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European Signal Processing Conference

作者： Nhut Minh Ngo Brian Michael Kurkoski Masashi Unoki School of Information Science Japan Advanced Institute of Science and Technology

ISBN: (纸本)9781479988518

This paper proposes an audio watermarking method based on dynamic phase coding and error control coding. The technique of quantization index modulation is employed for embedding watermarks into the phase spectrum of audio signals. Since most of the audio information is distributed in moderately low frequencies, to increase robustness, this frequency region is chosen for embedding watermarks. phase modification causes sound distortion in a manner that is proportional to the magnitude. Therefore, the amount of phase modification is adjusted according to the magnitude to balance inaudibility and robustness. Error control coding is incorporated to further increase reliability of watermark detection. The experimental results show that the watermarks could be kept inaudible in watermarked signals and robust against various attacks. Error control coding is effective in increasing watermark detection accuracy remarkably.

关键词： Audio watermarking Quantization index modulation Inaudibility Robustness Error control coding Error correction codes Watermarking Robustness Digital watermarking ERROR CONTROL phase spectrum Audio phase coding audio signals embedding

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Correction of velocity estimation bias caused by phase-shift beamforming in acoustic Doppler velocity logs

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IET RADAR SONAR AND NAVIGATION 2024年第7期18卷 1116-1131页

作者： Jia, Kuankuan Xu, Weijie Ma, Li Chinese Acad Sci Shanghai Acoust Lab Shanghai Peoples R China Chinese Acad Sci Inst Acoust Beijing Peoples R China Chinese Acad Sci Key Lab Underwater Acoust Environm Beijing Peoples R China Univ Chinese Acad Sci Beijing Peoples R China

The performance of Doppler velocity logs (DVLs) in terms of velocity estimate error is directly linked to the geometry of the beam and the pulse transmitted. Beyond a specific transmitted bandwidth, the phase-shift beamformer can introduce significant errors in velocity estimation. To delineate the operating mechanism of phase-shift errors within a phased array of acoustic DVLs, the correlation between bottom echo and velocity distribution, in conjunction with the power-weighted function, was initially examined predicated on spectral estimation theory. Subsequently, numerical and analytical models of the Gaussian-shaped Doppler spectrum were formulated. The models are employed to evaluate the velocity estimation inaccuracies attributed to phase shifts in extant DVLs, and the comparative results with field experiments corroborate the model's efficacy in forecasting errors. The theoretical findings evaluate the performance limitations of the current phased array transducer design and provide insights for developing new designs. Pool experimental results show that this design effectively reduces the velocity estimation error caused by phase shift under static conditions and in the presence of Doppler frequencies to a level of almost complete elimination of the error compared to conventional configurations. The bandwidth of the transmitted signal affects the long-term accuracy of Doppler velocity logs (DVL) navigation. The mechanism of phase-shift error action in phased-array DVLs is clarified. A novel design of DVLs based on a time-delay beamformer is expected to eliminate the phase-shift error. image

关键词： acoustic arrays Doppler measurement Doppler shift marine navigation phase coding sonar signal processing velocity measurement

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Sidelobe Suppression Method with Improved CLEAN Algorithm for Pulse Compression OTDR

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IEEE PHOTONICS TECHNOLOGY LETTERS 2024年第22期36卷 1321-1324页

作者： Huang, Yi Chen, Xiaofeng Shen, Wei Wei, Ziyi Hu, Chengyong Deng, Chuanlu Wang, Lisen Zhang, Qi Chen, Wei Zhang, Xiaobei Chen, Lin Jin, Wei Tang, Jianming Wang, Tingyun Shanghai Univ Key Lab Specialty Fiber Opt & Opt Access Networks Shanghai 200444 Peoples R China Shanghai Univ Elect Power Coll Elect & Informat Engn Shanghai 200090 Peoples R China Bangor Univ Sch Elect Engn Bangor LL57 1UT Wales

Although pulse compression optical time domain reflectometry (PC-OTDR) exhibits high performance in spatial resolution and dynamic range, it inevitably introduces auto-correlation sidelobes, potentially impacting measurement accuracy. In this letter, an improved CLEAN algorithm is proposed to efficiently suppress sidelobes and enhance the peak-to-sidelobe ratio (PSLR) of signals in PC-OTDR. The proposed method introduces an adaptive step factor instead of the traditional fixed factor to reduce the number of iterations. Compared to the traditional method, the proposed method achieves a 2.87 dB improvement of PSLR from a 10 km sensing fiber. In addition, the computation time cost is significantly reduced, which is 1.92 s less than that of the traditional CLEAN algorithm.

