Hongya Ge

• Doctor of Philosophy
• New Jersey Institute of Technology

In this Letter, the authors present a closed‐form derivation of the probability density function (PDF) for the notch depth (ND) of the dominant mode rejection adaptive beamformer (ABF). Their PDF expression closely approximates the true PDF for the case of single interferer at reasonable levels of interference‐to‐noise ratio. Their simulation resul...

The detection and localization of signals using large arrays is challenging in low coherenceunderwater environments. Poor spatial coherence is a consequence of signal wave front distortions caused by time-dependent three-dimensional spatial fluctuations in the sound speed from internal waves, fronts, and random medium effects such as turbulence. In...

In this work, a two-stage multi-rank solution for passive ranging is presented for acoustic sensing systems using multi-module towed hydrophone arrays operating in underwater environments subject to spatialcoherence loss. The first stage of processing consists of adaptive beam-forming on the individual modular array level to improve the signal-to-n...

This work presents some new results on the structures of, and our interpretation on, the multi-rank filters used for passive wavefront curvature (WFC) ranging. Such a WFC ranging systems uses a large-scale distributed arrays with many spatially separated modular arrays, operating under environments subject to a spatial coherence loss. Working on th...

This work presents our data analysis results on modeling spatial coherence in a distributed passive array ranging system consisting of three volumetric module arrays. We show that a simple analytical approximation that was previously derived for modeling signal spatial coherence losses in wireless system which represented the random medium effects...

In this work, the problem of multichannel cross-spectrum density (MCSD) estimation is studied. Based on a multichannel data model, the classic periodogram based MCSD estimator and the minimum variance (MV) based MCSD estimator are tested for cross-spectrum density estimation. Our major contribution in this work is a canonical correlation analysis (...

In this work, we present some asymptotic results on the maximum likelihood multi-rank processor for passive wavefront curvature ranging systems using large-scale distributed arrays. We assume that the operation environment for the distributed arrays is subject to a spatial coherence loss. Under an exponential coherence model, analytical expressions...

In this work, we study the eigen-structure of the data covariance matrix in an asynchronous CDMA system. Our results reveal the joint effect of spreading codes and power control on warp converging Wiener filters. We further provide suggestions on spreading code selection and power control strategy in CDMA system design, where stable and predictable...

In this work we derive the maximum likelihood estimator for passive wavefront curvature ranging systems operating in environments subject to a spatial coherence loss. As a consequence of the spatial coherence loss, the optimum processor is no longer a rank-1 matched filter and now instead involves a multi-rank weighted combination of the data based...

This work presents our analysis on adaptive beamforming and combining techniques applied to a system consisting of distributed antenna arrays. Our analysis reveals the connection between the theoretical and the practical schemes for data combination. The important roles played by the canonical correlations (CC), which may or may not exist among mul...

In array signal processing, the performance of parameter estimation is effected by the unknown nonuniform perturbations on the sensors of receiver array. In this work, the problem of passive localization of near-field sources with partly calibrated subarray-based array is studied. Rank reduction (RARE) is extended to its 2-Dimensional version to so...

In this paper, we present a study of hemoglobin-hemoglobin interaction with model reduction methods. We begin with a simple spring-mass system with given parameters (mass and stiffness). With this known system, we compare the mode superposition method with Singular Value Decomposition (SVD) based Principal Component Analysis (PCA). Through PCA we a...

This work presents our research results on the capability of passive source localization using a towed multi-module array in underwater acoustic environments. We developed new Cramer-Rao Lower Bound (CRLB) results for assessing the array's source localization capability under environmental uncertainties, such as array modules' positions and acousti...

This work provides a canonical coordinates perspective for direction-of-arrival (DOA) estimation using two distributed sensor arrays. A new method for estimating the DOA of multiple far-field narrow-band sources is proposed. Distinct from existing asymptotic results for canonical correlation analysis (CCA) in such an application, our special intere...

