The delay-and-sum (DAS) algorithm is widely used for beamforming in linear array photoacoustic (PA) imaging systems and characterized by fast execution. However, these algorithms suffer from various drawbacks, such as low resolution, contrast, high sidelobe artifacts, lack of visual coherence. More recently, adaptive weighting was introduced to improve the reconstruction image quality. Unfortun...

Channel capacities and data rates of mobile communications have been increasing to meet demands of modern communications. In order to achieve a low bit error rate (BER), we need high signal to interference plus noise ratio (SINR). To realize the high SINR, it is effective to use an adaptive array antenna [1]. The adaptive array antenna can reduce the influence of multipath rays. On the other ha...

During maneuvering, towed array beamforming degrades if a straight array is assumed. This is especially true for high-resolution adaptive beamforming. It is experimentally demonstrated that adaptive beamforming is feasible on a turning array, provided that array shape is estimated. The array shape can be inferred solely from the coordinates of the tow vessel’s Global Positioning System (GPS) wi...

in some mobile systems, intelligent antennas are used to increase efficiency in a wide frequency band and different environmental and electromagnetic conditions. environmental factors, such as position of nearby objects, antenna mobility and even user type, can vary the antenna input impedance appreciably. therefore, it is necessary to incorporate an adaptive impedance matching circuit between ...

This paper proposes an improved adaptive approach involving Bacterial Foraging Algorithm (BFA) to optimize both the amplitude and phase of the weights of a linear array of antennas for maximum array factor at any desired direction and nulls in specific directions. The Bacteria Foraging Algorithm is made adaptive using principle of adaptive delta modulation. To show the improvement in making the...

Modern wireless communications systems require improvement in capacity and data transmission speed. Adaptive array antennas separate spatially a desired wave from interference waves by controlling their radiation or beam pattern directivity. A digital beamforming (DBF) array performs adaptive beamforming by digital signal processing. However, the circuit scale, number of RF channels and power c...

A novel robust adaptive beamforming method for conformal array is proposed. By using interpolation technique, the cylindrical conformal array with directional antenna elements is transformed to a virtual uniform linear array with omni-directional elements. This method can compensate the amplitude and mutual coupling errors as well as desired signal point errors of the conformal array efficientl...

A/M~Tw!,In this paper, a multicarrier DS/CDMA system with adaptive antenna array is proposed for a multipath fading channel. A multipath fading channel is modeled as a Nakagami-m fading channel. The performance is evaluated in terms of bit error probability, and system capacity for the multicarrier DS/CDM A system with adaptive antenna array is estimated. From the analytic and simulation result...

We consider the bit-probe complexity of the set membership problem, where a set S of size at most n from a universe of size m is to be represented as a short bit vector in order to answer membership queries of the form “Is x in S?” by adaptively probing the bit vector at t places. Let s(m,n, t) be the minimum number of bits of storage needed for such a scheme. Several recent works investigate s...

This paper proposes a two-channel adaptive microphone array with target tracking to reduce external noise in hands-free speech communications. The proposed microphone array has two processings, one of which is beamforming and the other is target tracking. The Frequency Domain Generalized Sidelobe Canceller (FDGSC), which is the frequency domain adaptive filter derived from the time domain adapt...