It has been well understood that a given signal can be represented in an infinite number of different ways. Of course, different signal representations can be used for different applications. Despite the fact that the number of ways describing a given signal are countless, the most “popular”, important and fundamental variables are: time and frequency. The time domain indicates how a signal’s a...

Underspread and overspread operators are Hilbert–Schmidt operators with strictly bandlimited Kohn–Nirenberg symbols. In this paper, we prove a classical conjecture concerning the necessity of the underspread condition for the identifiability of such operator classes, and, in doing so, we exhibit a new uncertainty principle phenomenon in the time-frequency analysis of operators.

The Segal–Shale–Weil representation associates to a symplectic transformation of the Heisenberg group an intertwining operator, called metaplectic operator. We develop an explicit construction of metaplectic operators for the Heisenberg group H(G) of a finite abelian group G, an important setting in finite time-frequency analysis. Our approach also yields a simple construction for the multivari...

We investigate the properties an exotic symbol class of pseudodifferential operators, Sjöstrand’s class, with methods of time-frequency analysis (phase space analysis). Compared to the classical treatment, the time-frequency approach leads to striklingly simple proofs of Sjöstrand’s fundamental results and to far-reaching generalizations.

A polarimetric coherent Time-Frequency (TF) decomposition approach for ship detection is proposed in this paper. At first, the PolSAR data are decomposed in azimuth direction, range direction only or in both directions. Then a novel statistical descriptor called polarimetric TF coherence indicator, is applied to detect maritime targets in different environments. By using polarimetric RadarSat2 ...

Moving targets within SAR scenes are distorted depending on the particulars of the target motion. For small motions, the uncompensated phase of a point reflector is a sum of a term proportional to the range component of the target motion, and a more complicated term depending on the azimuth motion. The resulting phase may be analysed with time-frequency techniques since the motion effect may al...

We present a new technique for estimating speed and slip of the induction motor. The method is based on the time-frequency analysis of the current supplying the motor. Interpolated DFT, computed in the sliding time window, is used for obtaining current spectrograms with high frequency resolution. The speed and the slip are estimated from the fluctuation of amplitude of the main current harmonic...

Condition monitoring (CM) is an essential technique used for monitoring various systems and system components and is supplemented with other techniques, such as video monitoring. Due to the fact that the acceleration signal is suitable for acquisition and is of non-stationary nature, CM is used to monitor various parameters of a monitored system. In order to process the acquired vibration signa...