Sickle cell anemia is the first disease whose genetic cause was pinpointed at the DNA level. Sickle cell disease is caused by the switch of a single DNA base pair in the hemoglobin gene from A to T, which in turn changes an amino acid in the hemoglobin protein from glutamic acid to valine. Normal hemoglobin at this location is slightly hydrophilic...

This work proposes a method for localizing a single near-field source using a moving array. Using a phase correction factor calculated from two sequences of selected data snapshots, we extend the array aperture and compute the initial estimates of the source's bearing and range from the extended data sets. With the initial estimates of bearing and...

This work presents an effective algorithm for radio frequency interference (RFI) identification using dynamic power spectrum statistics in the frequency domain. Statistical signal processing techniques such as hypothesis testing and variance analysis are utilized to derive a test statistic for effective and efficient RFI identification. Starting fr...

This work provides analytical results on the canonical correlation analysis (CCA) of data sets from two spatially separated arrays of sensors. Our case studies cover both single source and multiple source signals in either white or colored noise fields for array signal processing. We derive analytical expressions of the canonical correlation for th...

This work studies the effect of in-phase/quadrature (I/Q) imbalance on time-reversal space-time block coded (TR-STBC) communication systems operating over frequency-selective fading channels. The transceiver I/Q imbalance in a 2 times 1 TR orthogonal STBC (TR-OSTBC) system is studied in detail, and low-complexity mitigation solutions are proposed b...

In this work, a grouped linear constellation precoded orthogonal frequency-division multiplexing (GLCP OFDM) system, with the transceiver in-phase/quadrature (I/Q) imbalance operating over frequency-selective fading channels are studied. A new subcarrier grouping scheme in such a system is proposed. Through analysis and simulations, we demonstrate...

In this work we study the performance degradation caused by the in-phase/quadrature (I/Q) imbalance of the transceivers in multiple-input multiple-output (MIMO) space-time block coded (STBC) communication systems. The 2-Tx orthogonal STBC (OSTBC) systems, 4-Tx quasi-orthogonal STBC (QOSTBC) systems, and 4-Tx rotated QOSTBC (RQOSTBC) systems in the...

In this work, the encoding/decoding scheme for the cyclic prefix (CP) based time-reversal quasi-orthogonal space-time block coded (TR-QOSTBC) wireless communication systems over frequency-selective fading channels is studied. A CP based 4 times 1 TR-QOSTBC system is studied in detail, and the upper bound of the pairwise error probability (PEP) is d...

Maximum a posterior (MAP) estimator has been shown to perform perfectly for direction-of-arrival (DOA) under the assumption that the number of sources is known. Specifically, in this work we proposed a MAP estimator for DOA, and extend it to a new approach called DDBM for joint detection and DOA estimation simultaneously. Results of both simulation...

Sickle cell anemia is the first disease whose genetic cause was pinpointed at the DNA level [7]. Sickle cell disease is caused by the switch of a single DNA base pair in the hemoglobin gene from A to T, which in turn changes an amino acid in the hemoglobin protein from glutamic acid to valine. Normal hemoglobin at this location is slightly hydrophi...

Using the Cramer-Rao bound (CRB) as an indicator of potential performance, in this work we study a moving array's ability to estimate parameters of a narrow-band signal. Specifically, the hybrid CRB on source frequency and bearing are studied for signals containing both random fading parameters and unknown deterministic ones. The derived hybrid CRB...

This work develops an iterative solution to maximum likelihood estimation of source parameters in unknown but partially correlated non-uniform noise field when a moving array is used for data collection. With the proposed solution, the temporal frequencies and the direction of arrivals (DoAs) of source signals can be obtained effectively. Computer...

The paper introduces and provides a simple proof of an interesting matrix inversion identity involving subspaces. Using this identity, new insights and interpretations are provided about beam space-based adaptive beamformers and the generalized sidelobe canceller. In addition, system performance measures and losses in terms of the achievable SINR a...

