Stanislav I. Khomenko

Application of Bispectrum Estimation for Time-Frequency Analysis of Ground Surveillance Doppler Radar Echo Signals

A microwave coherent homodyne and polarimetric ground surveillance Doppler radar is employed for collecting the radar returns from moving objects. Nonstationary nonlinearly frequency-modulated and multicomponent backscattered signals are analyzed and described as a sum of Doppler frequency-shifted polynomial chirp-like components. Instantaneous frequencies corresponding to the radiation backscattered by the different parts of a moving spatially distributed object are extracted from the time-varying bimagnitude estimates of transient sample sequences separated from the total received signal by a sliding window and projected into the time-frequency (TF) domain. Experimental investigations demonstrate a clean recovery of evolutionary phase-coupled harmonics for such targets as a swinging metallic sphere or a walking human. The computed TF distributions can be used in radar automatic target recognition systems to retrieve new data for the classification and recognition of ground moving objects.

Time-Frequency Analysis of Radar Backscattered Signals using Phase Coupled Frequencies Extracted from Time-Varying Bispectrum Estimates

A new approach to time-frequency analysis of radar echo responses obtained from moving objects is represented. The suggested approach is based on the extraction of phase-coupled harmonics from time-varying bispectrum estimates of transient sequences separated from the total radar backscattered signal by a sliding window. A coherent, homodyne, and continuous-wave radar has been employed for measuring multi-component, non-stationary, and nonlinear frequency modulated signals backscattered by moving objects. The experimental study underpinned with the theoretical assumptions of the suggested approach has demonstrated clean recovery of time-varying phase-coupled frequencies for test targets like a swinging metallic sphere or a walking human. The obtained time-frequency distributions of phase-coupled harmonics can be recommended as a new information feature in automatic radar target recognition systems.

Using embedded semi-Markov processes for describing nonstationary signals and fields

The possibility of using embedded semi-Markov processes for creating statistical models of signals reflected from the interface (land-sea) as well as from areas of the “clear” sky is considered in the given work. And parameters of these areas are identified on the basis of experimental data. It is shown that the nonstationarity of seasonal changes in the troposphere refractive index can be accounted for by describing its statistics by poly-Gaussian models. Model parameters for each season are derived experimentally. The proposed approach can be used to create a simulation model of the refractive index behavior using embedded semi-Markov processes.

Combined double frequency profiling of microsrtucture rain parameters

The development of double frequency method of radar rain sensing and the results of experimental study of the method are presented. As it was shown the experimental study is in good agreement with calculations and confirms the main conclusions of the theoretical considerations.

Polarization-Spectrum Signatures of Above-Water and Surface Targets

The results of experimental study of backscatter spectral -polarization features from above-water and surface objects are presented. Investigations were carried out with coherent systems both with the pulse and CW modes of millimeter and centimeter wave bands (from 10 sm to 2 mm). The informative features are concerned with modulation both the amplitude and Doppler translation are condition on modulation of scattered signal at the stroke rate for the oared boat and the frequency modulation concerned with hands and lags move of moving man as well are ascertained. For the scattering from the object body the small level of depolarization factor of the scattered signal is typical. Ascertained that for the coincident by frequency spectral components of the signal scattered from the objects on orthogonal polarizations the high values of cross correlation factor is typical.

Doppler radar method for plasma structure investigation

The stratified positive column of glowing discharge plasma was investigated using coherent homodyne measuring transmitter-receiver equipment. The estimation of absolute cross-section of stratified plasma creations was carried out experimentally. Frequency dependencies of a reflected signal from plasma creation have been presented.

Use of double frequency radar for measurement of reflectance-intensity dependence

The results of study of double frequency method of remote sensing of liquid precipitation are presented for measurement of their intensity. Also the calculation algorithm of dependence of radar reflectance vs. rain intensity is described and main results of numerical simulation are discussed.

Seasonal variation of high-altitude profiles of the troposphere refraction coefficient over the land

Results of experimental study of height dependences of the refraction coefficients and their gradients during various seasons are presented.

Diagnosis and Experimental Studies of Coverage Range of Shipborne Centimeter Wave Radars in the World Ocean

On the base of obtained experimental data the method for calculation coverage range of centimeter wave radars is proposed. The method gives a satisfactorily agreement of calculated results with experimental ones.