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1
Content available remote Wigner-Ville distribution and ambiguity function associated with the quaternion offset linear canonical transform
Bhat Mohammad Younus, Almanjahie Ibrahim M., Dar Aamir H., Dar Javid G.
Demonstratio Mathematica
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2022
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Vol. 55, nr 1
786--797
EN
Wigner-Ville transform or Wigner-Ville distribution (WVD) associated with quaternion offset linear canonical transform (QOLCT) was proposed by Bhat and Dar. This work is devoted to the development of the theory proposed by them, which is an emerging tool in the scenario of signal processing. The main contribution of this work is to introduce WVD and ambiguity function (AF) associated with the QOLCT (WVD-QOLCT/AF-QOLCT). First, the definition of the WVD-QOLCT is proposed, and then several important properties such as dilation, nonlinearity, and boundedness are derived. Second, we derived the AF for the proposed transform. A bunch of important properties, including the reconstruction formula associated with the AF, are studied.
2
Analiza sygnałów niskiej częstotliwości do zastosowań sodarowych
Knioła M., Rogala T.
Elektronika : konstrukcje, technologie, zastosowania
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2018
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Vol. 59, nr 8
33--37
PL
Wysoka rozróżnialność w odległości i częstotliwości stanowią istotny problem zarówno w aplikacjach radarowych (RADAR, ang. Radio Detection and Ranging), jak i sodarowych (SODAR, ang. Sound Detection and Ranging). Pomimo wielu wspólnych cech systemów radarowych i sodarowych, duża różnica w zakresie częstotliwości pracy wymusza dokładną analizę emitowanych sygnałów sondujących. W artykule przedstawiono wyniki badań mających na celu określenie parametrów sygnałów złożonych odpowiedzialnych za uzyskanie odpowiedniej rozdzielczości zasięgu oraz częstotliwości przy użyciu sygnałów o niskiej częstotliwości dla aplikacji sodarowych.
EN
High range and Doppler resolution is a significant issue in both RADAR (Radio Detection and Ranging) and SODAR (Sound Detection and Ranging) applications. Despite the many common features of the RADAR and SODAR systems, a very large difference in the frequency of the signal forces a thorough analysis of the emitted probing signals. This article presents the results of research aimed at determining parameters of complex waveforms responsible for obtaining suitable range/Doppler resolution using low frequency signals for SODAR applications.
3
Content available Construction of waveform library in cognitive radar
Guo Y., Wu Y., Liu H.
Polish Maritime Research
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2017
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S 2
22--29
EN
Based on the thoughts of cognitive radar, Fractional Fourier Transform (FrFT) is used to generate a rotatable waveform libraries of Frank coded/Barker coded waveform in this paper. Then, the ambiguity function is used to analyze the delay resolution, Doppler resolution, delay side-lobe level, and Doppler side-lobe level of the waveform libraries and orthogonality of them is also analyzed. Furthermore, we proved theoretically that there is a fixed coordinate transformation between the waveforms of library and its origin waveform. Therefore, the Cramér-Rao low bound (CRLB) of motion parameters can be computed easily using the waveforms of the libraries, which facilitate the subsequent waveform scheduled work. Simulation results show that the library waveforms can reduce delay resolution to satisfy the different situations and can bring significant benefits for delay resolution, orthogonality and reuse interval.
4
Content available Single-epoch precise positioning using Modified Ambiguity Function Approach
Cellmer S.
