A tuneable, bandwidth-adjustable solid-state filter
Tuneable adjustable solid state bandwidth filter using N path system for low pass to bandpass filter transformation
Glaser, A. B.↗
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Stochastic processes and filtering theory
Book on stochastic processes and filtering theory covering probability theory, Markov processes, linear and nonlinear filters, etc
Jazwinski, A. H.↗
Modifications to a vacuum assisted filtering device to minimize contamination
High purity filter unit saves time and expense in laboratory operations and improves purity of liquids processed. Any but most viscous liquids are processed by modified unit equipped with appropriate filter medium. Unit's use eliminates much glassware cleaning tedium.
Gaudiano, S.↗
Linear, Kalman, and epoch state filtering techniques Quarterly progress report, 1 Dec. 1970 - 30 Apr. 1971
Numerical analyses of error covariance matrix in linear filtering problem, computational errors in Kalman filtering, and coasting flight equations
Source record↗
Filter cassette for high volume air sampler
Filter cassette eliminates or substantially reduces contamination of filter media by extraneous material and facilitates handling.
King, R. B.↗
Acousto-optic filter for electronic laser tuning
Electronically tunable lithium niobate filter utilizes acoustic-optic diffraction for tuning laser to desired frequencies. Filter placed inside laser cavity diffracts incident optical signal of one polarization into orthogonal polarization by collinearly propagating acoustic beam to desired wavelength.
Harris, S. E.↗
Design of recursive digital filters having specified phase and magnitude characteristics
A method for a computer-aided design of a class of optimum filters, having specifications in the frequency domain of both magnitude and phase, is described. The method, an extension to the work of Steiglitz, uses the Fletcher-Powell algorithm to minimize a weighted squared magnitude and phase criterion. Results using the algorithm for the design of filters having specified phase as well as specified magnitude and phase compromise are presented.
King, R. E.↗
Electronically tuned optical filters
A detailed account is given of efforts to develop a three layer, polychromic filter that can be tuned electronically. The operation of the filter is based on the cooperative alignment of pleochroic dye molecules by nematic liquid crystals activated by electric fields. This orientation produces changes in the optical density of the material and thus changes in the color of light transmitted through the medium. In addition, attempts to improve materials and devices which employ field induced changes of a cholesteric to a nematic liquid crystal are presented.
Castellano, J. A.↗
JPL P/N 71 x 12400 etched disc filter
The results are presented of a glass bead test conducted with a JPL P/N 71 x 12400 etched disk filter assembly to determine the largest diameter spherical glass bead that would transmit through the filter assembly. It was found that the largest glass bead transmitted was 16 microns in diameter.
Source record↗
Lunar laser ranging data deposited in the National Space Science Data Center: Filtered observations for September 1969 through June 1970 and unfiltered photon detections for July through December 1970
The technique of laser ranging to a reflector fixed on the lunar surface is discussed. The causes for initial low rate of data acquisition are explained. The documentation to be used in conjunction with the deposition of the filtered data in the National Space Science Data Center are documented. Filtered data obtained during laser operations between the McDonald Observatory and the reflector at Tranquility Base during the interval September 1969 through June 1970 are presented. The unfiltered photon detections for the succeeding six months are examined.
Mulholland, J. D.↗
Discrete square root filtering - A survey of current techniques.
Current techniques in square root filtering are surveyed and related by applying a duality association. Four efficient square root implementations are suggested, and compared with three common conventional implementations in terms of computational complexity and precision. It is shown that the square root computational burden should not exceed the conventional by more than 50% in most practical problems. An examination of numerical conditioning predicts that the square root approach can yield twice the effective precision of the conventional filter in ill-conditioned problems. This prediction is verified in two examples.
Kaminskii, P. G.↗
The estimation of the constituent densities of the upper atmosphere by means of a recursive filtering algorithm.
The structure of the upper atmosphere can be indirectly probed by light in order to determine the global density structure of ozone, aerosols, and neutral atmosphere. Scattered and directly transmitted light is measured by a satellite and is shown to be a nonlinear function of the state which is defined to be a point-wise decomposition of the density profiles. Dynamics are imposed on the state vector and a structured estimation problem is developed. The estimation of these densities is then performed using a linearized Kalman-Bucy filter and a linearized Kushner-Stratonovich filter.
Mcgarty, T. P.↗
Nonlinear filtering for random signals in statistically unknown noise.
Natural and effective formulation of the filtering problem involved in satellite orbit determination, aircraft navigation, and missile tracking. The problem arises because the environment of the sensor keeps changing from time to time, and it is quite impractical and sometimes impossible to collect the statistical data of the noise incurred in the observation. Computable filtering equations are deduced. The idea of invariant imbedding along with stochastic differential calculus is used to derive differential equations for the optimal estimate.
Loo, J. T.↗
Encoding and decoding of color information using two-dimensional spatial filtering.
Spatial frequency encoding is described as it applies to both photographic and television systems. In each case, color separations amplitude modulate spatial frequency carriers. The photographic system separates the carriers in the two-dimensional Fourier transform plane using coherent optics; the television system employs a two-dimensional electrical filter to perform the same separation. These filters are synthesized so that the two-dimensional bandwidths of the television camera are used efficiently. Nonlinear processing techniques are also described to minimize crosstalk between channels.
Schaefer, L. F.↗
Tilting-filter measurements in dayglow rocket photometry.
A rocket-borne photometer containing two tilting-filter channels for the measurement of the forbidden OI 6300-A and 5577-A emission lines in the day airglow is described. The results of one flight substantiate the employment of tilting filters to determine accurate corrections for background continuum and provide reliable height profiles of emission intensity down to approximately 90 km. Discussions on the calibration of the instrument and its baffling against sunlight are also presented.
Schaeffer, R. C.↗
Digital notch filter
Filter determines whether time period of incoming signal matches time preset in filter. When signals do not match, high or low frequency deviation reading is displayed digitally.
Meers, B. Z., Jr.↗
Improved photographic prints with a linear radial transmission filter
Linear Radial Transmission Filter (LRTF) is easy to use and yet results in prints which depict more information contained in negative than can be shown by direct printing. LRTF is optical-quality filter which has maximum transmission in center and linear drop in transmission radially out from center.
Weinstein, L. M.↗
Extended range harmonic filter
Two types of filters, leaky-wall and open-guide, are combined into single component. Combination gives 10 db or greater additional attenuation to fourth and higher harmonics, at expense of increasing loss of fundamental frequency by perhaps 0.05 to 0.08 db. Filter is applicable to all high power microwave transmitters, but is especially desirable for satellite transmitters.
Jankowski, H.↗