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Sampling and Exact Reconstruction of pulses with Variable Width

IEEE TRANSACTIONS ON SIGNAL PROCESSING 2017年第10期65卷 2629-2644页

作者： Baechler, Gilles Scholefield, Adam Baboulaz, Loic Vetterli, Martin Ecole Polytech Fed Lausanne Sch Comp & Commun Sci CH-1015 Lausanne Switzerland

Recent sampling results enable the reconstruction of signals composed of streams of fixed-shaped pulses. These results have found applications in topics as varied as channel estimation, biomedical imaging and radio astronomy. However, in many real signals, the pulse shapes vary throughout the signal. In this paper, we show how to sample and perfectly reconstruct Lorentzian pulses with variable width. In the noiseless case, perfect recovery is guaranteed by a set of theorems. In addition, we verify that our algorithm is robust to model mismatch and noise. This allows us to apply the technique to two practical applications: electrocardiogram (ECG) compression and bidirectional reflectance distribution function (BRDF) sampling. ECG signals are one dimensional, but the BRDF is a higher dimensional signal, which is more naturally expressed in a spherical coordinate system;this motivated us to extend the theory to the 2D and spherical cases. Experiments on real data demonstrate the viability of the proposed model for ECG acquisition and compression, as well as the efficient representation and low-rate sampling of specular BRDFs.

关键词： Finite rate of innovation variable width signal sampling signal denoising pulse compression methods spectral analysis electrocardiogram reflectance function specularity

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pulse compression Waveform and Filter Optimization for Spaceborne Cloud and Precipitation Radar

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 2017年第2期55卷 915-931页

作者： Beauchamp, Robert M. Tanelli, Simone Peral, Eva Chandrasekar, V. Colorado State Univ Ft Collins CO 80523 USA CALTECH Jet Prop Lab 4800 Oak Grove Dr Pasadena CA 91109 USA

The optimal design of pulse compression waveform/filter pairs for use with near-nadir spaceborne radar in low earth orbit for the observation of clouds and precipitation is discussed. An optimization technique is introduced that considers performance metrics specific to the remote sensing of clouds and precipitation from such platforms. Specifically, the sensitivity of the radar to precipitation and clouds is maximized as close to the ground as required. The sensitivity of the radar near the surface is typically limited by the pulse compression range sidelobes from the surface's echo. Optimization of the waveform/filter pair's performance is facilitated by a time-domain radar scattering model to simulate radar reflectivity range profiles. The presented radar-scattering model accounts for the radar's configuration constraints and platform motion, as well as the spatial distribution and relative motion of the scatterers. In this paper, the optimization of both linear frequency modulation (LFM) and nonlinear frequency modulation (NLFM) waveforms is considered. It is demonstrated that the LFM waveforms provide superior performance over NLFM waveforms for application subject to unmitigated Doppler shifts.

关键词： Meteorological radar optimization pulse compression methods radar remote sensing radar clutter radar cross-sections spaceborne radar

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High Sensitivity Ultrasonic Inspection Technique Using pulse compression Method

High Sensitivity Ultrasonic Inspection Technique Using Pulse...

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International Symposium on Physical & Failure Analysis of Integrated Circuits

作者： Hiraki Mitsuta Kaoru Sakai Research & Development Group Hitachi Ltd. Kanagawa-ken Japan

ISBN: (纸本)9781538649305

We developed an ultrasonic inspection technique using a pulse compression method for detecting bonding defects with interfaces of stacked wafers. This technique can detect the minute echoes reflected from the bonding interfaces by computing the correlation function between transmitted and received signals. We designed a measurement condition for pulse compression with a transmitted signal and took an ultrasonic measurement of a 3-layer stacked sample. We compared the defect detection sensitivity of the pulse compression method with the ultrasonic inspection using pulse waves. The experimental results showed that the noise of an ultrasonic image was reduced and minute defects could be detected by applying developed method.

关键词： Acoustics pulse compression methods Ultrasonic variables measurement Frequency shift keying Inspection Probes Signal to noise ratio

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Temporal Width of Propagated Electromagnetic pulses in Causal, Dispersive and Absorptive, Dielectrics

Temporal Width of Propagated Electromagnetic Pulses in Causa...

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International Workshop on Antenna Technology - Small Antennas, Innovative Structures, and Applications (iWAT)

作者： Balictsis, Constantinos M. Hellen Telecommun & Post Commiss EETT Telecommun Div Athens Greece

ISBN: (纸本)9781509051779

The unified asymptotic theory provides an accurate description of the field dynamics in (chirped) dispersive electromagnetic pulse propagation of arbitrary initial width in causally dispersive media. The propagated field is a superposition of pulse components whose characteristics are directly related to the dynamical evolution of the saddle points that are relevant in the asymptotic analysis. Here, this theoretical approach is utilized in order to investigate the dependence of the temporal width of the propagated field's envelope on the input field and medium parameters from the sub-cycle to the quasimonochromatic initial pulse regimes.