关键词： Encoding Optical fibers Spatial resolution Signal to noise ratio Perturbation methods Optical filters Filtering Pulse compression optical time domain reflectometry (PC-OTDR) phase coding CLEAN algorithm sidelobe suppression

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Neural coding of space by time

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BIOLOGICAL CYBERNETICS 2024年第3-4期118卷 215-227页

作者： Loeffler, Hubert Gupta, Daya Shankar Bahmer, Andreas South Univ Savannah GA 31406 USA RheinMain Univ Appl Sci Ruesselsheim Campus D-65197 Wiesbaden Germany

The intertwining of space and time poses a significant scientific challenge, transcending disciplines from philosophy and physics to neuroscience. Deciphering neural coding, marked by its inherent spatial and temporal dimensions, has proven to be a complex task. In this paper, we present insights into temporal and spatial modes of neural coding and their intricate interplay, drawn from neuroscientific findings. We illustrate the conversion of a purely spatial input into the temporal form of a singular spike train, demonstrating storage, transmission to remote locations, and recall through spike bursts corresponding to Sharp Wave Ripples. Moreover, the converted temporal representation can be transformed back into a spatiotemporal pattern. The principles of the transformation process are illustrated using a simple feed-forward spiking neural network. The frequencies and phases of Subthreshold Membrane potential Oscillations play a pivotal role in this framework. The model offers insights into information multiplexing and phenomena such as stretching or compressing time of spike patterns.

关键词： phase coding Subthreshold membrane potential oscillation Sharp wave ripples Time warping Temporal memory

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phase-coded radar waveform design with quantum annealing

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IET RADAR SONAR AND NAVIGATION 2024年第3期18卷 532-540页

作者： Presles, Timothe Enderli, Cyrille Burel, Gilles Baghious, El Houssain Thales Def Mission Syst Elancourt France Univ Brest Lab STICC CNRS Brest France

The Integrated Side Lobe Ratio (ISLR) problem the authors consider here consists in finding optimal sequences of phase shifts in order to minimise the mean squared cross-correlation side lobes of a transmitted radar signal and a mismatched replica. Currently, ISLR does not seem to be easier than the general polynomial unconstrained binary problem, which is NP-hard. In their work, the authors aim to take advantage of the scalability of quantum computing to find new optima, by solving the ISLR problem on a quantum annealer. This quantum device is designed to solve quadratic optimisation problems with binary variables (QUBO). After proposing suitable formulation for different instances of the ISLR, the authors discuss the performances and the scalability of their approach on the D-Wave quantum computer. More broadly, their work enlightens the limits and potential of the adiabatic quantum computation for the solving of large instances of combinatorial optimisation problems. The Integrated Side Lobe Ratio (ISLR) problem the authors consider here consists in finding optimal sequences of phase shifts in order to minimise the mean squared cross-correlation side lobes of a transmitted radar signal and a mismatched replica. Currently, ISLR does not seem to be easier than the general polynomial unconstrained binary problem, which is NP-hard. In their work, the authors aim to take advantage of the exponential scalability of quantum computing to find new optima, by solving the ISLR problem on a quantum ***

关键词： optimisation phase coding radar waveforms

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Terahertz beam shaping using space-time phase-only coded metasurfaces

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NANO COMMUNICATION NETWORKS 2024年 42卷

作者： Masouleh, Sahar Solati Hosseininejad, Seyed Ehsan Babol Noshirvani Univ Technol Fac Elect & Comp Engn Babol 47148 Iran

Digital metasurfaces as space-coded surfaces composed of a set of sub-wavelength meta-atoms enable extraordinary capabilities to manipulate electromagnetic waves. Recently, amplitude-phase-joint-coding metasurfaces have been proposed to achieve enhanced beam shaping. However, design of a unit cell structure with a full manipulation of amplitude and phase of the reflected beam is challenging and this kind of unit cell structures are complicated. This paper proposes a space-time phase-only metasurface based on simple graphene-based unit cell that is digitally coded and arranged with a specific time sequence, allowing the effective simultaneous manipulation of both phase and amplitude. In this way, it is demonstrated that the terahertz beam can be shaped using the proposed metasurface.

关键词： Beam shaping Space-time metasurface phase coding Terahertz

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A DFRC Based on Multichannel and Spatial Information Fusion for Multiradar Communication

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IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS 2024年第5期23卷 1423-1427页

作者： Li, Songyi Liu, Zhenyu Guangdong Univ Technol Sch Informat Engn Guangzhou 510006 Peoples R China

Two problems have to be faced in the multiradar communication scenario. One problem is that the coupling of the sensing signal and the communication signal leads to the deterioration of dual-function performance. Another problem is that the confused localization of active and passive targets prevents the radar from identifying the actual communication resources. This letter proposes a novel sensing-centric dual-function radar-communication (DFRC) mechanism including multichannel (MC) scheme and spatial information fusion (SIF) scheme, named MCSIF-DFRC. For the coupling problem, according to the frequency characteristics caused by the propagation difference between the sensing signal and the communication signal, an MC scheme based on frequency analysis and separation is designed. For the confusion problem, since the direct communication signal and the reflected sensing signal from the same active target have consistency in spatial dimension, a SIF scheme of joint dual-function signals based on angle spectrum analysis and spatial information association is designed. The simulations indicate that the MCSIF-DFRC performs better on the ambiguity function and the interference probability by comparing it with some DFRC methods. The experiments prove the feasibility of the proposed mechanism to sense and communicate in the multiradar scenario.

