Length frequency data of the longtail tuna, Thunnus tonggol collected from October 2006 to September 2007 were analyzed for evaluation of the stock parameters. T. tonggol is mainly caught by gillnet method. Yearly tuna and tuna-like catches in Iran are of the order of 174,234 mt, close to 46% of which are longtail tuna. The VBG parameters for longtail tuna were: L∞ =133.72cm K=0.35 year−1.The l...

Frequency discriminators are widely used in electronic warfare systems for the instantaneous frequency measurement of intercepted signals, allowing rapid identification of threat emitters. This paper reviews microwave discriminator architectures based on multiple delay line, phase measurement with parallel digital processing, for operation over decade bandwidths. An alternative reflection mode ...

In this paper, we propose a method –based on the discrete evolutionary transform (DET)– to estimate the instantaneous frequency of a signal embedded in noise or noise-like signals. The DET provides a representation for non-stationary signals and a time-frequency kernel that permit us to obtain the time-dependent spectrum of the signal. We will show the instantaneous phase and the corresponding ...

In time-frequency analysis Hilbert transformation is used to define analytic signals based on which meaningful instantaneous amplitude and instantaneous frequency are defined. In relation to this background we study characteristic properties of the real-valued measurable functions ρ(t) and θ(t), t ∈ R, such that H(ρ(·) cos θ(·))(t) = ρ(t) sin θ(t), ρ(t) ≥ 0, where H is the Hilbert transformatio...

Orthogonal frequency division multiplexing (OFDM) is considered in this paper from the perspective of usage in imaging radar scenarios with deception jamming. OFDM radar signals are inherently multifrequency waveforms, composed of a number of subbands which are orthogonal to each other. While being employed extensively in communications, OFDM has not found comparatively wide use in radar, and, ...

In this paper, we propose a novel time-frequency distribution (TFD) for the analysis of multi-component signals. In particular, we use synthetic as well as real-life speech signals to prove the superiority of the proposed TFD in comparison to some existing ones. In the comparison, we consider the cross-terms suppression and the high energy concentration of the signal around its instantaneous fr...

In this paper, the concept of instantaneous parameters, which has previously been associated exclusively with 1-D measures like the instantaneous frequency and the group delay, are extended to the 2-D time-frequency plane. Such generalized instantaneous parameters are associated with the shorttime Fourier transform. They may also be interpreted as local moments of certain time-frequency distrib...

Stochastic calculus methods are used to estimate the instantaneous frequency of a signal. The frequency is modeled as a polynomial in time. It is assumed that the phase has a Brownian-motion component. Using stochastic calculus, one is able to develop a stochastic differential equation that relates the observations to instantaneous frequency. Pseudo-maximum likelihood estimates are obtained thr...

In the past, when patients were taking computed tomography (CT) scan, the physician usually monitored the patients on-site as a passive way; however, the entire physiological conditions of the patients couldn’t be fully comprehended this way. According to many clinical reports, the heart rates of the patients under tomography may fluctuate because of the injection of contrast medium. A standard...