It has been shown in our previous work [1][2] that for signal modes with a specially structured data covariance matrix, a warp (stable and predictable early) convergence can be achieved using the reduced-rank conjugate gradient (RRCG) Wiener filter (WF) for multiuser detection (MUD) in code division multiple access (CDMA) communication systems. In...

In this work we study the performance degradation caused by the in-phase/quadrature (I/Q) imbalance in space-time block coded (STBC) multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) communication systems. The 2-Tx Alamouti scheme, 4-Tx quasi- orthogonal STBC (QOSTBC) scheme, and 4-Tx rotated QOSTBC (RQOSTBC) s...

In this paper, a radio frequency interference (RFI) excision algorithm using variance-based analysis on power spectral statistics is proposed and tested on the solar data collected from our frequency agile solar radio-telescope (FASR) subsystem test-bed (FST). A threshold approach working on a proposed test statistic tau(x; f ), shown to be F-distr...

This paper considers the development of adaptive beamforming algorithms for a prototype volumetric array. Volumetric arrays are desirable in passive sonar systems because of their ability to resolve left-right ambiguity. However, adaptively beamforming volumetric arrays poses several unique challenges compared to linear arrays such as the large num...

In this work, a parametric method is proposed to estimate the Doppler spread, or the mobile speed by modeling the received data as an autoregressive process. The method can be extended to a spatial-temporal parametric Doppler spread estimator when multiple antennas are available at the receiver. Compared to the nonparametric estimator based on peri...

Driven by the need for identifying the presence of flow noise components in a towed volumetric acoustic array, methodologies are developed for high resolution 3-dimensional (3-D) wavenumber-frequency (k-f) analysis based on Krylov space techniques. These methods are applied to actual noise data from a sea trial. The experimental results indicate th...

The Cramer-Rao lower bound (CRLB) is derived for the channel estimation of direct sequence-code division multiple access ultra-wideband (DS-CDMA UWB) communication system. We have modified the channel model and reduced the number of estimation parameters. Furthermore, a low-complexity data-aided Least Square (LS) channel estimation algorithm is pro...

We propose a novel precoded UWB (PUWB) system designed for multiple access (MA) communications. In our design, we try to enable concentration of the received signal power from different users (synchronized) at different time slots, thus make the matched filter (MF) based multiuser detection eligible for optimal reception. The optimum code is constr...

This work studies the performance of a data-driven reduced rank scheme for rapid timing acquisition in multiple access communications. Our results show that when only a limited amount of preamble bits are available, instead of the true second-order statistics (SOS), the reduced rank scheme provides reliable timing information. Exploiting the struct...

The performance of Krylov subspace-based dimensionality reduction for adaptive beamforming is analyzed using a simple second-order Taylor series approximation to the mean output signal-to-noise ratio (SNR). It is shown that the predicted SNRs accurately follow the experimentally measured SNR and explain the threshold effects when the angles or spac...

In this work, we present a class of low-complexity reduced-dimension adaptive beamformers constructed from expanding Krylov subspaces. We demonstrate how the data dimensionality reduction obtained from Krylov pre-processing decreases the sensitivity of reduced-rank adaptive beamforming techniques to incorrect model-order selection and lessens the c...

In this work, we, using a mapping, transform the mismatch compensation problem into an estimation and equalization problem. By doing so, the in-phase and quadrature (I/Q) system mismatch parameters, i.e., the amplitude gains of I/Q channels and the phase imbalance, can be first estimated reliably and then mitigated by equalization. We also derive t...

This work studies the impact of the network resource constraints on the performance of wireless sensor multi-hop relay networks. A differential space-time coding and the cooperative relay scheme for cross layer design is introduced in multi-hop wireless sensor networks. To analyze the network performance of such a system, the relay system from sour...

