Time filter

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Zhao Y.,Zhengzhou University | Zhao Y.,National Key Laboratory of Blind Signals Processing | Luo S.-E.,National Key Laboratory of Blind Signals Processing | Wan J.,National Key Laboratory of Blind Signals Processing
International Conference on Signal Processing Proceedings, ICSP | Year: 2010

In the broadband communication systems, signals in intermediate frequency (IF) bandwidth usually have nonequal bandwidths and arbitrary carriers. The channelization architecture based on subband filterbanks is an efficient realization method to channelization these signals. The performance analysis of this channelization architecture is proposed in this paper. A channelization structure using complex-valued subband filterbanks is given out firstly, and the mathematic model of this structure is established. Then the channelization process is deduced theoretically and the expressions of channelization results are obtained. These expressions are divided into some addition terms, the error causations can be attained by analyzing these addition terms. Three error parameters are defined to describe different kinds of distortions. Simulations are carried out under the given channelization structure, and the results demonstrate the rationality of the deduction conclusions. This performance analysis method are also helpful on designing the optimal subband filterbanks for channelization. © 2010 IEEE.


Yuan X.-H.,National Key Laboratory of Blind Signals Processing | Zhang G.-G.,National Key Laboratory of Blind Signals Processing | Zheng H.,National Key Laboratory of Blind Signals Processing
2012 IEEE International Conference on Information and Automation, ICIA 2012 | Year: 2012

This paper analyzes the effect of large scale ionospheric tilts on the errors of single site location by establishing a simplified model for large scale ionospheric tilts in a three-dimensional coordinate. An equation including the coordinate of the reflection point and a numerical resolution to the equation based on Newton-Raphson iterative algorithm are given. Then the curves of error of single site location versus tilts angle, direction and target range is given by simulations. © 2012 IEEE.


Yongcheng W.,National Key Laboratory of Blind Signals Processing | Ling Y.,National Key Laboratory of Blind Signals Processing | Liang M.,National Key Laboratory of Blind Signals Processing
Proceedings - 7th International Conference on Intelligent Information Hiding and Multimedia Signal Processing, IIHMSP 2011 | Year: 2011

This paper proposes a novel approach for frame synchronization which applies Maximum Likelihood Ratio Testing (MLRT) coupled to Post Detection Integration (PDI) scheme. This approach is robust to frequency and phase offsets, meanwhile it considers base band signal over sampling without matched filtering and perfect timing. Derivation and realization diagram of this approach is presented. Numerical simulation results show that this method outperforms existing PDI schemes and Choi-Detector[3]. © 2011 IEEE.


Zhao P.-Y.,National Key Laboratory of Blind Signals Processing | Song K.-K.,National Key Laboratory of Blind Signals Processing | Cao W.-Q.,National Key Laboratory of Blind Signals Processing | Peng H.-F.,National Key Laboratory of Blind Signals Processing
Journal of Beijing Institute of Technology (English Edition) | Year: 2015

Optimization of the search fence's parameters is significant for improving phased array radar's resource manages efficiency and capture capability on space debris. Firstly, based on the spatial geometric relationships, the formula of space debris fence-crossing time is derived. Secondly, considering the influence of the beam widening on radar detection ability, quantitative analysis of the different radar pulse width on the different beam positions is made. Finally, using orbit elements and radar cross section of actual space debris, comparison of capture capability of search fence with different parameters is made by simulation. Numerical simulation shows that the search pattern with “wide fence and short pulse” can effectively promote the capture capability on space debris. © 2015 Beijing Institute of Technology.


Wang Y.,National Key Laboratory of Blind Signals Processing | He L.,National Key Laboratory of Blind Signals Processing
Proceedings - 2014 IEEE Workshop on Advanced Research and Technology in Industry Applications, WARTIA 2014 | Year: 2014

Estimating network topology is a non-trivial task. Different from the state-of-art methods such as traceroute-like active probing, network tomography and network protocols analysis based passive measurement, this work proposes a novel method to estimate the network hidden topology using time to live (TTL) values extracted from IP packets. TTL contains the information about hops of the forward paths which can be fused to reconstruct the topology. The proposed estimating algorithm is described and its performance is illustrated using topology simulation data. Experimental results demonstrate the effectiveness of the newly developed technique. © 2014 IEEE.


