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Wang L.,Nanyang Technological University | Bi G.,Nanyang Technological University | Wan C.,DSO National Laboratory | Lv X.,Nanyang Technological University
Signal Processing | Year: 2011

The block orthogonal greedy algorithm (BOGA) has been proven to successfully recover block-sparse signals in noiseless environments and the associated stability problem dealing with noisy signals has also been studied in the literature. This paper demonstrates that the recovery conditions of the BOGA previously reported can be relaxed by using a different definition of the block-coherence. The presented results in this paper provide a generalization of those reported by Tseng for block-sparse signal and serve as a complement of the BOGA reported by Eldar for noisy signals. © 2011 Elsevier B.V. All rights reserved. Source

Wang L.,Nanyang Technological University | Wan C.,DSO National Laboratory | Li S.,Shanghai JiaoTong University | Bi G.,Nanyang Technological University
Signal Processing | Year: 2015

Tonals generated by machineries with rotating elements typically have a harmonic structure with unknown fundamental frequencies, amplitude, harmonic order and phase. Detecting this type of signals is of great importance to numerous engineering applications. In the frequency domain, tonals are represented by a few harmonic frequencies, which appear in blocks, related to one or more fundamental frequencies. This block-sparsity property of the frequency content suggests alternative ways to recover and detect tonals by using sparse signal processing techniques. Motivated by the success of the block orthonormal greedy algorithm (BOGA), new detection architectures, which require no prior information about the number of the fundamental frequencies, are proposed for robust tonal detection in low signal to noise ratio (SNR) environments. The distributions of the test statistics of detection architectures are firstly analyzed theoretically and comprehensively based on the theory of order statistics. Detection performances are also analyzed and compared theoretically and experimentally. Significant improvements on detection performance in low SNR environments are shown over the conventional detectors that do not consider the harmonic structure and the sparsity of the tonals. © 2014 Elsevier B.V. Source

Wang L.,Nanyang Technological University | Bi G.,Nanyang Technological University | Wang C.,DSO National Laboratory
IEEE Region 10 Annual International Conference, Proceedings/TENCON | Year: 2012

This paper presents detectors for signal with harmonics to fully explore the inherent harmonic structure of the signal with unknown fundamental frequency, amplitude and phase in complex white Gaussian noise. For signals with harmonic characteristics, a transformed power spectrum is proposed to find the energy integration of all the harmonic components. We analyze the statistical property of the transformed power spectrum and develop a harmonic tonal detector by using the method of generalized likelihood hypothesis test. Another detector which considers equal contributions of data sequences is also developed and analyzed theoretically. Both detectors fully utilize the harmonic information of the signal. Simulation results show their improvements on the detection performance. © 2012 IEEE. Source

Cheng Y.,Nanyang Technological University | Luo X.,Agency for Science, Technology and Research Singapore | Song J.,Agency for Science, Technology and Research Singapore | Tsung-Yang L.,Agency for Science, Technology and Research Singapore | And 5 more authors.
CLEO: Science and Innovations, CLEO-SI 2015 | Year: 2015

We demonstrate 30 GHz mode-locked quantum well lasers on silicon using continuouswave optical injection, which emit at the L-band wavelength with integrated root-mean-square time jitter of 1.0 ps and radio-frequency-linewidth of 150 kHz. © OSA 2015. Source

Yao J.,Institute for Infocomm Research | Lee C.,DSO National Laboratory | Yeo S.P.,National University of Singapore
IEEE Transactions on Microwave Theory and Techniques | Year: 2011

The branch-line coupler may be redesigned for crossover application. The bandwidth of such a coupler can be extended by suitably incorporating additional sections into the composite design. Laboratory tests on microstrip prototypes have shown the return loss and isolation of the three- and four-section couplers to be better than 20 dB over bandwidths of 22% and 33%, respectively. The insertion losses and group delays vary by less than ±dB and ±1, respectively, for both prototypes. © 2010 IEEE. Source

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