The frequency-modulated continuous-wave (FMCW) radar is an alternative to the pulse when distance target short. Typical FMCW implementations have a homodyne architecture transceiver which limits performances for short-range applications: beat frequency can be relatively small and placed in range affected by specific issues (dc offset, self-mixing, 1/f noise). In addition, one classical problem of that voltage-controlled oscillator adds certain degree nonlinearity cause dramatic resolution...

Compressive sensing has emerged as an area that opens new perspectives in signal acquisition and processing. It appears alternative to the traditional sampling theory, endeavoring reduce required number of samples for successful reconstruction. In practice, compressive aims provide saving resources, transmission, storage capacities facilitate processing circumstances when certain data are unavailable. To end, relies on mathematical algorithms solving problem reconstruction from a greatly...

A time-frequency classifier is applied for human gait classification. Time-frequency (t-f) quadratic distributions are used signal representations. Three specific motions considered, corresponding to three different scenarios of arm which describe free and confined swings. The microDoppler signature in the domain each motion style viewed as a feature incorporated distance-based classifications measured between test data t-f distribution training average distributions. It shown that performs...

Abstract With the development of power distribution systems demands, grid reliability becomes a strategic issue. Continuous monitoring transmission networks is key component in addressing this Partial discharge (PD) characterisation instruments provide reliable solution and an important indicator state cable insulation. An increase PD level usually indicates fault that affects integrity can lead to various problems related quality quantity transmitted energy. In context, use Internet Things...

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This paper introduces a new generalized complex-lag moment which produces joint time-"phase derivatives" distributions. For the choice of time-"first-order phase derivative," stands for time–frequency representation, this distribution can be seen as form Wigner–Ville distribution. Moreover, generalization leads to distributions with highly reduced inner interferences caused by nonlinearity...

In this paper, we apply Multiple-Input Multiple-Output (MIMO) configurations to Moving Target Identification (MTI) for urban sensing using radars. particular, consider MIMO-MTI formulations detecting slow-moving personnel inside enclosed structures and behind walls. Using signal multiplexing from two transmitters several receiver positions, it is shown that the virtual array (co-array) implementing MIMO schemes, applied stepped-frequency radars, permit improvement in image resolution of...

Renewable energy is becoming an important way to generate with a much smaller impact on the global environment. Wind power one of most prevalent renewable forms and gaining popularity globally. Offshore wind cables are usually burned deep in sea bottom accurate fault detection localization, very ensure reliability supply, difficult. For this reason, maintenance diagnostic cable systems tasks order reduce cost increase security, quality electricity supplied from offshore generation systems....

Effects of Cauchy integral formula discretization on the concentration time-frequency (TF) distribution are analyzed. As a result this discretization, new forms distributions produced. In order to increase accuracy instantaneous frequency (IF) estimation, two solutions considered: increasing number integration points and multiple successive integrations using same (it corresponds L-form TF distribution). practical applications, fourth-order complex-lag produces very efficient representation....

Time-frequency representations constitute the main tool for analysis of nonstationary signals arising in real-life systems. One most challenging applications time-frequency deal with underwater acoustic signals. Recently, interest dispersive channels increased mainly due to presence wide band nonlinear effect at very low frequencies. That is, if we intend establish an communication link frequencies, dispersion phenomenon has be taken into account. In such conditions, application conventional...

A general form of the time–frequency distribution with complex-lag argument is proposed. It based on generalised distribution, modified to provide an efficient instantaneous frequency estimation in case multicomponent signals. The proposed suitable for numerical realisation and it provides arbitrarily high concentration. theory illustrated by example.

ABSTRACT A measuring technique for antenna gain is presented, based on averaging a normalized transfer function over distance range. Criteria setting the range are drawn by investigating effects of reflection and diffraction. Our method compared to time‐gating two low‐gain, quasi nondirectional antennas. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1553–1557,

This paper proposes an automatic method for extraction of useful information content from time-frequency distributions nonstationary signals heavily corrupted by additive noise. The proposed method, which does not require prior knowledge the signal, initially performs a one-dimensional clustering distribution aimed at segmenting it into fixed number classes. procedure points out basic structural differences noise and signal components (i.e., information) in plane. In fact, presents flat...

The high-order ambiguity function (HAF) was introduced for the estimation of polynomial-phase signals (PPS) embedded in noise. Since HAF is a nonlinear operator, it suffers from noise-masking effects and appearance undesired cross-terms when multicomponents PPS are analyzed. In order to improve performances HAF, multi-lag concept proposed. Based on this approach, several advanced methods (e.g., product (PHAF)) have been recently Nevertheless, these new affected by error propagation effect...

Processing marine-mammal signals for passive oceanic acoustic tomography or species classification and monitoring are problems that have recently attracted attention in scientific literature. For these purposes, it is necessary to use a method which could be able extract the useful information about processed data, knowing underwater environment highly nonstationary. In this context, time-frequency (TF) time-scale methods constitute potential approach. Practically, has been observed majority...

The problem of signal detection, followed by a characterization stage, is considered in this paper. main difficulties arising the detection stage are caused noise, which acts real environment, and multiple time-frequency (TF) structures signal. In paper method based on adaptive grouping TF information provided Gabor filter bank proposed. A Viterbi-type algorithm used as tool for components. results obtained data prove capability proposed approach accurately detect characterize signals with...

The shallow water environment can be considered as a time-dispersive system whose time-varying impulse response expressed superposition of time-frequency components with dispersive characteristics.In this paper, we propose frequency-domain characterization the based on normal-mode model that treats an acoustic medium.After studying characteristics system, blind processing technique is employed to separate without knowledge relevant parameters.This first approximating structure received...

Acoustic channel properties in a shallow water environment with moving source and receiver are difficult to investigate. In fact, when the source-receiver relative position changes, underwater causes multipath Doppler scale changes on transmitted signal over low-to-medium frequencies (300 Hz–20 kHz). This is result of combination multiple paths propagation, motions, as well sea surface motion or column fast changes. paper investigates acoustic (up 150 m depth) conditions using extracted...

A challenging task in over-the-horizon radar (OTHR) is the tracking of target altitude. It has been shown that micro-multipaths due to ocean/ground reflections may reveal important information about elevation maneuvering a target. The Doppler signature such micro-multipath signals typically composed three components having close nonlinear time-frequency behaviors. In this paper, we develop novel analysis techniques for characterization effect signals. proposed method based on local signal...