In this work, a channel estimation scheme is introduced to single carrier block transmission systems. Compared to the conventional method, the proposed scheme has similar estimation accuracy but with higher transmission efficiency and lower complexity. Under the anti-polar constellation constraint, the optimal training sequence design is studied. F...

This work studies the application of differential space time block code (STBC) for wireless multi-hop sensor networks in fading channel. We select multiple sensors as parallel relay nodes to receive and transmit signals from the previous hop. These relay nodes do not exchange symbols with each other but forward the symbols in parallel to the destin...

This work presents our new results on data-driven rank reduction for rapid timing acquisition in multiple access (MA) communications systems. The results generally apply to multiple access systems, such as code-division multiple access (CDMA) and the ultra-wide band (UWB) systems, operating over environments with severe radio interference. Our resu...

Summary form only given. Direct-sequence spread-spectrum (DS/SS) communication systems have certain degree of inherent immunity to intentional and/or unintentional jammers. However, in some applications, the jammer might be much stronger than the desired DS/SS signal, and the processing gain due to spreading might be insufficient to provide enough...

Realizing the large user capacity planned for ultra-wideband (UWB) systems motivates multiuser detection (MUD). However, it is impractical to implement conventional chip-rate MUD methods, because UWB signaling gives rise to high detection complexity and difficulty in capturing energy scattered by dense multipath. In this paper, we develop a recepti...

In this work, the idea of cross-layer design for wireless sensor networks is exploited to improve the network performance. We present a new energy efficient cooperative routing scheme with space diversity using space-time block codes (STBCs) as well as the link quality. In our solution, the selected multiple nodes act as multiple transmitting and r...

In this work, we present interesting case studies that lead to new and deeper results on fast convergence of reduced-rank conjugate gradient (RRCG) Wiener filters (WF), for applications in communications and sensor array signal processing. We discover that for signal modes with a specially structured Gram matrix, which induces L groups of distinct...

Using the notion of expanding subspace and the framework of reduced-rank signal processing, we present our latest discovery on applying the vector and matrix conjugate gradient (CG) methods to design reduced-rank linear MMSE multiuser detectors (MUD) for code division multiple access (CDMA) systems. We show that for a synchronous CDMA system with K...

We propose a new block time-reversal conjugate based quasi-orthogonal space-time block encoding and decoding (QO-STBC) scheme for a wireless system with four transmit antennas in frequency selective fading channels. The proposed scheme effectively combats channel dispersion and frequency selectivity due to multipath, yet still provides full diversi...

In this work, we present a new space-time orthogonal coding scheme with full-rate and full-diversity. The proposed space-time coding scheme can be used on quaternary phase-shift keyed (QPSK) transceiver systems with four transmit antennas and any number of receivers. An additional feature is that the coded signals transmitted through all four trans...

In this paper, we present a new fast maximum likelihood (ML) detection algorithm for quasi-orthogonal space-time block codes ( QO-STBC). Observed in a transformed signal space, the QO-STBC encoder embeds information into a group of orthogonal subspaces of rank two. We propose a fast technique that separates information embedded in each rank-two sub...

In this paper, we propose a new technique to effectively suppress nonstationary jammer in DS/SS communication systems. This technique combines a new scheme of instantaneous frequency (IF) estimation with the projection based interference suppression. In order to capture jammer subspace a time-varying autoregressive (TV-AR) modeling is used to estim...

Proposed and studied in this work is a reduced complexity maximum likelihood (ML) detection scheme, which uses a predecoder guided local exhaustive search, for V-BLAST systems. A polygon searching algorithm and an ordered successive interference cancellation (O-SIC) sphere searching algorithm are major components of the proposed multistep ML detect...

This work proposed the linear minimum mean square error (LMMSE) space-time receivers for synchronous multi-rate direct sequence code devision multiple access (DS/CDMA) systems. The performance of the proposed receivers is analyzed. The high-rate (HR) LMMSE space-time receiver with combining technique can provide essentially the same performance for...

