Baha A. Obeidat

Spatial polarimetric time-frequency distributions for direction-of-arrival estimations

Time-frequency distributions (TFDs) are traditionally applied to a single antenna receiver with a single polarization. Recently, spatial time-frequency distributions (STFDs) have been developed for receivers with multiple single-polarized antennas and successfully applied for direction-of-arrival (DOA) estimation of nonstationary signals. In this paper, we consider dual-polarized antenna arrays and extend the STFD to utilize the source polarization properties. The spatial polarimetric time-frequency distributions (SPTFDs) are introduced as a platform for processing polarized nonstationary signals, which are received by an array of dual-polarized double-feed antennas. This paper deals with narrow-band far-field point sources that lie in the plane of the receiver array. The source signals are decomposed into two orthogonal polarization components, such as vertical and horizontal. The ability to incorporate signal polarization empowers the STFDs with an additional degree of freedom, leading to improved signal and noise subspace estimates for direction finding. The polarimetric time-frequency MUSIC (PTF-MUSIC) method for DOA estimation based on the SPTFD platform is developed and shown to outperform the time-frequency, polarimetric, and conventional MUSIC techniques, when applied separately.

Range and DOA estimation of polarized near-field signals using fourth-order statistics

An enhanced technique for estimating the range and direction-of-arrival (DOA) of narrowband near-field sources is presented. This technique utilizes fourth-order cumulants of the received signal across an array of two orthogonally polarized sensors. It is shown that the incorporation of the source polarization in an ESPRIT-based angle and range estimation technique provides improved performance over the case where the polarization information is absent in the problem formulation.

Polarimetric time-frequency ESPRIT

An ESPRIT (estimation of signal parameters via rotational invariance techniques) like algorithm for estimating the direction-of-arrival (DOA) of nonstationary polarized signals is developed. This algorithm relies on the recently introduced spatial polarimetric time-frequency distributions (SPTFD) as a platform to provide low computational, high resolution direction finding. The use of dual polarizations empowers the SPTFD with additional degrees-of-freedom, and improves the robustness of both the signal and noise subspaces. This improvement serves to enhance the DOA estimation, signal recovery, and source separation. In this paper the SPTFD are applied to the ESPRIT algorithm for improved angle-of-arrival estimation. Simulation results are provided which demonstrate the polarimetric time-frequency (PTF) ESPRIT resolution enhancement over the conventional ESPRIT, polarized ESPRIT, and time-frequency ESPRIT.

Spatial polarimetric time-frequency distributions and applications to direction-of-arrival estimation

Time-frequency distributions (TFDs) have evolved to be a powerful technique for nonstationary signal analysis and synthesis. With the use of a multi-sensor array, spatial time-frequency distributions (STFDs) have been developed and successfully applied to high-resolution direction-of-arrival (DOA) estimation and blind recovery of the source waveforms. In this paper, the polarimetric dimension is introduced to the STFDs resulting in the spatial polarimetric time-frequency distributions (SPTFDs) as a platform for the processing of non-stationary polarized signals. In the SPTFD platform, polarized signals are decomposed (projected) into two orthogonal polarization components, such as horizontal and vertical, and later processed in a manner where their polarization characteristics are exploited. This empowers the STFDs with additional degrees of freedom and improves the robustness of the signal and noise subspaces, and therefore, serving to enhance DOA estimation, signal recovery, and source separation performance. To demonstrate the advantages of the SPTFDs, the polarimetric time-frequency MUSIC (PTF-MUSIC) method for DOA estimation is proposed based on the SPTFD platform and is shown to outperform the time-frequency, polarimetric, and conventional MUSIC methods.

Polarimetric Array Processing for Nonstationary Signals

Time-frequency distributions (TFDs) have evolved to be a powerful technique for nonstationary signal analysis and synthesis. With the use of a multi-sensor array, spatial time-frequency distributions (STFDs) have been developed and successfully applied to high-resolution direction-of-arrival (DOA) estimations and blind recovery of the source waveforms. In this paper, we introduce the spatial polarimetric time-frequency distribution (SPTFD) as a platform to process nonstationary array signals with two orthogonal polar-ization components, such as horizontal and vertical. The use of dual polarization empowers the STFDs with additional degrees-of-freedom (D0Fs) and improves the robustness of the signal and noise subspaces. This improvement serves to enhance DOA estimation and signal recovery. To demonstrate the ef-fectiveness of the SPTFD platform, the polarimetric timefrequency ESPRIT (PTF-ESPRIT) method is proposed and is shown to outperform time-fre-quency, polarimetric, and conventional ESPRIT methods.

Direction finding using spatial polarimetric time-frequency distributions

In this paper, we introduce the spatial polarimetric time-frequency distribution (SPTFD) as a platform to process nonstationary array signals with two orthogonal polarization components, such as horizontal and vertical. The use of dual polarization empowers the STFDs and improves the robustness of the respective signal and noise subspaces. With the additional polarimetric information, improved direction finding performance can be achieved. To demonstrate such advantages, the polarimetric time-frequency MUSIC (PTF-MUSIC) method is proposed based on the SPTFD platform and is shown to outperform the MUSIC techniques based on the time-frequency, polarimetric, and conventional methods.

Nonstationary array processing for tracking moving targets with time-varying polarizations

This paper presents an approach for tracking nonstationary moving sources with both time-varying directions-of-arrival (DOA) and time-varying polarization signatures. The proposed approach is based on the spatial polarimetric time-frequency distributions (SPTFD). Unlike the conventional correlation matrix based approaches that sacrifice the source signal polarization properties and are not properly structured to utilize polarization diversity, the proposed approach uses the signal instantaneous polarization and instantaneous frequency information for improved target tracking and polarization estimation.

Performance analysis of DOA estimation using dual-polarized antenna arrays

Single- and dual-polarized arrays are used for direction-of-arrival estimation. It has been shown that adding polarization capability to an existing array allows reduction in the source correlation beyond that achieved by only doubling the number of antennas, especially when the sources are closely spaced. Recent work has shown that the joint spatio-polarimetric correlation is an effective measure of the performance dual-polarized arrays. In this paper, we analyze the variance of direction-of-arrival (DOA) estimation of the dual-polarized array. It is pointed out that the performance of dual-polarized arrays is related to both spatial and polarimetric correlation coefficients whereas the performance of single-polarized arrays is only a function of the spatial correlation

DOA and polarization estimation for wideband sources

This paper presents an approach for direction-of-arrival (DOA) and polarization estimations of far-field wideband signals using an array of cross-polarized dual-feed sensors. The wideband signals are decomposed into a set of narrowband signals. The coherent signal subspace processing technique is then applied to dimensionally extended source signal correlation matrices to construct a signal subspace. The utilization of polarization diversity through the use of a dual-feed cross-polarized array to process the polarized source signals lends an additional degree of freedom, leading to performance improvement over the case where only a single-polarization array is used.

Sensor configuration in polarized antenna arrays

Single- and dual-polarized array configurations are often used in imaging and radar applications. In this paper, spatio-polarimetric correlation are used as a framework to evaluate the direction finding performance of dierent receiver configurations employing double-feed dual-polarized array as well as arrays of single-feed single-polarized elements. The spatio-polarimetric correlation coecients are derived for several array reconfigurations and used to provide a configuration-based performance comparison based on spatial resolution and grating lobes.