band filter.

Filter plate, filter plate element, and filter comprising same

Abstract: A filter plate having a flow channel area on its main top surface, and liquid distribution and collection basins, each of polygonal shape, on its main bottom surface. Liquid inlet and discharge trough openings extend through the plate adjacent the respective distribution and collection basins, to communicate the basins on the main bottom surface of the plate with the flow channel area on the main top surface thereof. Such plates may be associated in opposedly facing pairs to form enclosed flow channels characterized by fluid flow patterns which are substantially uniform across the full transverse extent of the flow path and which facilitate the utilization of the full areal extent of the filter media employed therewith. Also described is a unitary filter element support which may be usefully employed in the filter. The filter of the invention may be advantageously employed for dewatering of aqueous biomass suspensions, desalting of proteins, removal of secreted metabolites from cellular suspensions, and the like.

Method and apparatus for protecting computer software utilizing coded filter network in conjunction with an active coded hardware device

Abstract: Filter networks are incorporated within a software protection hardware device which is plugged into a communications port of a computer which device will select bits or combinations of bits emanating from the communications port resulting from commands of a controlling software in use with the computer which is desired to be protected. The filter networks select the bits of a disguised predetermined control code which when matched with a stored reference code results in an output from the filter used to activate functions within the protection device. A stream of bits including a disguised predetermined control code issuing from the computer through the security device are compared with a stored reference code in a programmable memory. When a match occurs an output emanates providing an acknowledgment code to the computer indicating that the hardware device has been plugged in and is a proper one. The stored reference code can be provided by a programmable memory using an intermediate storage register between the programmable memory and the selection network. The intermediate storage register is clocked changing the reference code in a predetermined manner. Accordingly, the reference code is changed in accordance with what is stored in the programmable memory and by the content of an intermediate register at any given time, the effect of which is to continually change the reference code by clocking the intermediate register.

Filter assembly and cartridge therefor

Abstract: An assembly is provided of a filter bowl (10), a cartridge (12) and a head (11) in which the filter bowl (10) can be removed after it has descended from the filter head (11) through a distance corresponding to only a minor part of the length of the filter cartridge (12). The cartridge (12) is a push fit into a vertical port (52) in the filter head (11). Flange (18) of the cartridge (12) and a slotted buttress (44) of the bowl (12) establish a mechanical connection between the filter bowl (10) and the cartridge (12) so that the filter bowl (10) and the filter cartridge (12) are together mounted to and demountable from the filter head (11). The filter cartridge (12) having the support flange (18) that coacts with the buttress (44).

Practical performance of Bloom filters and parallel free-text searching

Abstract: Bloom filter technique of hashing finds several applications, such as in efficient maintenance of differential files, space efficient storage of dictionaries, and parallel free-text searching. The performance of hash transformations with reference to the filter error rate is the focus of this article.

Coherent operation of an array of diode lasers using a spatial filter in a Talbot cavity

Abstract: Coherent operation of an array of AlGaAs diode lasers was obtained by placing the array in an external cavity which made use of the Talbot self‐imaging effect to couple the laser diodes together. A spatial filter was required to suppress oscillation of the highest order mode of the array. This filter introduced no significant loss to the cavity mode, and the mode was observed to be stable up to the maximum rated drive current for the device.

Nonlinear filters for efficient shock computation

Abstract: A new type of methods for the numerical approximation of hyperbolic conservation laws with discontinuous solution is introduced. The methods are based on standard finite difference schemes. The difference solution is processed with a nonlinear conservation form filter at every time level to eliminate spurious oscillations near shocks. It is proved that the filter can control the total variation of the solution and also produce sharp discrete shocks. The method is simpler and faster than many other high resolution schemes for shock calculations. Numerical examples in one and two space dimensions are presented.

Subsampling time-domain digital filter using sparsely clocked output latch

Abstract: The plural-phase clocking signal used in a subsampling time-domain digital filter is partially blanked to generate a sparse clocking signal for a clocked data latch that decimates the output signal from the digital filter, to supply it at a subsampling rate as compared to the sampling rate of input signal to the filter. The blanking signal is generated from a counter that counts occurrences of pulses in the plural-phase clocking signal, which counter comprises a ripple-carry adder and another clocked data latch arranged to accumulate successive unit values. This procedure guarantees correct timing of clocking signal for the output latch vis-a-vis the plural-phase clocking signal used in the preceding time-domain digital filter despite the time taken for carry ripplethrough in the counter adder. Digital hardware is conserved by blanking only one phase of the plural-phase clocking signals.