We present a novel space-time orthogonal coding scheme with full-rate and full-diversity on a QPSK constellation for communication systems with four transmit antennas. We also study the performance of the newly proposed coding scheme in comparison with that of half rate full diversity orthogonal codes as well as full rate half diversity quasi-ortho...

In this work, group-wise successive interference cancellation (GSIC) scheme for multi-rate CDMA systems is proposed. A multi-rate CDMA system is a CDMA system that can support voice users together with data users which may have different data rates. In the proposed group-wise detection, users with the same information rate are grouped and detected...

We first develop a reduced-rank minimum mean squared error (MMSE) detector for direct-sequence (DS) code division multiple access (CDMA) by forcing the linear MMSE detector to lie in a signal subspace of a reduced dimension. While a reduced-rank MMSE detector has lower complexity, it cannot outperform the full-rank MMSE detector. We then concentrat...

We first develop a reduced-rank minimum mean squared error (MMSE) detector for direct-sequence (DS) code division multiple access (CDMA) by forcing the linear MMSE detector to lie in a signal subspace of a reduced dimension. While a reduced-rank MMSE detector has lower complexity, it cannot outperform the full-rank MMSE detector. We then concentrat...

In this paper, we present a systematic method for multiple symbol detection of differentially encoded MPSK signals of a wireless system with two transmit antennas and multiple receivers. Compared to the existing pair-symbol detection method [7] and four-symbol detection symbol detection method [9], respectively, the proposed method keeps such advan...

In this work, we present a new space-time differentially coded transceiver system for DS-CDMA applications. The proposed solution allows us to embed transmit diversity into the space-time-frequency (STF) domain in a simple yet effective way. It also enables a simple scheme for differential detection and data separation at the receiver without chann...

An approximate maximum likelihood method for joint estimation of time delays and directions-of-arrival for direct-sequence code-division multiple-access systems over multipath Rayleigh fading channels is presented. To reduce the computational complexity, the multi-dimensional maximisation problem is transformed into two simple one-dimensional maxim...

We develop an approximate maximum likelihood (ML) method for joint estimation of time delays and directions-of-arrivals (DOA) for direct-sequence code-division multiple-access (DS-CDMA) systems over multipath Rayleigh fading channels. In developing the proposed estimation scheme, we model the known training sequence of the desired user as the desir...

An approximate maximum likelihood (ML) method for joint estimation of time delays and directions-of-arrivals (DOAs) for the direct-sequence code-division multiple-access (DS-CDMA) systems over the multipath Rayleigh fading channels is developed. The proposed estimation scheme is developed by modeling the known training sequence of the desired user...

This paper presents a new differential encoding scheme for direct sequence code division multiple access (DS-CDMA) systems using space-time block code with space-time transmit diversity (STTD). The proposed generalized differential encoding scheme at the transmitter and the corresponding low complexity differential decoding scheme at the receiver e...

The performance of new differential detection schemes with transmit diversity (TD) for direct-sequence code division multiple access (DS-CDMA) systems is evaluated. Two TD schemes are considered. One is the orthogonal transmit diversity (OTD) and the other is the space-time transmit diversity (STTD). To enable blind detection, the two schemes of di...

We propose a centralized iterative time delay estimation scheme for asynchronous DS-CDMA communication systems. The proposed algorithm utilizes known training sequences and signatures for all multiple-access users to get the initial estimates of time delays. After that, the K-1 interfering signals are reconstructed with the estimated parameters and...

In this work, groupwise successive interference cancellation scheme for multirate CDMA signals is proposed. The proposed detector operation is based on the minimum mean square error (MMSE) criterion. It has the promise of decision feedback interference cancellation for superior performance compared to the linear MMSE detection at the cost of a mode...

The minimum variance receiver has been proposed to blindly suppress the multiple-access interference in CDMA channels by minimizing the receiver's output variance based on constrained optimization. We consider the reduced-rank minimum variance receiver in asynchronous CDMA channels. The reduced-rank detector uses a reduced-rank approximation of the...