关键词： Electromagnetic propagation Computational electromagnetics Electromagnetic radiation Electromagnetic transients Ultra wideband radar Chirp Dispersion pulse compression methods pulse shaping methods

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Analysis of the Angular Frequency Dynamics in Chirped Dispersive pulse Propagation

Analysis of the Angular Frequency Dynamics in Chirped Disper...

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IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems (COMCAS)

作者： Balictsis, Constantinos M. Hellen Telecommun & Post Commiss Athens 15125 Greece

ISBN: (纸本)9781538631690

The unified asymptotic approach yields an accurate description of chirped dispersive pulse propagation of arbitrary initial width. The saddle points of the phase function appearing in the exact integral expression of the propagated field are central to the application of this approach. In fact, the dynamics of these saddle points are mapped into the characteristics of the propagated field. Therefore, an analysis of the dependence of the saddle points on the input field and medium parameters and on the propagation distance provides unique theoretical insight on the propagated field characteristics. Here, the procedure for investigating this dependence is elaborated and applied to describe the angular frequency dynamics of the propagated field;the regions of up and down chirp of the instantaneous oscillation frequency are also identified.

关键词： Chirp Computational electromagnetics Dispersion Electromagnetic propagation pulse compression methods pulse shaping methods Ultra-wideband radar

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Chirp design in a pulse compression procedure for the identification of non-linear systems 14

Chirp design in a pulse compression procedure for the identi...

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13th Conference on Ph.D. Research in Microelectronics and Electronics (PRIME) / 14th International Conference on Synthesis, Modeling, Analysis and Simulation methods and Application to Circuit Design (SMACD)

作者： Burrascano, Pietro Laureti, Stefano Senni, Luca Silipigni, Giuseppe Tomasello, Riccardo Ricci, Marco Univ Perugia Dept Engn I-05100 Terni Italy Univ Calabria Dept Informat Modeling Elect & Syst Engn I-87036 Arcavacata Di Rende Italy

ISBN: (纸本)9781509050529

The Hammerstein model of a nonlinear systems can be efficiently identified by means of a technique based on pulse compression. The procedure relies on the properties of the exponential chirps, adopted as excitation signals. The present paper proposes to include the initial phase of the chirp, together with its time duration and frequency extremes, among the parameters to design the excitation signal. Considering this widened set of design parameters, we identify the constraints that the excitation signal must meet to carry out an accurate identification. The paper shows that introducing the initial phase as further degree of freedom, adds flexibility to the design process and allows for the use of much shorted chirp signals, making measurements faster and reliable. The experimental results reported demonstrate the validity of the constraints identified and show that, choosing appropriate combinations of the parameters, very short chirp accomplish the phase constraint needed for an accurate modelling of the non-linear system.

关键词： system modeling and identification nonlinear systems pulse compression methods chirp

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Fast Cross-Correlation Mitigation via Minimum Mean-Square Error Estimation Based on Matched Filter Outputs for Consecutive DSSS Signals

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IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 2016年第4期52卷 2044-U1111页

作者： Shen, Yuyao Wang, Yongqing Yu, Xiuli Wu, Siliang Beijing Inst Technol Sch Informat & Elect 5 YardZhongguancun South St Beijing Peoples R China Beijing Inst Astronaut Syst Engn Beijing Peoples R China

In the direct sequence spread spectrum (DSSS) system, multiple-access interference mitigation is critical to improving the acquisition performance. Therefore, in this paper, a fast cross-correlation mitigation algorithm based on the minimum mean-square error criterion is proposed. The algorithm exploits the matched filter outputs;hence, it is applicable to existing DSSS receivers based on direct pseudorandom noise code correlation. Essentially, the proposed scheme is an adaptive filter that optimizes each individual uncertain code phase delay. The algorithm employs both the code sequence information of the desired signal and that of the multiple-access interference signal, which enables it to outperform the standard matched filter, conventional least-mean-squares algorithm, and the pulse compression repair method. Furthermore, the proposed algorithm decreases the computational load compared with the existing multistatic adaptive pulse compression method by reducing the stage-number of the adaptive filter;this results in a slight degradation in performance. Numerical results verify the validity of the proposed algorithm.

