Filter Setup Research Articles

Color coding of spatial frequencies: quality criteria, illustrations

The question of what can be called a 'good' spatial frequency color coding is discussed with the help of five quality criteria: color purity, sensitivity, selectivity, resolution and luminosity. The first two criteria imply that in a spatial frequency filter setup with the monochromatic point source replaced by a white point source, the mask should be transparent on one (theoretically extremely fine) curve only. Such black and white masks have been tested experimentally, but they yield poor resolution and luminosity. The effect of the curve thickness is examined and new versions of such masks are proposed. Their performance is compared to those of other types of masks. A new simple interference mask yielding saturated colors by multiple beam interference is introduced.

An Easy Tunable Stepped Coupled Lines Filter

A stripline bandpass filter setup consisting of two stepped coupled lines is presented, with special emphasis being given to practical realization. The theoretical design of the filter is based on the known synthesis of directional couplers and is outlined briefly. Practical setup of the filter, together with a simple tuning mechanism, is described in detail. Measurements performed show good agreement with theoretical results.

In-beam γ-ray studies of complex band structures and of isomeric states in 152, 153Dy nuclei

The high-spin level structures of 152Dy and 153Dy were studied experimentally with 154, 155Gd(α xnγ) in-beam reactions, and for 152Dy also with 144, 146 Nd( 12C, x nγ) reactions. The experiments included measurements of singles γ-ray and conversion-electron spectra, γ-ray angular distributions and E γ - t and E γ - E γ - t coincidences. A multiplicity filter set-up was used to study the feeding and decay of isomeric states in 152Dy. In 152Dy about twenty so far unknown levels were found, including two high-spin isomeric states with T 1 2 ≈ 60 and ≈ 13 ns at excitation energies E x ≈ 5.04 and 6.08 MeV, respectively. These states are compared with recent calculations on yrast traps. The level scheme of 153Dy contains 28 levels up to E x = 4.1 MeV and J π = ( 37 2 +) . Band structures in both nuclei are discussed in comparison with other N = 86 and N = 87 isotones.

Robust bayesian estimation for the linear model and robustifying the Kalman filter

Starting with the vector observation model y = Hx + v , robust Bayesian estimates \hat{x} of the vector x are constructed for the following two distinct situations: 1) the state x is Gaussian and the observation error v is (heavy-tailed) non-Gaussian and 2) the state is heavy-tailed non-Gaussian and the observation error is Gaussian. Bounds with respect to broad symmetric non-Gaussian families are derived for the error covariance matrix of these estimates. These one-step robust estimates are then used to obtain robust estimates for the Kalman filter setup y_{k}= H_{k}x_{k}+ v_{k}, x_{k+1}=\Phi_{k}x_{k}+w_{k} . Monte Carlo results demonstrate the robustness of the proposed estimation procedure, which might be termed a robustified Kalman filter.

A THEORETICAL ANALYSIS OF A COMPRESSED-TIME CORRELATOR FOR SIGNAL DETECTION

The theoretical problems of a compressed-time correlator are investigated from the viewpoint of signal detection. Through discussion of the LMF arid PR signals, some useful conclusions and basic formulas concerning the output signal, spectrum structure, Doppler filter set-up, noise background, SNE gain and signal envelope smoothing are obtained. As a consequence, it has been possible to design an improved sound pulse-compression receiver.

Experimental Demonstration of Optical Sectioning by Spatial Filtering and Its Possible Use in Transmission of Three-Dimensional Pictures

A method of spatial filtering which allows one to obtain optical cross sections of a three-dimensional object is demonstrated. The essence of the method is to photograph the object, which is illuminated by a fine pattern of light, with a camera of limited depth of field. The fine pattern appears in focus on the photographic negative of a selected cross section of the object while the foreground and background parts of the object are blurred. The photographic transparency is then placed in a standard spatial filtering setup, and the desired cross section thus obtained. The optical sectioning technique for generating three-dimensional images will then be compared according to information density with holographic and fly's eye lenslet methods.