Liu C.-G.,National Key Laboratory of Blind Signals Processing | Li L.-Z.,National Key Laboratory of Blind Signals Processing | Zhang X.-Y.,National Key Laboratory of Blind Signals Processing
2010 Global Mobile Congress, GMC'2010 | Year: 2010

In this paper, an improved carrier frequency offset estimation method which is less sensitive to timing offset is proposed. The method is based on the carefully constructed frequency domain sequence and the correlation operation. Then, we analyze the performances of our newly proposed estimation metric over different wireless channel conditions by Monte Carlo simulations. Finally, according to the training symbols of IEEE 802.16d, our simulation results show that the newly proposed method can overcome the relatively large influences introduced by timing offset, and at the same time, it may perform better than the conventional methods without increasing algorithm's complexity. © 2010 IEEE.


Xin J.-R.,National University of Defense Technology | Xin J.-R.,National Key Laboratory of Blind Signals Processing | Lu L.-X.,National Key Laboratory of Blind Signals Processing | Bao X.,National Key Laboratory of Blind Signals Processing | Cheng J.,National Key Laboratory of Blind Signals Processing
Tien Tzu Hsueh Pao/Acta Electronica Sinica | Year: 2014

Noise estimation is the basis of the adaptive blind signal detection. It provides the thresholds of automatic detector based on the CFAR (Constant False Alarm Rate) rule. The traditional noise estimator was complicated and cannot be easily implemented in the on-line blind signal processing system for the satellite broadband frequency-hopping signal. Utilizing the sparseness of the frequency-hopping signal, a new algorithm was proposed to facilitate the noise estimation. The reliability and complexity of the algorithm was analyzed theoretically, and the effectiveness was verified through both simulations and real signal experiments. Compared to the classical algorithm, the proposed algorithm can provide similar noise estimation results, while its computational complexity and buffer consumption was significantly reduced. ©, 2014, Tien Tzu Hsueh Pao/Acta Electronica Sinica. All right reserved.


Liu C.-G.,National Key Laboratory of Blind Signals Processing | Li L.-Z.,National Key Laboratory of Blind Signals Processing
Xitong Fangzhen Xuebao / Journal of System Simulation | Year: 2012

The effects of carrier frequency offset on cross-correlation based timing algorithm were analyzed theoretically and an improved timing algorithm was proposed. The new method was neither sensitive to frequency offset nor dependable on the concrete preamble structure. Then, the distribution performances of the expectations and variances of the newly proposed timing metric were analyzed over different wireless channels through Monte-Carlo simulations. The algorithm was applied in IEEE 802.16d system and simulations were carried out. The simulation results show that the new method is less sensitive to frequency offset, and the timing effect is very accurate. © copyright.


Yan Z.,Zhengzhou University | Yan Z.,National Key Laboratory of Blind Signals Processing | Luo S.-E.,National Key Laboratory of Blind Signals Processing | Jian W.,National Key Laboratory of Blind Signals Processing
2010 6th International Conference on Wireless Communications, Networking and Mobile Computing, WiCOM 2010 | Year: 2010

In modern broadband software defined radio systems, there usually exist several independent signals in the received intermediate frequency (IF) bandwidth. They have nonequal bandwidths and arbitrary band locations, which are unknown and time-variant. In order to efficiently channelize these signals, an adaptive channelization method is proposed based on complex-valued oversampled subband filterbanks. The IF signal is decomposed by uniform analysis filterbanks firstly. Then the signals' distribution is obtained according to the power estimations of every sub-signal. At last, the desired signals are extracted by merging the corresponding sub-signals using synthesis filterbanks. When the signals' distribution changes, the synthesis scheme is updated adaptively to channelize new signals without altering subband filterbanks. Polyphase decomposition are adopted to optimize the channelization method and reduce the computational complexity. Simulations are carried out to testify the reliability and efficiency of the proposed scheme. © 2010 IEEE.


Huang Y.-L.,National Key Laboratory of Blind Signals Processing | Lu Y.-R.,National Key Laboratory of Blind Signals Processing | Yuan Q.,National Key Laboratory of Blind Signals Processing
Dianzi Yu Xinxi Xuebao/Journal of Electronics and Information Technology | Year: 2010

Burst detection plays a crucial role for burst-mode demodulation, which helps the acquisition and synchronization of data bursts. Most conventional Data-Aided (DA) burst detection approaches demands timing, and the performance degrades severely in the presence of frequency offset. This paper proposes a burst detection algorithm based on the Average-Likelihood-Ratio-Test (ALRT) for over-sampled modulated signals with timing uncompleted. The proposed algorithm outperforms the previously proposed algorithms and is robust to the frequency offset. Furthermore, the dependence of false alarm rate on SNR is slight.

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