Showing papers on "Filter (video) published in 1970"

Estimating Optimal Tracking Filter Performance for Manned Maneuvering Targets

Abstract: The majority of tactical weapons systems require that manned maneuverable vehicles, such as aircraft, ships, and submarines, be tracked accurately. An optimal Kalman filter has been derived for this purpose using a target model that is simple to implement and that represents closely the motions of maneuvering targets. Using this filter, parametric tracking accuracy data have been generated as a function of target maneuver characteristics, sensor observation noise, and data rate and that permits rapid a priori estimates of tracking performance to be made when maneuvering targets are to be tracked by sensors providing any combination of range, bearing, and elevation measurements.

On the interaction of roundoff noise and dynamic range in digital filters

Abstract: The interaction between the roundoff-noise output from a digital filter and the associated dynamic-range limitations is investigated for the case of uncorrelated rounding errors from sample to sample and from one error source to another. The required dynamic-range constraints are derived in terms of L p norms of the input-signal spectrum and the transfer responses to selected nodes within the filter. The concept of “transpose configurations” is introduced and is found to be quite useful in digital-filter synthesis; for although such configurations have identical transfer functions, their roundoff-noise outputs and dynamic-range limitations can be quite different, in general. Two transpose configurations for the direct form of a digital filter are used to illustrate these results.

Variable Metal Mesh Coupler for Far Infrared Lasers

Abstract: In a far infrared molecular laser the traditional pierced output mirror has been replaced by an infrared interference filter, consisting of two metal mesh reflector grids. By adjusting the spacing between the two parallel grids, the reflectance of the filter can be varied. Theory and experiment of this variable reflector are presented. It allows convenient optimization of the coupling conditions of a laser for maximum power output. In contrast to hole coupling, the interference filter provides uniform coupling over the entire cross section of the reflector. This reduces the diffraction losses and improves the angular distribution of the output beam. The variable reflector has also been used to determine the linear gain of the laser.

CaMoO4 ELECTRONICALLY TUNABLE OPTICAL FILTER

Abstract: The paper describes a CaMoO4 transmission‐type acousto‐optic filter. Tuning from about 6700 to 5100 A is obtained by changing an acoustic frequency from 40 to 68 MHz. The filter bandwidth is 8 A at an f/6 aperture. 95% transmission is obtained at an acoustic power density of 69 mW/mm2.

A Simple Adaptive Equalizer for Efficient Data Transmission

Abstract: A small and relatively inexpensive automatic equalizer has been developed for use with a vestigial sideband AM data set presently utilized to provide a high-speed Bell System voiceband data service. The equalizer uses a transversal filter structure comprising a tapped analog delay line with a variable-gain circuit associated with each tap. Its operation is adaptive in the sense that the tap-gain-adjustment information is derived from the received data, so that the tap gains are continuously optimized. A number of adaptive tap-gain-adjustment algorithms and transversal filter realizations were considered. The algorithms range in order of implementation complexity from "zero forcing," involving binary correlation, to "mean square," which requires linear correlation. The transversal filter realizations vary from an early scheme, which accomplished the variable-gain function with up-down counters controlling a switchable resistive ladder network, to an all-digital approach, where the analog delay line is replaced by shift registers and the variable-gain function is achieved with binary multipliers. Although the all-digital approach, using the mean-square algorithm and implemented with large-scale integration, will undoubtedly be the best choice in the near future, the equalizer to be described was selected on the basis of its being the cheapest to implement at the present time. The equalizer uses a modified zero-forcing tap-gain-adjustment algorithm, which is no more costly to implement than the zeroforcing algorithm, but which has superior convergence properties in the presence of severe distortion. The variable-gain function is achieved by means of a field-effect transistor (FET) used as a variable resistance. A single operational amplifier is used both to control the resistance of the FET and to provide feedback necessary to insure precise circuit performance without requiring close tolerances on the FET characteristics.