Technical Sciences / University of Warmia and Mazury in Olsztyn
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2013
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nr 16(4)
265--280
EN
Single-epoch positioning is a great challenge in recent research related to GNSS data processing. The Modified Ambiguity Function Approach (MAFA) method can be applied to perform this task. This method does not contain a stage of ambiguity resolution. However the final results take into account their integer nature. The functional model of the adjustment problem contains the conditions ensuring the integer nature of the ambiguities. A prerequisite for obtaining the correct solution is a mechanism ensuring appropriate convergence of the computational process. One of such mechanisms is a cascade adjustment, applying the linear combinations of the L1 and L2 signals with the integer coefficients and various wavelengths. Another method of increasing the efficiency of the MAFA method is based on the application of the integer de-correlation matrix to transform observation equations into equivalent, but better conditioned, observation equations. The next technique of improving the MAFA method is search procedure. This technique together with the de-correlation procedure allows to reduce the number of stages of the cascade adjustment and to obtain correct solution even in the case when a priori position is a few meters away from the actual position. This paper presents some problems related to search procedure. The results of single-epoch positioning using improved MAFA method are presented.
5
Content available remote Analiza funkcji nieoznaczoności dla wybranych sygnałów w zastosowaniu do radarów pasywnych
Walenczykowska M., Kawalec A.
Przegląd Elektrotechniczny
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2011
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R. 87, nr 10
174-176
PL
W artykule omówiono możliwości wykorzystania sygnałów nadajników okazjonalnych w radarze pasywnym, w szczególności sygnały stacji FM. Przedstawiono kształt funkcji nieoznaczoności tych sygnałów oraz zobrazowano wpływ parametrów sygnału oraz odbiornika na możliwości detekcyjne radaru.
EN
The article investigates possibility of using waveforms of transmitters of opportunity for passive radars, especially FM signals. This report shows shape of ambiguity functions and impact of receiver and waveform parameters on passive radar detection abilities.
6
Content available remote Using the integer decorrelation procedure to increase of the efficiency of the MAFA method
Cellmer S.
Artificial Satellites : Journal of Planetary Geodesy
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2011
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Vol. 46, No. 3
103--110
EN
The Modified Ambiguity Function Approach (MAFA) is a method of GNSS carrier phase processing. In this method, the functional model of the adjustment problem contains the conditions ensuring the "integerness" of the ambiguities. These conditions are expressed in the form of differentiable function. A prerequisite for obtaining the correct solution is a mechanism ensuring not only the "integerness" of the ambiguity but also appropriate localization of the search space in the place where the ambiguities have correct values. One of such mechanisms is cascade adjustment, applying the linear combinations of the signals L1 and L2 with the integer coefficients and various wavelengths. This paper presents another, independent from the previous, approach to increase the efficiency of the MAFA method. It is based on the application of the integer decorrelation matrix to transform observation equations into equivalent, but better conditioned, observation equations. The transformation matrix is obtained in the well-known ambiguity variance-covariance matrix integer decorrelation process.
7
Funkcja niejednoznaczności sygnałów losowych
Meller M.
Prace Przemysłowego Instytutu Telekomunikacji
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2009
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Vol. 59, z. 143
3-12
PL
Rozważono funkcję niejednoznaczności szerokopasmowego sygnału szumowego. Skupiono się na konsekwencjach przypadkowości rozważanej klasy sygnałów. Opisu właściwości funkcji niejednoznaczności dokonano przez analizę jej momentów pierwszego i drugiego rzędu. Wyniki analizy teoretycznej uzupełniono przykładami symulacyjnymi.
EN
An ambiguity function of wideband random noise signals is considered. The paper focuses on the consequences of signal randomness. Properties of the ambiguity function are described using its moments of first and second order. Theoretical results are supported with simulations.
8
Content available On the ambiguity function for accelerating target in FMCW radar
Rytel-Andrianik R.
Journal of Telecommunications and Information Technology
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2007
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nr 1
40-44
EN
In the paper, we are concerned with FMCWradar detection of an accelerating target, echo of which is buried in an additive white Gaussian noise. We derive and analyze three-dimensional generalized ambiguity function for target range, velocity and acceleration. We interpret known properties of this function and obtain new ones, which allows us to specify resolutions and regions of unambiguity for range, velocity and acceleration. The obtained resolutions we express in terms of corresponding Cramer-Rao bounds.
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