Power Inversion Adaptive Array Research Articles

Impact of Element Pattern on the Performance of GNSS Power-Inversion Adaptive Arrays

Power-inversion (PI) adaptive arrays are widely used in Global Navigation Satellite System (GNSS) receivers for interference mitigation. The effects of element patterns on the performance of PI adaptive arrays are investigated in this paper. To this end, the performance of adaptive arrays is investigated by Monte Carlo simulations, using CST Microwave Studio (Dassault Systems, Vélizy-Villacoublay, France) to calculate the radiation patterns of circular microstrip elements which are used to compute the adaptive weight and the adaptive array gain. It is shown that the performance of PI adaptive arrays is mainly dependent on the gain pattern of the reference antenna element rather than the non-reference elements because the algorithm essentially pushes the elements into an unequal position. Furthermore, the results show that the impact of mutual coupling on the performance of the antenna array can be associated with the radiation patterns of the reference element, which is helpful in selecting the optimum reference element without increasing computational complexity, especially for small GNSS arrays.

Optimum reference element selection for GNSS power‐inversion adaptive arrays

An improved algorithm for power-inversion adaptive antenna arrays used in global navigation satellite systems (GNSS) receivers is proposed. Compared with traditional methods which select the reference element arbitrarily, the proposed method is capable of selecting the optimum reference element at signal acquisition stage. The criterion of the reference element selection is to maximise the acquisition test statistic results by developing the generalised likelihood ratio test detector. Monte Carlo simulation results show that the proposed method can improve the array performance significantly.

A New Method of LCMV Algorithm in GNSS Anti-Interference

Owing to the satellite signal strengths of GNSS is so low that it is interfered with powerful signal, that how to effectively resist interference is becoming a problem.In this paper,first LCMV algorithm based on the power-inversion adaptive array is deduced from theory in certain mathematical model ,what’s more ,for avoiding computing the inverse of matrix, LCMV algorithm is improved and then is verified through the Matlab-simulation .Last,the hardware design is given for the realization of this algorithm.

Research and Simulation of LCMV Algorithm in GNSS Anti-Interference

Owing to the satellite signal strengths of GNSS is so low that it is interfered with powerful signal, that how to effectively resist interference is becoming a problem.In this paper,first LCMV algorithm based on the power-inversion adaptive array is deduced from theory in certain mathematical model ,what’s more ,for avoiding computing the inverse of matrix, LCMV algorithm is improved and then is verified through the Matlab-simulation .Last,the hardware design is given for the realization of this algorithm.

An adaptive array antenna using blind extraction of signal subspace in radar

A problem in radar is the significant degradation in system performance when the power of jamming electromagnetic signals is larger than the desired signal. To address this problem, we herein propose a blind jamming signal suppression method using an array antenna. The proposed method determines the matrix that projects onto the space orthogonal to the signal subspace of the jamming signals from the eigenvectors of the correlation matrix of the received signal composed of the jamming signal component. Then the projection transform is applied to the received signal vector containing the desired signal. By using the eigenvector corresponding to the maximum eigenvalue of the correlation matrix of the output signal vector of the transform as the weighting coefficients, the signal-to-noise ratio (SNR) is improved by maximum ratio combining of the desired signal component. Based on a performance evaluation by computer simulation, the jamming signal suppression capability exhibits improvement compared to the power inversion adaptive array of the same blind processing. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 89(12): 45–53, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20303

A software antenna configuration having robustness for strong interference signal that arrives suddenly—Utilizing the power inversion characteristics in the second eigenvector beam output

AbstractAn environment is assumed in which a strong interference wave is suddenly incident. To produce an antenna robust to such an environment, a method is proposed in which an eigenvector beamspace adaptive array (EBAA) is formed by using the weight of the eigenvector for the first eigenvalue in the case of weak interference, but the weight of the eigenvector for the second eigenvalue in the case of strong interference. The performance of the interference suppression in the latter case (desired wave power ≪ interference wave power) is analyzed by numerical calculations and simulations. Also, this EBAA is superior in terms of configuration and performance to the well‐known power inversion adaptive array (PIAA). Based on the results, a software antenna configuration method for real‐time understanding of the propagation environment and adaptive switching of the algorithm is discussed. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(8): 20–28, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10099

Fast null steering algorithm for arbitrary two-dimensional power inversion arrays

In the paper, a fast source tracking algorithm for an arbitrary two-dimensional power inversion adaptive array is presented and investigated. By solving two sets of linear equations to calculate the preprocessing needed, the algorithm tracks the environment through adaptively adjusting the array response zeros directly in a time-multiplexed manner to minimise the output power. The main advantages of the algorithm are that it has good tracking behaviour and the zero or source positions are directly available.