Apparatus and method for removing fumes from the space above a cooking appliance

Abstract: A self-contained, mass-producible fume hood or canopy for mounting in the space above a cooking appliance, so that fumes which pass upwardly into the hood will be removed from the room. Supply air from the exterior of the room is supplied to the hood and is fed through a baffle and throat apparatus toward filter and exhaust means, such baffle and throat apparatus being horizontally, vertically and angularly adjustable. The direction of supply air flow from the baffle and throat apparatus is caused to be substantially perpendicular to the filter, and the supply air first strikes the filter at an intermediate region as distinguished from the upper and lower regions. The relationships are caused to be such that some of the supply air passes directly through the filter, whereas other supply air rolls or vortexes (swirls) upwardly and downwardly. Upper and lower deflector means are provided to cause the upwardly and downwardly rolling supply air to return to the filter means for exhaust therethrough. The upper vortex is caused to be very large, whereas the lower is small. Means are provided to direct part of the supply air horizontally below the adjustable baffle and throat apparatus, thus entraining fumes and directing the same toward the filter means. Inclined means are provided to deflect fumes into the region above the lower deflector means. Trough and heater means are provided to receive grease from the filter, and means are provided to remove condensed water. The method of the invention relates to the critical air velocities, directions, and paths adapted to effect a substantially 100 percent removal of fumes from the region above the cooking appliance, with very little removal of cooled or heated air from the room.

Sampled data filter

Abstract: A sampled data filter is disclosed comprising a plurality of amplifiers interconnected by delay units and feedback resistors. Each delay unit comprises the cascade connection of actuable switches and storage capacitors. The values of the capacitors and feedback resistors are preselected to obtain a desired transfer function and to nullify the effects of residual capacitor charge.

Analysis of Electrothermal Integrated Circuits

Abstract: Electrical and thermal interactions in silicon integrated circuits provide a means for realizing large effective time constants and, correspondingly, low cutoff frequencies in filters. This paper describes a method of analyzing the behavior of a general configuration of lumped or distributed heaters and sensors in an integrated circuit. The method yields results that are amenable to computer evaluation, and that also indicate how heaters and sensors should be shaped to obtain a particular type of response. A practical synthesis procedure is given for filter applications, and experimental results are presented that show close agreement with calculated values for examples of both analysis and synthesis of filters.

Analysis of a dye laser tuned by acousto‐optic filter

Abstract: A model of a dye laser electronically tuned by an acousto‐optic filter is analyzed. Chirping modes are superposed to yield a steady‐state periodic solution which predicts a shift of the spectrum to the high end of the filter band and appreciable spectral narrowing. For the example considered, the theory predicts a narrowing factor of 100.

Filter cartridge and pack therefor and method of making same

Abstract: An annular filter pack of longitudinally folded filter paper has a plurality of longitudinally spaced bands of adhesive resin disposed around the inside periphery so as to accurately position the inside folds and dimensionally stabilize the filter pack. The filter pack is incorporated into filter cartridges which may be used to filter a variety of fluids.

Screen filter pack and method for making same

Abstract: The filter is constructed of superimposed corrugated screens, each of which has a plurality of flattened areas of a predetermined width at the level of the apexes of the corrugations and extending transversely to the latter. One screen may be superimposed on another screen with its flattened areas in registry with those of the other screen, but with the flattened area of both screens being disposed most remotely from each other, so that the two screens define a plurality of passages of said predetermined width extending between each pair of screens and through the corrugations. Into these passage bars may be inserted for support of the screens. Such bars may be of a magnetizable material and magnetized to attract metallic particles in the gas or fluid to be filtered through the screen. Additional pairs of screens may be stacked upon the first pair to make up a filter pack.

Etched inductance bandpass filter

Abstract: A bandpass filter of one or more stages using etched inductors and designed for use in the VHF or UHF ranges is disclosed. Three etched inductors are used in each stage, and a variable capacitor is used to tune the stage. Alternatively, the variable capacitor may be replaced by a fixed capacitor, and a variable inductor may be substituted for one of the fixed inductors. Coaxial cable may be used to couple stages together. A modified filter stage is also disclosed to simplify tuning procedures when filters having three cascaded stages are assembled.

