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6th International Conference on Anti-Counterfeiting, Security and Identification (ASID)

作者： Hou, Fang Xiamen Univ Sch Informat Sci & Techol Xiamen 361005 Peoples R China

ISBN: (纸本)9781467321433

time-frequency coding modulation shows strong ability against fast fading in wireless channel, study on it used in underwater acoustic communication progressed in recent years. Performances of different time-frequency codeword group vary greatly. Marine underwater acoustic channel is sparse multipath channel with random delay, this paper presents three points about time-frequency coding principle used in it, and accordingly wrote a searching program based on backtracking algorithm so as to find out code groups with different property quickly and reliably. In this article the problem of searching for eligible code groups is detailedly analysed, then searching algorithm is derived from it, finally the algorithm is realized and running flowchart is given.

关键词： underwater acoustic communication time-frequency coding backtracking algorithm

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Weak-coherent-state-based time-frequency quantum key distribution

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JOURNAL OF MODERN OPTICS 2015年第20期62卷 1713-1721页

作者： Zhang, Yequn Djordjevic, Ivan B. Neifeld, Mark A. Univ Arizona Dept Elect & Comp Engn Tucson AZ 85721 USA

We study large-alphabet quantum key distribution (QKD) based on the use of weak-coherent states and the time-frequency uncertainty relation. The large alphabet is achieved by dividing time and spectrum into M bins resulting in a frame similar to traditional pulse-position modulation (in time domain). However, the non-uniform occurrence of a photon prepared in a time/frequency bin creates the space for eavesdropping. By analysis, we show that a new intercept-resend attack strategy exists, which is stronger than that has been reported in the literature and hence the secret key rate of time-frequency QKD (TF-QKD) can be more tightly bounded. We then analyse the secret key rates of TF-QKD under various practical issues, such as channel loss, background noise, jitter and atmospheric turbulence in order to better understand the applicability of TF-QKD. Further, we discuss the information reconciliation for TF-QKD. Specifically, we investigate the layered coding scheme for TF-QKD based on quasi-cyclic low-density parity-check codes against jitter and atmospheric turbulence. By simulation, we demonstrate that information reconciliation can be efficiently achieved.

关键词： quantum key distribution time-frequency coding pulse-position modulation low-density parity-check codes atmospheric turbulence

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time–frequency coding via Wavelets Analysis for Bursting Spikes of Neuron Firing

Time–Frequency Coding via Wavelets Analysis for Bursting Sp...

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The 2nd International Conference on Bioinformatics and Biomedical Engineering(iCBBE 2008)(第二届生物信息与生物医学工程国际会议)

作者： Xin Tian Xinling Geng Tianjin Research Centre of Basic Medicine Department of Biomedical Engineering Tianjin Medical Unive Department of Biomedical Engineering Tsinghua University Beijing China

Bursting (spikes) shows very complex dynamics of firing activities of the neurons. The aim of this study is to investigate the coding details in time-frequency domain for bursting spikes using wavelet analysis, which will give a combinative neural code from both time and frequency domains. Data in this study is two types of the spikes: bursting and spiking simulatied from Chay model via 4-order R-K algorithm under different tasking conditions. The interspike intervals (ISI) are obtained through the spike series used for the neural coding. Mexican Hat ('mexh') wavelet is selected as mother wavelet used in this study. Neural coding of bursting under a 5-scale decomposition is performed and compared to that from temporal coding. The results of this study have demonstrated that time-frequency coding might be a more useful approach, and provide more details to neural coding for the bursting spikes than rate coding and temporal coding.

关键词： bursting spikes time-frequency coding wavelets

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time frequency coding in underwater acoustic communication

Time frequency coding in underwater acoustic communication

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MTS/IEEE Conference on Celebrating the Past - Teaming Toward the Future

作者： Wang, Y Northwestern Poly-Technical Univ. China

ISBN: (纸本)0933957300

Due to the difficulties encountered in underwater acoustic communication channels, the most prominent of which is considered to be the multipath propagation. This paper proposes to use the time-frequency coding for underwater acoustic communication system in which there is serious multipath interference of transmitted signal. This paper is divided into three parts. The first part gives a brief overview of characteristics of UWA communication channels and presents communication channel modeling, which uses ray tracing for determining the multipath structure. The second part is devoted to communication system design, which uses different frequency sequence over different time slot being well known as two-dimensional coding. Finally, the third part summarizes the conclusions. The system based on this principle has good performance against multipath interference and can obtain a high data transmission rate. The computer simulation shows that successful signal transmission of 25 bit/s date rate, over 5 km distance and at 0dB signal to noise ratio, can be achieved, the error coding probability is very low.

关键词： acoustic channel multi-path transmission time-frequency coding

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A medical acoustic signal analysis method based on Zipf law 14

A medical acoustic signal analysis method based on Zipf law

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14th International Conference on Digital Signal Processing (DSP 2002)

作者： Dellandrea, E Makris, P Vincent, N Boiron, M Lab Informat F-37200 Tours France

ISBN: (纸本)0780375033

We present in this paper a medical signal analysis method that we have developed in order to study, in an atraumatic and non invasive way, the inferior oesophageal sphincter behaviour. This one plays an important part in the gastro-oesophageal reflux phenomenon. The proposed method is more efficient and is better suited to our problem than traditional signal processing methods that did not give good results. It has a double originality. The first one lies on the audio signal coding, based on its time-frequency representation, and allowing the extraction of a set of ordered words that makes up a text. The second one lies on the use of the Zipf law as an analysis tool. The parameters obtained from the Zipf law observation allow to automatically detect and characterize signal regions of interest, which are periods while happen xiphoidal sounds (produced when a bolus, a small quantity of baryte, crosses the inferior oesophageal sphincter). Thus, the results permit to evaluate the sphincter capability, which is a precious help for specialists.

关键词： Zipf law time-frequency coding medical acoustic signal

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PERFECT BINARY ARRAYS WITH 36 ELEMENTS

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ELECTRONICS LETTERS 1987年第14期23卷 730-732页

作者： BOMER, L ANTWEILER, M Institute of Electrical Communication Technical University of Aachen Aachen West Germany

The letter presents a new two-dimensional binary array with a perfect periodic autocorrelation function (PACF). Four decompositions of the new array in two-, three- and four-dimensional arrays with the same property are shown. These can be applied, for example, in time-frequency coding, two-dimensional synchronisation and image coding.

关键词： two-dimensional synchronisation two-dimensional binary array 3D arrays four-dimensional arrays perfect periodic autocorrelation function encoding image coding Codes synchronisation time-frequency coding decompositions Optical information, image and video signal processing Information theory information theory picture processing

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