Adaptive IIR filtering using parallel-form realizations

Abstract: Several parallel-form adaptive IIR (infinite impulse response) filters are presented, including a frequency-domain implementation based on the discrete Fourier transform and a recursive frequency-sampling structure. The performance of the frequency-domain adaptive IIR filter is investigated in a system identification application, which includes an analysis of its modeling capabilities and a discussion of the mean-square-error performance surface. Computer simulation results are presented to illustrate the robust convergence properties of the adaptive algorithm and to demonstrate the stability of the filter. >

Disk drive breather filter

Abstract: The magnetic disk drive chemical breather filter of the present invention affords protection with respect to chemical vapors and gases in addition to trapping particulate pollutants. The chemical filter as described, protects against both organic vapors and inorganic gases. In addition particulate filters are interposed between the chemical filters and both the exterior atmosphere and internal atmosphere. The combined filter is isolated from both external and internal atmosphere by extended length diffusion passages. Both difffusion passages are composed of multiple parallel paths to prevent the blockage of any single path from impairing the functioning of the filter. Chambers formed at each side of the combined filter medium and access thereto by the diffusion passages at the center of one chamber and the periphery of the other enables the length of the air passage through the filter medium to be equal irrespective of the portion of the filter through which the air flow passes. Using an activated carbon fabric chemical filter and coplanar multiple diffusion paths, a low profile, low cost filter assembly is achieved. The use of ultrasonic welding of the parts eliminates connector devices and adhesives as sources of contamination.

The problem of on-chip automatic tuning in continuous-time integrated filters

Abstract: A discussion is presented of the most important and difficult aspect of the design of fully integrated continuous-time filters: continuous, real-time, on-chip tuning of filter parameters against errors caused by such factors as fabrication tolerances, changes in operating conditions, parasitic effects, and aging. The origins of the errors in filter parameters are pointed out, and the generally adopted methods for automatic error correction are discussed. These methods are a phased-locking loop for tuning of frequency parameters and a magnitude-locking loop for maintaining the transfer characteristic's shape. Guidelines are given to aid the designer in avoiding the most prevalent pitfalls, and an illustrative example is presented which incorporates the ideas and concepts discussed. >

Stage lighting apparatus

Abstract: The disclosed stage lighting apparatus includes a constant-direction beam forming unit and an adjustable beam redirector for aiming the beam at a wide range of locations varying in azimuth and elevation, and programmable remote-control equipment for the various adjustments of the beam-forming unit and the beam redirector. The beam-forming unit comprises a lamp and a heat-absorbing ellipsoidal reflector acting with the lamp to provide a beam; a heat-extracting filter in the path of the beam comprising a chamber containing circulated liquid that absorbs infra-red and a dichroic filter that reflects infra-red and is cooled by the circulated liquid of the chamber; an adjustable filter in the path of the beam comprising three elongated mutually overlapping subtractive color filters and a neutral brightness control filter, each filter having densities varying from clear to a maximum; an adjustable beam shaper; and adjustable beam-focussing lenses, all of which provides a constant-direction beam, the beam then being adjustably directed to the stage.

Modeling, analysis and design of distributed power systems

Abstract: A distributed power supply system featuring two cascaded stages of parallel-module switching regulators is analyzed. Analysis and design of cascaded regulators are presented, taking into account the dynamic impedances of the cascaded stage. The design of a noninteractive EMI (electromagnetic interference) filter for the intermediate bus is discussed. Design considerations for parallel modules are also outlined. >

Auditory filter characteristics and consonant recognition for hearing‐impaired listeners

