2017/1

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Novel Design of Recursive Differentiator Based on Lattice Wave Digital Filter
(Společnost pro radioelektronické inženýrství, 2017-04) Barsainya, Richa; Rawat, Tarun K.
In this paper, a novel design of third and fifth order differentiator based on lattice wave digital filter (LWDF), established on optimizing L_1-error approximation function using cuckoo search algorithm (CSA) is proposed. We present a novel realization of minimum multiplier differentiator using LWD structure leading to requirement of optimizing only N coefficients for Nth order differentiator. The gamma coefficients of lattice wave digital differentiator (LWDD) are computed by minimizing the L_1-norm fitness function leading to a flat response. The superiority of the proposed LWDD is evident by comparing it with other differentiators mentioned in the literature. The magnitude response of the designed LWDD is found to be of high accuracy with flat response in a wide frequency range. The simulation and statistical results validates that the designed minimum multiplier LWDD circumvents the existing one in terms of minimum absolute magnitude error, mean relative error (dB) and efficient structural realization, thereby making the proposed LWDD a promising approach to digital differentiator design.
2-D DOA Estimation of LFM Signals Based on Dechirping Algorithm and Uniform Circle Array
(Společnost pro radioelektronické inženýrství, 2017-04) Cui, Kaibo; Wu, Weiwei; Chen, Xi; Huang, Jingjian; Yuan, Naichang
Based on Dechirping algorithm and uniform circle array(UCA), a new 2-D direction of arrival (DOA) estimation algorithm of linear frequency modulation (LFM) signals is proposed in this paper. The algorithm uses the thought of Dechirping and regards the signal to be estimated which is received by the reference sensor as the reference signal and proceeds the difference frequency treatment with the signal received by each sensor. So the signal to be estimated becomes a single-frequency signal in each sensor. Then we transform the single-frequency signal to an isolated impulse through Fourier transform (FFT) and construct a new array data model based on the prominent parts of the impulse. Finally, we respectively use multiple signal classification (MUSIC) algorithm and rotational invariance technique (ESPRIT) algorithm to realize 2-D DOA estimation of LFM signals. The simulation results verify the effectiveness of the algorithm proposed.
A Cascaded Reduced-Dimension STAP Method for Airborne MIMO Radar in the Presence of Jammers
(Společnost pro radioelektronické inženýrství, 2017-04) Wang, Ting; Zhao, Yongjun; Chen, Shiwen; Zhang, Kunfan
A cascaded reduced-dimension (RD) space-time adaptive processing (STAP) method for airborne multiple-input multiple-output (MIMO) radar in the presence of jammers is proposed in this paper. The proposed MIMO-STAP method for clutter plus jamming suppression proceeds in two steps. Firstly, the jamming is suppressed by its orthogonal complementary subspace obtained in the passive radar mode, while the receive dimension is reduced. Secondly, the tri-iterative algorithm (TRIA) is utilized to suppress the clutter combining the remaining receive degree of freedom (DOF) with the transmit DOF and the Doppler DOF, and further dimension reduction is implemented. The proposed method can effectively realize the separate jamming and clutter elimination. Moreover, the training sample number and the computational complexity are significantly decreased. Simulation results verify the validity of the proposed cascaded RD MIMO-STAP method under jamming condition.
An Optimal Analysis in Wireless Powered Full-duplex Relaying Network
(Společnost pro radioelektronické inženýrství, 2017-04) Kieu-Tam Nguyen; Dinh-Thuan Do; Voznak, Miroslav
Wireless-powered cellular networks (WPCNs) are currently being investigated to exploit the reliability and improve battery lifetime of mobile users. This paper investigates the energy harvesting structure of the full-duplex relaying networks. By using the time switching based relaying (TSR) protocol and Amplify-and-Forward (AF) model in delay-limited transmission scheme, we propose the closed-form expression of the outage probability and then calculate the optimal throughput. An important result can be taken obviously that the time fraction in TSR, the position of relay, the noise as well as the energy conversation impacting on the outage probability as well as the optimal throughput. By Monte Carlo simulation, the numerical results indicate an effective relaying strategy in full-duplex cooperative systems. Finally, we provide fundamental design guidelines for selecting time fraction in TSR that satisfies the requirements of a practical relaying system.
Wavefront Correction of Ionospherically Propagated HF Radio Waves Using Covariance Matching Techniques
(Společnost pro radioelektronické inženýrství, 2017-04) Zhu, Yongpeng; Wei, Yinsheng; Tong, Peng
High Frequency (HF) radio waves propagating in the ionospheric random inhomogeneous media exhibit a spatial nonlinearity wavefront which may limit the performance of conventional high-resolution methods for HF sky wave radar systems. In this paper, the spatial correlation function of wavefront is theoretically derived on condition that the radio waves propagate through the ionospheric structure containing irregularities. With this function, the influence of wavefront distortions on the array covariance matrix can be quantitatively described with the spatial coherence matrix, which is characterized with the coherence loss parameter. Therefore, the problem of wavefront correction is recast as the determination of coherence loss parameter and this is solved by the covariance matching (CM) technique. The effectiveness of the proposed method is evaluated both by the simulated and real radar data. It is shown numerically that an improved direction of arrival (DOA) estimation performance can be achieved with the corrected array covariance matrix.

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