Filter-silencer for pneumatic devices

Abstract: A filter-silencer for pneumatic devices such as air valves, cylinders and the like of the type including a porous filter of a sintered metallic mass wherein, upon clogging of the filter and reduction of the air flow through the exhaust port for the corresponding air device, an auxiliary exhaust path is established which precludes the build-up of excessive back pressures in the pneumatic device and which also provides an audible warning signal indicating the need for servicing of the filter-silencer to restore the porous filter to its normal and intended functional state.

Automatic tracking filter

Abstract: An automatic tracking filter for use in conjunction with fluid flowmeters automatically locks onto the largest signal in a given frequency spectrum. The filter comprises a narrow band-pass filter having input and output filter circuits (e.g., a low-pass and a high-pass filter) connected in series. The output of the input filter circuit is combined in a control circuit with the input signal to generate an error signal which is used to tune each of the filter circuits to the input signal. In one embodiment disclosed the filter sections are two-pole active R-C filters in which a field-effect transistor is used as a voltage variable resistor.

A New Tunable Filter with a Very Narrow Pass-Band

Abstract: Fabry-Perot interferometer series as tunable optical narrow passband filter with high spectral and angular resolution, discussing performance in solar magnetograph

Wavelength selective mirror systems

Abstract: Polychromatic beams are separated into component colors or wavelength bands by wavelength selective filters combined with a beamsplitter. These filters are arranged on three sides of a cubic space, with a beamsplitter on the diagonal. The space may be air or a cube of transparent material, such as glass. If the beam is to be split into more than three colors, a second cube is used with additional beamsplitters. At least one filter which receives a beam split by the beamsplitter, either the filter which receives the transmitted beam or the reflected beam, must be a reflecting filter which reflects the wavelengths that are not transmitted. Preferably such filters are interference filters. Two or three reflecting filters give better energy utilization. The beamsplitters may be chromatic or achromatic. Phase retardation plates compensate to polarization effects. The invention is particularly useful with electrical signal detectors for readouts for coded marks using photoluminescent components forming the code.

FEN filter design using tantalum and silicon integrated circuits

Abstract: An economical approach to integrated active RC filter design is described. Complex filter networks are broken down into a series of cascadable second-order filter sections consisting of tantalum thin-film RC networks and semiconductor integrated operational amplifiers. Two building blocks are available for any desired frequency within a decade and for any desired filter function (e.g., low-pass, high-pass, band-pass, band-reject, all-pass, etc.). One building block is for low Q realizations and contains one amplifier; the other is for high Q realizations and contains two. The considerable versatility of this approach is obtained by 1) a network synthesis approach based on decomposing a given second-order function into a low Q asymptotic approximation of this function in cascade with an active frequency emphasizing network and 2) by the characteristics of tantalum and silicon integrated circuits.

Compressors and expanders for noise reduction systems

Abstract: The invention concerns noise reduction systems and compressors and expanders therefor in which the overall characteristic is formed by combining the output of a further path additively or subtractively with the output of a main, straight-through path, the further path including a filter and limiter. In this improvement the filter is essentially all-pass at low levels and only becomes high- pass or low-pass at higher levels. At low levels noise reduction is therefore wide-band. Applicable to tape and disc audio noise reduction.

Method and apparatus for personal identification

Abstract: A method and apparatus for creating an encoded fingerprint card which consists of a hologram of a fingerprint created by a main illuminating beam and a reference beam on a sensitive photographic plate and the use of the encoded fingerprint in a matched filter correlator in real time wherein the fingerprint of a subject can be introduced into the system and correlated with the encoded information to verify identity between the original encoded information and the person claiming identity therewith The system includes a means for creating relative motion between the fingerprint transform image and the transform plane filter in the form of a hologram to insure proper alignment at some place between said image and said filter to produce light output correlation peaks even when the image or the filter or both are mechanically misaligned