The minimum variance receiver has been previously proposed to suppress the multiple-access interference (MAI) blindly in CDMA channels by minimizing the receiver's output variance based on constrained optimization. In this paper, we propose a low-complexity minimum variance receiver that achieves almost the same performance as the high-complexity o...

A new Kalman filter based space-time (S-T) receiver is proposed in this paper. By modeling an asynchronous CDMA system as a first-order state-space model, we can recursively obtain the finite-length linear minimum mean square error (LMMSE) receiver, which provides the best multiple access interference (MAI) cancellation among all the linear filters...

In this work, we present a new, computationally simple scheme (termed multi-shot approach) to separate and detect multiuser signals in an asynchronous code-division multiple-access (CDMA) communications system. By exploring the structure inherent in the matrix decomposition of properly arranged data, obtained from multi-shot matched filtering, we p...

We present a simple approach to estimate and correct the carrier offset in an orthogonal frequency division multiplexing (OFDM) system. The approach leads to a computationally and statistically efficient estimator for the carrier offset. Computer simulations verify that the estimation accuracy is comparable to the Cramer-Rao bound (CRB). We demonst...

This work provides various simplified Bayesian-based multiuser detectors, including both linear and non-linear detectors, for CDMA communications systems. Due to the non-Gaussian nature of the problem, the Bayesian solutions are generally non-linear. Under the linear constraint, the Bayesian solution leads to the linear MMSE (LMMSE) estimator based...

Linear space-time multiuser detectors are proposed for CDMA systems which support users transmitting at different bit rates. The performance of the LMMSE space-time dual-rate receiver is studied in the context of two multi-rate access methods: multi-code (MC) access where high data rate users multiplex information streams onto multiple codes, and v...

We present a simple and fast delay estimation approach to signal acquisition for direct-sequence CDMA communication systems. The main idea is to first intentionally map a lower-dimensional objective function into a higher-dimensional one by change of parameter variables. In doing so, we are able to view the objective function in a parameter space o...

The low-rank minimum mean-squared error (MMSE) detector for direct sequence (DS) spread-spectrum code-division multiple-access (CDMA) is proposed. The low-rank linear MMSE detector lies in a subspace of the signal space. We demonstrate that when the dimension of the signal space is lower than the processing gain and the MMSE detector is obtained us...

A LMMSE multi-rate detector for synchronous CDMA frequency selective Rayleigh fading channels is proposed. A comparative study between the conventional multi-rate RAKE receiver and suboptimal multi-rate detector is presented. The conventional multi-rate RAKE receiver is severely limited by the near-far effects in the multiuser environment. Both sub...

This work is an extension of the multi-rate LMMSE detectors (Ge 1997) for asynchronous multi-rate CDMA systems. The proposed LMMSE detectors can work on dual-rate mode according to different quality-of-service (QoS) requirements and computational constraints. In using the proposed multirate LMMSE detectors, only the signature and timing information...

We present an efficient method for estimating nonlinearly entered parameters of a linear signal model corrupted by additive noise. The method uses the Gram-Schmidt orthonormalization procedure in combination with a number of iterations to de-bias and re-balance the coupling between non-orthogonal signal components efficiently. Projection interpreta...

We extend the LMMSE multiuser detector to multi-rate CDMA systems, where different users have different quality-of-service (QoS) requirements. The proposed LMMSE detectors can work on dual-rate mode according to different computational constraints. Only the signature of the desired user is needed in using the proposed multi-rate LMMSE detectors. Th...

In this work, we proof the equivalence between various forms of LMMSE (linear minimum mean square error) estimate-based multiuser detectors for CDMA communications. An adaptive scheme of implementing the LMMSE multiuser detector is proposed. Simulation shows that the proposed detector not only approximates the exact solution with high accuracy and...