关键词： Sensors Radar Chirp Encoding Couplings Decoding Azimuth Dual-function radar communication (DFRC) frequency-modulated continuous wave (FMCW) radar multiple-input-multiple-output phase coding waveform propagation

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Smoothed phase-Coded FMCW: Waveform Properties and Transceiver Architecture

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IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 2023年第2期59卷 1720-1737页

作者： Kumbul, Utku Petrov, Nikita Vaucher, Cicero S. Yarovoy, Alexander Delft Univ Technol Fac Elect Engn Microwave Sensing Syst & Signals Grp MS3 NL-2628 CD Delft Netherlands NXP Semicond NV NL-5656 AG Eindhoven Netherlands Delft Univ Technol Delft Netherlands

Smoothed phase-coded frequency modulated continuous waveform (SPC-FMCW), which is aimed to improve the coexistence of multiple radars operating within the same frequency bandwidth, is studied, and the receiving strategy with a low analog-to-digital converter sampling requirement is investigated. The Gaussian filter is applied to obtain smooth waveform phase transitions, and then, quadratic phase lag compensation is performed before waveform transmission to enhance decoding. The proposed waveform is examined in different domains, and its waveform properties are analyzed theoretically and demonstrated experimentally. Both simulation and experimental results show that the introduced waveform with the investigated processing steps helps combine all advantages of the FMCW waveform, including hardware simplicity and small operational bandwidth of the receiver, with the advantages of phase coding.

关键词： Radar Delays Bandwidth Sensors Frequency modulation Codes Encoding Automotive radar Gaussian minimum shift keying (GMSK) Gaussian smoother mutual orthogonality phase-coded frequency-modulated continuous waveform (PC-FMCW) phase coding

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Generation of phase-Coded LFM Signals Based on Fourier Domain Mode-Locked Optoelectronic Oscillator

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JOURNAL OF LIGHTWAVE TECHNOLOGY 2023年第19期41卷 6142-6148页

作者： Gou, Weilei Wang, Lin Liu, Yifan Chen, Yu Yu, Yuan Yu, Yu Zhang, Xinliang Huazhong Univ Sci & Technol Wuhan Natl Lab Optoelect Wuhan 430074 Peoples R China Huazhong Univ Sci & Technol Sch Opt & Elect Informat Wuhan 430074 Peoples R China Opt Valley Lab Wuhan 430074 Peoples R China

phase-coded linearly frequency modulated (LFM) signals play essential roles in enhancing the performance of radar as well as exploring wireless communication. To generate phase-coded LFM signals, we propose to launch a phase-coded signal into an optoelectronic oscillator (OEO). When the OEO is Fourier domain mode-locked (FDML), a phase-coded LFM signal is generated. The center frequency, bandwidth, coding pattern, and bit rate of the generated signals can be flexibly adjusted. In the experiment, a phase-coded LFM microwave signal with a bandwidth of 5.0 GHz is generated, corresponding to a time bandwidth product (TBWP) of 2.8 x 10(5). The center frequency and bandwidth of the generated signals are adjusted from 9.7 to 10.7 GHz and from 5.0 to 3.0 GHz, respectively. Meanwhile, different coding patterns and rates are also implemented, indicating that the phase-coded LFM signal can be used in wireless communications. The proposed approach can potentially be applied to multifunctional integration in radar.

关键词： Frequency modulation Encoding Optical polarization Bandwidth Optical modulation Microwave oscillators phase modulation Fourier domain mode-locked optoelectronic oscillator linearly frequency modulated signal multifunctional radar system phase coding pulse compression

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A Compound ECCM Technique for FMCW Radars

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IEEE ACCESS 2023年 11卷 62942-62954页

作者： Eser, Dogancan Demir, Simsek Koc, Sencer Middle East Tech Univ Dept Elect & Elect Engn TR-06800 Ankara Turkiye

This paper presents a compound electronic counter-countermeasure (ECCM) technique for frequency-modulated continuous-wave (FMCW) radars to counter electronic countermeasure (ECM) techniques such as coherent spoofing, non-coherent spoofing, and digital radio frequency memory (DRFM) jamming. The proposed technique is based on phase coding in slow time and checking the initial phase of the baseband return signal. A measurement setup was built and operated between 4.3-4.5 GHz for experimental validation. An RF cable of length 12 m was used to emulate the target. The experimental results were analyzed using MATLAB to demonstrate the effectiveness of the ECCM technique in different jamming scenarios. The results indicate that the proposed ECCM technique using phase coding can provide a satisfactory performance in different jamming scenarios. The proposed ECCM technique offers several advantages over existing methods. First, the technique does not entail any frequency bin changes in slow time period, thereby conferring processing benefits. Second, it poses challenges to jammer system in terms of predicting the initial phase of the beat signal. The proposed technique is expected to provide better protection against malicious attacks for FMCW radars.

关键词： ~Coherent spoofing digital radio frequency memory (DRFM) electronic counter-counter measure (ECCM) frequency-modulated continuous-wave (FMCW) radar phase coding

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