Resolution of coherent sources in power inversion arrays with a fast zero tracking algorithm

A fast zero tracking algorithm for resolving coherent sources in power inversion adaptive arrays is investigated. To resolve M directional sources with a maximum coherent group size of Ma, the original M + 1 element power inversion array is augmented by Ma − 1 elements to result in a total of Ma identical but spatially shifted M + 1 element arrays. After performing some simple preprocessing, the M controlling zeros in these Ma arrays are adaptively updated in a time-multiplexed manner by using the LMS algorithm to minimise the spatially averaged output power to track the external environment. Since only one zero is adjusted at any instant, the new algorithm has almost the same implementation complexity as when the LMS algorithm is used directly. However, rather than having to use a root-finding routine, the directions of the sources can be obtained directly from the zeros being updated in the new algorithm. Also, with the same asymptotic time constant for all the zeros, the new algorithm can be much faster than the conventional LMS algorithm, especially under situations where the eigenvalue spread of the element covariance matrix is large.

Fast null-steering algorithm for broadband power inversion array

A fast algorithm for broadband power inversion adaptive arrays is investigated. Essentially, in this algorithm, each broadband jammer is individually tracked by steering a broadband null formed from the use of a set of tapped delay line filters in a Davies beamformer. To steer a particular broadband null to its optimal position, the algorithm first swaps the associated set of null-controlling filters into the last stage of the beam former, and then employs the LMS algorithm with a simple time-invariant decorrelation preprocessor to adjust the filter parameters to minimise the output power for a number of iterations. Performing this procedure for each null in turn results in continuous tracking of all the broadband jammers in a cyclical manner. Although the algorithm requires implementation of the broadband tapped delay-line Davies beamformer, only one tapped delay-line filter is being adaptively updated at any instant. Thus, when the number of elements is small, the overall implementation complexity of the proposed algorithm is comparable to that of using the LMS algorithm directly. However, since each broadband null is independently steered, the proposed algorithm has a much faster convergence behaviour, particularly under situations of severe jamming.

Broadband power inversion adaptive array

AbstractThe power inversion adaptive array proposed by Compton differs from other adaptive arrays in that it does not require any information on the desired signal. However, there is a sudden reduction in the ratio of signal to interference and noise (SINR) at the output terminal when the relative bandwidth of the interference signal exceeds 5%. In this paper the elements are arranged in a circular arc and a formula is proposed for microprocessor determination of the element weight from the covariance between the element inputs. It is shown that the decrease in SINR is kept below 3 dB even when the relative bandwidth of the interference is as large as 50%. In Method 1 of the circular arc arrangement an element is placed at the center of the circle and in Type 2 no element is placed at the center. Wideband elimination of the interference can be achieved with the arrival angle orthogonal to the line connecting two arbitrary elements. The element arrangements are studied with a low level of redundancy for this ideal angle of arrival. It is shown that a system without redundancy can be realized with a 4‐element array of Method 2.

Upper Bound of a Loop Gain in a Power Inversion Adaptive Array

A loop gain is an important parameter in a power inversion adaptive array. The upper bound value of the loop gain is obtained which prevents the array suppressing a desired signal seriously. This result is very useful for determining the loop gain.

Adaptive Power Inversion Antenna Arrays

In the past, theoretical and experimental investigations on adaptive antenna arrays have mostly been based on algorithms employing the gradient techniques. These techniques call for highly-stable multiple feedback loops with low noise performance. However, a new approach to solving adaptive antenna problems which employs the pseudogradient approximation techniques, wherein a direct computation of the gradient is not required, may sometimes be more useful. Presented in this paper are application of two types of the pseudogradient algorithms, namely, the random search with paired trials and the stochastic-m-gradient, to power inversion adaptive antenna arrays. These arrays achieve inversion of the power ratio of the desired signal and the interference signal without a detailed knowledge.of the desired signal structure and the arrival angle. The method is illustrated by a computer simulation.

The Power-Inversion Adaptive Array: Concept and Performance

The use of a power-inversion adaptive array to improve the signal-to-interference ratio in a communication system is described. "Power inversion" refers to the ability of an adaptive array to invert the power ratio of two received signals. The power-inversion ion technique is useful because it does not require detailed ledgeknow about desired-signal structure or arrival angle. The perform ance attainable with a power-inversion array is described and typical al design curves are presented.