Filter with rotating backwash selector

Abstract: A filter assembly having a plurality of individual filter units, each including an impervious outer skirt surrounding an elongated filter member. A fluid-solid mixture is supplied to the filter units in a direction to flow radially inwardly through the filter member. Rotatable backwash arms are disposed adjacent the opposite ends of the filter units for sequentially and progressively permitting backwashing thereof. Tne backwash fluid flows radially outwardly through the filter members for removing the collected solid material. The backwash arms are connected to inlet and outlet pipes, with the inlet pipe being connected to an external source of separate backwash fluid. The backwash arms are rotatably driven by means of external drive system which includes disconnectible means for enabling one end of the filter housing to swingable move into an open position, carrying with it the backwash arm connected thereto, for permitting servicing of the individual filter units.

Design of hybrid integrated-filter building blocks

Abstract: An economical approach to integrated active RC filter design is described. Complex filter networks are broken down into a small family of cascadable second-order filter building blocks consisting of tantalum thin-film RC networks and semiconductor, integrated, operational amplifiers. The same building blocks are used for any desired filter configuration such as low-pass, high-pass, or bandpass filters, all-pass networks, notch filters, etc. Therefore, they possess the uniformity necessary for high-production quantities and batch processing, and consequently, benefit from the economical advantages that go with these methods.

Method and apparatus for clarifying liquids

Abstract: Method and apparatus for clarifying a liquid passed through a filter bed having relatively fine and relatively coarse layers, in which a polyelectrolyte is introduced into the liquid before it is introduced into the filter to flow from the coarse to the fine layer, migration of coarse to fine particles is prevented by one foraminous barrier and breakup of the fine uppermost layer is prevented by another foraminous barrier.

Tobacco smoke filter

Abstract: A frangible tobacco smoke filter composed of a resilient tubular casing and a unit consisting of interconnected, opposed seals. When the smoker applies pressure to the casing, the unit is broken thereby allowing for passage of the tobacco smoke through a smoke-treating medium contained within the casing.

Vibration-monitoring systems

Abstract: A vibration-monitoring system for use with a three-shaft gas turbine engine. Vibration from the engine is picked up by two electrical transducers and transmitted to a filter network. The filters produce three electrical outputs in three separate frequency bands, each of which corresponds to the frequency band of the vibration produced by a respective one of the shafts. The vibration produced by each shaft can thus be separately indicated.

Gas sampling apparatus

Abstract: Gas-sampling apparatus for sampling a dirt- and moisture-laden gas stream, such as blast-furnace top gas, cleaning the gas and delivering it to a gas analyzer employs parallel sampling probes and associated filter units to permit continuous alternate sampling and cleaning of the filters by back-flushing The apparatus automatically ceases sampling whenever a foreign gas is introduced into the gas stream being sampled

Pcm data transmission system

Abstract: An improved pulse code modulation (PCM) data transmission system whose pulse amplitude modulation (PAM) stage contains a sampled data or scanning filter for the analog data which is scanned at a frequency fp which is a whole number multiple of the frame frequency fR of the PCM system, and in which quasi four-wire transmission is provided between the PCM system and the connected users or parties without using a four-wire terminating set, whereby only one sampled data filter need be provided both for receiving and transmitting data. According to the invention circuit means are provided for coupling the received transmitted PCM signals, at the scanning frequency fp, to the same sampled data filter utilized to filter the sampled analog signals from the respectively connected users, and further means are provided at the output of the sampled data filter for shifting the center frequency of the carrier-frequency bands utilized for the transmission of data from the PAM stage to the respective connected users so that after further scanning of these carrierfrequency bands at the scanning frequency fp the resulting frequency bands will not fall into the periodic pass bands of the sampled data filter. If a digital sampled data filter is utilized, the received PCM data signals may be fed directly thereto without decoding. Alternatively, if an analog sampled data filter is utilized, then the received PCM data signals must be decoded into PAM signals before they are fed to the sampled data filter.