The process of increasing the sampling rate of any signal by a factor is known as interpolation. This paper presents the effective and efficient implementation of multistage implementation of digital interpolator using half band filters. The single stage filters are efficient for lower order interpolation factors but for higher rate change which is required in modern digital communication systems like wideband code division multiple access, worldwide interoperability for microwave access single stage implementation does not gives efficient response. For these applications a multistage implementation of the interpolator is preferred. But multistage implementation increases complexity of the overall system. This complexity can be reduced considerably by using half band filters. All this has been done with the help of the Agilent's advanced design software.
In this paper, the performance of single stage and double stage digital interpolators has been compared and has been showed that by using multi stage interpolation system the reliability of any communication system increases drastically. Digital signal interpolation systems can be implemented in a variety of ways. The basic interpolator for up-sampling can be a combination of an expander unit with an interpolation low-pass filter in cascade. Complicated implementations can be done by connecting multiple expander and low-pass filter pairs in cascade. This paper presents the efficient implementation of digital interpolation systems for up-sampling of single stage and double stage digital interpolators by using quadrature phase shift keying technique. Comparison is done in terms of spectrum of generated signal, envelope power, modulated signal trajectory, input and output constellation and noise performance.
The third-order nonlinear optical properties of C_{60}/poly(dimethylacetylendicarboxylate) have been studied using Z-scan technique. Experiments are performed using a CW diode laser at 635 nm wavelength and 26 mW power. The nonlinear absorption coefficient β, nonlinear refractive index n₂, Reχ³, and Imχ³ in C_{60} doped poly(dimethylacetylendicarboxylate) are measured using Z-scan data. Our results show that the values of the nonlinear optical parameters (β, n₂, Reχ³, and Imχ³) of C_{60} doped poly(dimethylacetylendicarboxylate) are smaller than the polymer itself.
Charging operations of a compact Tesla transformer were experimentally investigated, in single-shot and rep-rate (50 pps for 1 s) modes, respectively. The charging limitations were also explored. The experimental results were compared and analyzed. The maximum secondary charging voltages of the Tesla transformer were measured to be 380 kV and 300 kV in single-shot and rep-rate modes, respectively. The RMS pulse-to-pulse instability of the secondary charging voltage is generally less than 10% but increases with the increasing initial voltage across the primary capacitor. Since the secondary capacitor of the Tesla transformer is a pulse forming line (PFL), continued operation is possible if there is breakdown in the PFL. Furthermore, operation can even be continued under occasional breakdown for some pulses, without the effects on the operations of subsequent pulses.
The organic-inorganic hybrid salt: 1,1'-methylenedipyridinium pentacynidonitrosoferrate(II)pentahydrate is synthesized and characterized by multinuclear NMR, IR, and UV-vis spectroscopies and elemental analysis. The third order nonlinear optical properties of the new complex in an aqueous solution have been studied using Z-scan technique. Measurements were performed for input intensities (I₀) of 437 and 241 W/cm² for the two concentrations with a CW diode laser at 635 nm wavelength. The nonlinear optical absorption coefficient (β) and nonlinear refraction (n₂) are found at 1.28×10¯³ cm/W and 10.17×10¯⁹ cm²/W, respectively. The overall results suggested that better nonlinearity was observed at a higher concentration of sample. Our results suggest that this material is considered as a promising candidate for future optical device applications.
Optical limiting performances of acid blue 29 are investigated under irradiation by a 35 mW continuous wave He-Ne laser. The optical limiting behavior is investigated by using transmission measurement through samples with different concentrations. Our results show that the optical limiting efficiency is concentrations dependence. Induced self-diffraction patterns are observed at relatively high intensities starting from 15 mW.
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