Faculty Publications
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Item A New Kaiser-Bessel Constant Modulus Technique for Smart Antenna Beamforming(Springer Science and Business Media Deutschland GmbH, 2022) Shashidhara, K.S.; Dakulagi, V.; Kaur, J.; Yeap, K.H.; Singh, M.; Ratnesh, R.K.In this work, an improved constant modulus algorithm (CMA) blind beamformer exploiting the Kaiser-Bessel window which is dubbed as ‘KB-CMA’ for the smart antenna system is presented. In array signal processing, especially in beamforming technology, the CMA is one of the most popular methods due to its low complexity. However, this beamformer has a very slow convergence time and has a large side lobe level (SLL). This hinders the utility of the CMA method in dynamic circumstances where the speedy capture of the user signal is required. Also, this method is not suitable in the wireless applications where conditions of the channel are speedily varying. To circumvent this problem and to make the classical CMA suitable for practical applications, we propose an improved CMA. The major advantage of the new method is that its time of convergence is almost several times quicker than the classical CMA. Furthermore, we exploit the Kaiser-Bessel window to suppress the SLLs of the improved CMA. Experimental results demonstrate that the proposed method has fast convergence time and the reduced SLL. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Efficient Coherent Direction-of-Arrival Estimation and Realization Using Digital Signal Processor(Institute of Electrical and Electronics Engineers Inc., 2020) Dakulagi, V.; Alagirisamy, M.; Singh, M.A novel efficient coherent direction-of-arrival (DOA) estimation method is devised in this article. First, a new cost function without the knowledge of source number is developed exploiting the Toeplitz matrices' joint diagonalization structure. Then, the revised steering vectors are used in the place of projection weights of the steering vectors to reconstruct the power spectrum in both noise and signal subspaces. The coherent DOAs are estimated using the 1-D search. Furthermore, the computational complexity of the proposed method is significantly reduced using the Nystrom approximation. Finally, the developed theoretical model is implemented on the TMS320C6678 digital signal processor (DSP) to exemplify the efficacy of the novel method. © 1963-2012 IEEE.Item Reactive magnetron sputtered–assisted deposition of nanocomposite thin films with tuneable magnetic, electrical and interfacial properties(Springer Science and Business Media B.V. editorial@springerplus.com, 2020) Ratnesh, R.K.; Singh, M.; Pathak, S.; Dakulagi, V.In this work, different magnetic thin films of Ni, NiFe and NiFe2O4 are deposited on the SiO2 substrate using sputtering technique. Our experiments confirmed that thin films possess a good nanocrystalline structure. The key deposition parameters controlling their magnetic properties are sheet resistivity, crystalline structure and microtopography of the sputtered thin film. Besides, the reactive gas oxygen (O2) also plays a leading role in transforming the phase and structure of the ferrite film. The nanocrystalline nature of the ferrite film results in the reduction of overall coercivity (HC). The thickness of the sputtered thin film is in the range of 800–1000 Å. The prepared film exhibits roughness in the range of (~ 0.60 to ~ 0.98 nm). Furthermore, the structural transformation study is performed with X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The quite low roughness, high resistivity and low Hc make NiFe2O4 thin film as a potential candidate for the future spintronics, optoelectronics, photocatalysis and solar cell applications. © 2020, Springer Nature B.V.