S. SamadiGorji; B. Zakeri; M.R. Zahabi
Abstract
The aim of this paper is to minimize output phase noise for the pure signal synthesis in the frequency synthesizers. For this purpose, first, an exact mathematical model of phase locked loop (PLL) based frequency synthesizer is described and analyzed. Then, an exact closed-form formula in terms of synthesizer ...
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The aim of this paper is to minimize output phase noise for the pure signal synthesis in the frequency synthesizers. For this purpose, first, an exact mathematical model of phase locked loop (PLL) based frequency synthesizer is described and analyzed. Then, an exact closed-form formula in terms of synthesizer bandwidth and total output phase noise is extracted. Based on this formula, the phase noise diagram as a function of bandwidth is plotted. From the analysis and simulation results, it is observed that the synthesizer has a minimum phase noise at a particular bandwidth.
A. B. Gorji; B. Zakeri
Abstract
Recently, time reversal (TR) method, due to its high functionality in heterogeneous media has been widely employed in microwave imaging (MI) applications. One of the applications turning into a great interest is through-wall microwave imaging (TWMI). In this paper, TR method is applied to detect and ...
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Recently, time reversal (TR) method, due to its high functionality in heterogeneous media has been widely employed in microwave imaging (MI) applications. One of the applications turning into a great interest is through-wall microwave imaging (TWMI). In this paper, TR method is applied to detect and localize a target obscured by a brick wall using a numerically generated data. Regarding this, it is shown that when the signals acquired by a set of receivers are time reversed and backpropagated to the target-embedded media, finding the optimum time frame which the constituted image represents a true location of the target becomes infeasible. Indeed, there are situations pertinent to the target distance ratio that the previously-used Maximum field method and Entropy-based methods may fail to select the optimum time frame. As a result, an improved method which is based on initial reflection from the target is proposed. According to different target locations described in this research, the results show this method prevails over the shortcomings of the former methods.