Abstract: To examine the association between frequency resolution and speech recognition, auditory filter parameters and stop‐consonant recognition were determined for 9 normal‐hearing and 24 hearing‐impaired subjects. In an earlier investigation, the relationship between stop‐consonant recognition and the articulation index (AI) had been established on normal‐hearing listeners. Based on AI predictions, speech‐presentation levels for each subject in this experiment were selected to obtain a wide range of recognition scores. This strategy provides a method of interpreting speech‐recognition performance among listeners who vary in magnitude and configuration of hearing loss by assuming that conditions which yield equal audible spectra will result in equivalent performance. It was reasoned that an association between frequency resolution and consonant recognition may be more appropriately estimated if hearing‐impaired listeners’ performance was measured under conditions that assured equivalent audibility of the speech stimuli. Derived auditory filter parameters indicated that filter widths and dynamic ranges were strongly associated with threshold. Stop‐consonant recognition scores for most hearing‐impaired listeners were not significantly poorer than predicted by the AI model. Furthermore, differences between observed recognition scores and those predicted by the AI were not associated with auditory filter characteristics, suggesting that frequency resolution and speech recognition may appear to be associated primarily because both are degraded by threshold elevation.

HDTV Sub-band coding using IIR filter bank

Abstract: A technique for the sub-band decomposition and reconstruction of video signals is disclosed. In an illustrative embodiment of the present invention, each field of a video signal is decomposed into sub-bands utilizing a polyphase filter bank unit including an infinite impulse response allpass filter with coefficients that are powers of two. To reconstruct the original image, an FIR is utilized which approximates an IIR allpass filter This eliminates the need for a full field memory in the reconstruction process.

Multipoint modem system having fast synchronization

Abstract: A multipoint data modem communication system (10) includes a master modem (12) and a plurality of remote modems (14, 16 and 18). During an initial, remote-to-master transmission, a relatively long training sequence is transmitted and receiver parameter and equalizer coefficients are stored in a storage unit (156) in the master modem (12). During subsequent transmissions a relatively short training sequence which synchronizes the master modem receiver timing and also identifies the transmitting remote modem is applied. In the master modem an interpolation filter based on a ninth order Lagrange interpolation formula is located between an analog-to-digital converter (84) and a band-pass filter (92). Coefficients for the interpolation filter are calculated using a residual time shift value which is computed using a DFT calculator (96) which is coupled to a phase segment detector (142) and a phase-to-time-shift converter (146).

Monolithic ceramic filter with bandstop function

Abstract: of the Disclosure A ceramic filter (144,118) includes a multiple zero bandstop filter function. The ceramic filter has a dielectric block (210) with top and bottom surfaces and at least two holes (221-227), extending from the top surface toward the bottom surface of the block. The block (210) is selectively covered with a conductive material to provide a transmission line resonator for each of the two holes. The filter also includes an input electrode (214) coupled to the dielectric means at a predetermined distance form one first hole (201), and an output electrode (216) coupled to the dielectric means at a predetermined distance from another hole (207). Finally, conductive plating (240), in the form of a transmission line, is contiguously disposed on the dielectric means adjacent the two holes and coupled thereto to provide a bandstop filter function with a zero represented at each hole.

Inclusion of filter modulation in synthetic-discriminant-function construction.

Abstract: A technique in which the filter modulation is included in the synthesis of a synthetic-discriminant-function matched spatial filter (SDF MSF) is presented. In the filter synthesis, a system of simultaneous nonlinear equations is solved with an iteration procedure. A computer simulation of the new method using thresholded images of the Space Shuttle over a range of aspect angles was performed for phase-only filters (POFs) and binary-phase-only filters (BPOFs). The filters constructed are capable of obtaining the specified peak-correlation response to within 1% with a high signal-to-clutter-ratio for the one-class problem, the two-class problem, and the multilevel problem. In contrast, conventional projection SDF POFs and BPOFs are unable to produce the desired peak-correlation response.

Filter condition indicator having moveable sensor and aggregate flow counter

Abstract: A fluid filter monitoring system. A flow switch positioned in juxtaposition to a fluid flow path monitors fluid flow and provides an indication during those time periods when fluid is flowing at a rate exceeding a predetermined flow rate through the flow path. A monitoring circuit coupled to this indication provides various audible and/or visible indicators corresponding to detected conditions. The preferred design includes a timer for monitoring the time duration since the filter was installed as well as monitoring the time duration water or other fluids are flowing through the filter. Adjustably settable visible and/or audible indications are provided to indicate when the filter is reaching the end of its useful life as well as when this life period has been exceeded.