Presented in this article are analytical expressions of the performance measure on the LMMSE estimate-based multiuser detector, including an error probability expression and its computationally and notationally efficient approximations, signal to interference-plus-noise ratio, and asymptotic efficiency. Also included in are adaptive implementation...

Using Cramer-Rao lower bounds (CRLBs) for estimating time of arrival and frequency of a burst of sinusoid, we investigate the effect of the location and extent of the observation interval, relative to the support of the received signal pulse, and the effect of not knowing the time duration of the pulse. The effect of filtering the received waveform...

The use of dual polarized transmission provides a means of doubling the spectral efficiency in radio communications systems. Antenna imperfections and/or non ideal channel conditions introduce cross-polarization interference, degrading the performance. Additionally, the performance may be further degraded by the presence of a narrow-band interferer...

We analyze the performance of linear minimum mean squared error (LMMSE) estimate-based multiuser detector for CDMA communication systems. Remarkable consistency is achieved through numerical evaluation of our analytical results and computer simulations. We also compare the performance of the LMMSE detector and the adaptive bootstrap multiuser detec...

We analyze the performance of linear minimum mean squared error (LMMSE) estimate-based multiuser detector for CDMA communication systems. Through numerical evaluation and computer simulations, we also compare the performance of the LMMSE detector and the adaptive bootstrap multiuser detector. Our analysis and simulations show that even though these...

We present an novel method of fast and accurate estimation of the frequencies of sinusoids from short data records of wide-band under-sampled data. By introducing properly chosen delay lines, and by using sparse linear prediction, our proposed method provides unambiguous frequency estimates using low A/D conversion rates. It provides a new way to i...

Based on Bayesian philosophy, we propose a simplified detection scheme for multiuser separation in CDMA communication systems. The proposed detector uses a multi-stage approach to achieve improved detection performance. In the first stage, we use a marginal Bayesian estimate to get a tentative estimate of the random signal vector. In the second sta...

First Page of the Article

The authors extend previous work on ambiguity resolution in sparse linear prediction to array signal processing. A non-uniformly spaced linear array with minimum number of sensors is introduced in order to obtain high resolution spatial frequency estimates at reduced computation and at minimum hardware cost. By properly choosing inter-element spaci...

The authors extend previous work on ambiguity resolution in sparse linear prediction to array signal processing. A non-uniformly spaced linear array with minimum number of sensors is introduced in order to obtain high resolution spatial frequency estimates at reduced computation and at minimum hardware cost. By properly choosing inter-element spaci...

In this paper, we extend our previous sparse linear prediction (SLP) method for two-dimensional (2-D) applications. The temporal and spatial frequencies of multiple sinusoids are simultaneously estimated in pairs, rather than separately, from the outputs of a sparse linear array. Possible ambiguities due to the large interelement spacings can be re...

We present some results of our analysis of Kumaresan's (1982) sparse linear prediction method for estimation of frequencies of sinusoids. Refinements of Kumaresan's method are proposed for the case of two sinusoids which are not close in frequency. When the data is corrupted by additive white Gaussian noise, the probability of correctly resolving a...

A computationally efficient fast maximum-likelihood (FML) estimation scheme, which makes use of the shape of the surface of the compressed likelihood function (CLF), is proposed. The scheme uses only multiple one-dimensional searches oriented along appropriate ridges on the surface of the CLF. Simulations indicate that the performances of the propo...

The problem of estimating the frequencies of two sinusoids in white Gaussian noise using only the sequence of phase angles of the complex-valued data is addressed. The authors extend the single sinusoid results of Tretter (1985), Kay (1989), Lang and Musicus (1989), and Lovell et al. (1991) to two sinusoids. A computationally simple estimation sche...

We describe algorithms for real-time radio frequency interference (RFI) excision based on data from a prototype instrument for the Frequency Agile Solar Radiotelescope (FASR), called the FASR Subsystem Testbed (FST). The FST instrument records data over a 500 MHz bandwidth at full time resolution [1], allowing off-line application of various RFI ex...