关键词： Multiple access interference Error analysis Mean square error algorithms matched filters direct sequence spread spectrum Self tuning pulse compression methods Cross correlation desired signal mean-square error criterion

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Concept for pulse compression Device Using Structured Spatial Energy Distribution

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IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES 2016年第3期64卷 742-755页

作者： Tamma, Venkata Ananth Figotin, Alexander Capolino, Filippo Univ Calif Irvine Dept Elect Engn & Comp Sci Irvine CA 92697 USA Univ Calif Irvine Dept Math Irvine CA 92697 USA

We explore a novel concept for pulse compression scheme applicable at RF, microwave, and possibly up to optical frequencies based on structured energy distribution in cavities supporting degenerate band-edge (DBE) modes. We show the high spatial concentration of energy due to DBE modes and proper choice of boundary conditions in coupled transmission lines (TLs) provide the basis for superior performance of the structured cavity when compared to a conventional cavity. We investigate the novel cavity features: larger loaded quality factor of the cavity and stored energy compared to conventional designs, robustness to variations of cavity loading, energy feeding and extraction at the cavity center, and substantial reduction of the cavity size by use of equivalent lumped circuits for low-energy sections of the cavity. Structured energy also allows for controlled pulse shaping via engineered extraction techniques. The presented concepts are general, in terms of equivalent coupled TLs, and can be applied to a variety of realistic guiding structures. Potential applications include microwave pulse compression devices, on-chip millimeter-wave pulse generation, and pulsed laser generation.

关键词： Cavity resonators high-power microwave generation optical pulse compression photonic-bandgap structures pulse compression methods Q-factor

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High-Frame-Rate Synthetic Aperture Ultrasound Imaging Using Mismatched Coded Excitation Waveform Engineering: A Feasibility Study

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IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL 2016年第6期63卷 828-841页

作者： Lashkari, Bahman Zhang, Kaicheng Mandelis, Andreas Univ Toronto Dept Mech & Ind Engn Ctr Adv Diffus Wave Technol Toronto ON M5S 3G8 Canada

Mismatched coded excitation (CE) can be employed to increase the frame rate of synthetic aperture ultrasound imaging. The high autocorrelation and low cross correlation (CC) of transmitted signals enables the identification and separation of signal sources at the receiver. Thus, the method provides B-mode imaging with simultaneous transmission from several elements and capability of spatial decoding of the transmitted signals, which makes the imaging process equivalent to consecutive transmissions. Each transmission generates its own image and the combination of all the images results in an image with a high lateral resolution. In this paper, we introduce two different methods for generating multiple mismatched CEs with an identical frequency bandwidth and code length. Therefore, the proposed families of mismatched CEs are able to generate similar resolutions and signal-to-noise ratios. The application of these methods is demonstrated experimentally. Furthermore, several techniques are suggested that can be used to reduce the CC between the mismatched codes.

关键词： Chirp modulation frequency modulation (FM) matched filters pulse compression methods synthetic aperture radar synthetic aperture sonar

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Data compression for Snapshot Mosaic Hyperspectral Image Sensors

Data Compression for Snapshot Mosaic Hyperspectral Image Sen...

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European Signal Processing Conference

作者： George Tzagkarakis Wouter Charle Panagiotis Tsakalides Institute of Computer Science (ICS) - Foundation for Research and Technology-Hellas (FORTH) IMEC

ISBN: (纸本)9781509018918

Recent achievements in hyperspectral imaging (HSI) demonstrated successfully a novel snapshot mosaic sensor architecture, enabling spectral imaging in a truly compact way. Integration of this new technology in handheld devices necessitates efficient compression of HSI data. However, due to the specific mosaic structure of the acquired images, traditional compression methods tailored to full-resolution HSI data cubes fail to exploit the special spatio-spectral interrelations among the pixels. This paper introduces an efficient and computationally tractable compression technique for mosaic HSI images. Specifically, an appropriate decorrelator is constructed for exploiting the spatio-spectral redundancies among the pixels, by modeling the filters arrangement on the mosaic HSI sensor as a multiple-input multiple-output antenna array. Doing so, the decorrelator depends only on the sensor and not on the data to be compressed. Comparison with state-of-the-art compression methods designed for HSI data cubes reveals that our approach achieves better reconstruction quality at lower bits-per-pixel rates.

关键词： Hyperspectral data Snapshot mosaic hyperspectral sensor Image compression Spatio-spectral decorrelation Data compression Image compression AKR1B10 gene decorrelator mosaic pattern Patchy burn Mosaic Sensors hyperspectral imagery Snapshots pixel data cubes image compression method data compression method pulse compression methods

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