In this paper, a simple adaptive notch filter (ANF) scheme for reducing RFI over CAP/QAM-based VDSL systems is proposed. To alleviate the spectral null caused by notch filtering, a null reshaping scheme is introduced between the normal ANF and the decision feedback equalizer (DFE). The proposed filter scheme can control the width and depth of the null. The shallow and narrow null obtained by null reshaping reduces the loss of signal components and consequently improves the mean square error (MSE) at the output of the equalizer. The proposed null reshaping scheme also enables the infinite impulse response (IIR) type constrained ANF to have a smaller pole contraction factor α. This results in a fast convergence property in RFI frequency estimation with a recursive prediction error (RPE) algorithm. The performance variations of the proposed null reshaping are investigated with varying filter parameters. Compared to the conventional ANF, simulation results show that, at the expense of small system complexity, the proposed structure yields a 2-3 dB MSE gain and a fast convergence property for RFI estimation.

Beam reconfiguration by structural reconfigurable antenna, such as the small multi-panel reconfigurable reflector antenna, has an aspect of great concern, that is the effects due to the use of a number of small panels to form the reflecting surface. It is thus a matter of great interest to numerically investigate all possible factors affecting the performance of this type of antenna such as: neighboring panels blocking, diffraction. The "null-field hypothesis" and PTD are employed to account for the effects of both phenomena on the main beam steering ability and the cross-polar level. In addition, the transformation of the polygonal flat domains into the square domains is applied in calculating the PO radiation field due to the various irregular polygonal flat sections of the arbitrary initial approximate reflector e.g., the flat circular reflector and the paraboloidal reflector. It is found that the main contribution to the total cross polarization is depolarization due to the finite size of the panels. The maximum cross-polar gain predicted using PTD is around -30 dB. The blocking effect has minor influence on cross-polarization. Both effects cause distortion on the co-polar pattern for the observer far from boresight but blocking has more influence than edge diffraction. Both effects have minor influence on the co-polar gain. The co-polar gain has variation of less than or equal to 0.07 dB in the flat case and 0.16 dB in the paraboloid case.

It is the purpose of this paper to review the generation of quantized voltage steps in Josephson-junctions, and also the recent practical application of these precise measurements. A 10-V Josephson-junction-array-voltage standard system has been established with a Josephson-junction-array, a phase-locked millimeter wave, and a precise null-detection system. Based on these technologies, the AC Josephson effect has been applied to other precise measurements such as DC error voltage of a multi-integrating analog-to-digital converter and for a pulse-width-modulation type precise voltage calibrator.

Diffraction pattern functions of an E-polarized scattering by a wedge composed of perfectly conducting metal and lossless dielectric with arbitrary permittivity are analyzed by applying an improved physical optics approximation and its correction. The correction terms are expressed into a complete expansion of the Neumann's series, of which coefficients are calculated numerically to satisfy the null-field condition in the complementary region.

This paper proposes a time-interval data model in which all temporal representation and operations can be expressed with time intervals. The model expresses not only real time intervals, in which an event exists, but also null time intervals, in which an event is suspended. We model the history of a real-world event as a composite time interval, which is defined in this paper. Operations on the composite time intervals are also defined, and it is shown how these operations can be used to express temporal constraints with time intervals.

Irreducible components of canonical graphs for second order spectral null constraints at a rational submultiple of the symbol frequency fsk/n are studied where fs is the symbol frequency. We show that if n is prime then a canonical graph consists of disjoint irreducible components. We also show that the number of irreducible components of a canonical graphs is finite if n is prime. For the case n = 2 and p O mod n, all aperiodic irreducible components are identified explicitly where p is a parameter of a canonical graph.

Signal processing antennas have been studied not only for interference suppression but also for high-resolution estimation of radio environment such as directions-of-arrival of incident signals. These two applications are based on the common technique, that is, null steering. This tutorial paper reviews the MUSIC algorithm which is one of the typical high-resolution techniques. Examining the eigenvector beam patterns, we demonstrate that the high-resolution capability is realized by steering nulls. The considerations will be useful for understanding the high-resolution techniques in the signal processing antennas. We then describe a modified version of MUSIC (Root MUSIC). We show the performance and robustness of the method. Furthermore, we introduce radar target identification and two-dimensional radar target imaging. These study fields are new applications of the signal processing antennas, to which a great deal of attention has been devoted recently.

Existing solid models often contain redundant primitives and null blocks, which both slows down the rendering process and makes the process complex. There has been recent progress toward solving this problem, but existing modeling schemes cannot support eliminating all the redundancies, especially the null blocks, from the solid models. This paper proposed a technique that can eliminate redundancies. By dividing a primitive into some surface dispersed points, a new primitive representation is obtained. The sample segments of the primitive or the object are used to locate composition position to prevent the null primitives from being generated. By drawing out the geometric shape points set corresponding to a common acting area, the volume boundary of a primitive or an object is evaluated by only the Boolean set operations. The null blocks can be picked out in terms of the volume boundary. The resulting solid model generated in this way has no redundancies and is suitable for fast rendering of the image.