Topic
Time–frequency analysis
About: Time–frequency analysis is a research topic. Over the lifetime, 5407 publications have been published within this topic receiving 104346 citations.
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TL;DR: A new method is introduced for interference excision in spread-spectrum communications that is conducive to software-radio applications and a significant improvement in receiver performance/bit-error rates is achieved over the case where no projection is performed.
Abstract: A new method is introduced for interference excision in spread-spectrum communications that is conducive to software-radio applications. Spare processing capacity in the receiver permits the use of time-frequency techniques to synthesize a nonstationary interference from the time-frequency domain using least squares methods. The synthesized signal is then subtracted from the incoming data in the time domain, leading to jammer removal and increased signal-to-interference-and-noise ratio at the input of the correlator. The paper focuses on jammers with constant modulus that are uniquely described by their instantaneous frequency characteristics. With this a priori knowledge, the jammer signal amplitude is restored by projecting each sample of the synthesized signal to a circle representing its constant modulus. With the phase matching provided by the least squares synthesis method and amplitude matching underlying the projection operation, a significant improvement in receiver performance/bit-error rates is achieved over the case where no projection is performed. Software-radio aspects including computational complexity and processing modes are also discussed.
34 citations
TL;DR: In this article, a version of Heisenberg's uncertainty inequality for the windowed Hankel transform is shown to hold for sets of f-dimensional sets of variables. But this inequality is not applicable to the case of sets of F-dimensional variables.
Abstract: The aim of this paper is to prove a version of Heisenberg's uncertainty inequality for the windowed Hankel transform. As a side results, we extend some others uncertainty principles about sets of f...
34 citations
TL;DR: A novel measurement method based on null space pursuit and S transform is presented to detect the faults of the bearing vibration signal and several real vibration signals containing bearing fault signature are investigated to verify the effectiveness.
34 citations
TL;DR: An adaptive IF estimator with the time-varying and data-driven window length and distribution order is developed and lower order time-frequency distributions are introduced.
Abstract: The L-Wigner distributions are defined in order to improve the concentration of signal's time-frequency representation. For a finite distribution order and nonlinear instantaneous frequency (IF) it gives biased IF estimates. In the case of noisy signals the optimal window length and distribution order depend on the noise variance and unknown IF. In this article an adaptive IF estimator with the time-varying and data-driven window length and distribution order is developed. Based on the analysis that has been done here, lower order time-frequency distributions are introduced.
34 citations
TL;DR: This contribution extends the reassignment method (RM) and synchrosqueezing transform (SST) to arbitrary time-frequency localized filters and, in the first case, arbitrary decimation factors and proposes a processing scheme that benefits both from the improved localization of the reassigned representation and the frame properties of the underlying complex-valued representation.
34 citations