T. Ganesh ¹, S. Rajesh ², Francis P. Xavier ³

Affiliations
1 PG & Research Department of Physics, Presidency College, Chennai-600 005, IN
2 PG & Research Department of Physics, A.M Jain College, Chennai- 600 114, IN
3 LIFE, Loyola College and Loyola-ICAM College of Engineering and Technology (LICET), Chennai-600 034, IN

Abstract

Aluminium doped zinc oxide (Zn_1-xAl_xO) thin films were deposited by sol-gel spin coating technique onto a glass substrate (x=0-5wt%). The films were characterized by UV-Visible spectroscopy, SEM and were subjected to photoconductivity, temperature dependant conductivity and photo response measurements. The film with Al-1.5wt% showed the maximum absorption in UV and had a good optical transmission (~75%) in the visible regions respectively. The SEM images showed crack free films with little grain boundaries with decrease in grain size at higher aluminium concentration. The photoconductivity measurements reveal that there is a phenomenal increase in the photocurrent upon doping compared to undoped ZnO. The photocurrent reaches its maximum value (25μA) at 10V which is nearly 50 times more than the dark current (0.44μA) for Al-1.5wt% doped ZnO. The photocurrent then decreases for further increase in Al concentration. The photoresponse study gives the measure of rise and decay time. The rise time was found to be shorter for Al-1.5wt% among the doped film but longer than undoped ZnO. The temperature dependant conductivity shows that the thermal activation energy for the film decreases at Al-1.5wt% aluminium concentration and then increases for other concentrations in the temperature range 300-400K. The optimum conditions for maximum photoconductivity and photoresponse have been studied for photoconductive applications and the results presented.

Keywords

Sol-gel, Spin Coating, Photoconductivity, Activation Energy

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K. Bavitra ¹, S. Sinthuja ², N. Manoharan ³, S. Rajesh ⁴

Affiliations
1 EEE, AMET University, Kanathur, Chennai, 603112, IN
2 TEJAS Research Centre of Excellence, AMET University, Chennai, 603112, IN
3 AMET University, Chennai, 603112, IN
4 Department of ECE, Bharath University, Chennai, IN

Abstract

The recent trend in photovoltaic inverter is to use topologies with the absence of transformers to acquire higher efficiency. This gives very low ground leakage current. After the elimination of transformer in a grid/Load connected Photovoltaic (PV) system, a galvanic connection exists between the grid/Load and the PV array. The different inverter topology that generates no varying common-mode voltage is proposed to avoid leakage currents, this proposes a new topology with six switches and two diodes that generates no varying common-mode voltage and exhibits high efficiency

Keywords

Ground Leakage Current, H-Bridge, Photovoltaic Inverter, Transformer Less Topology

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S. Mariappan ¹, G. Sasibhusana Rao ¹, Swarna Ravindrababu ², S. Sinthuja ³, S. Rajesh ⁴

Affiliations
1 Department of Electronics and Communication, AU College of Engineering, Visakhapatnam - 530003, Andhra Pradesh, IN
2 Samsung India, Bangalore – 560037, Karnataka, IN
3 Department of Tejas Research Centre of Excellence, AMET University, Chennai - 603112, Tamil Nadu, IN
4 Department of Electronics and Communication Engineering, Bharath University, Chennai - 600020, Tamil Nadu, IN

Abstract

The acquisition of GNSS signal is the most challenging part of any GNSS receiver. With the modernized GNSS system having longer code length and wider bandwidth, the size of the data block becomes large. To reduce the computational load of the processor, the reduction in the size of the data block without compromise in the acquisition loop performance provides overall improvement to the system. Here, a model is developed for acquisition of GPS signal L1 and L2C by compressing the input raw GPS signal with sequences of perfect periodic autocorrelation properties such as the Ipatov sequence. A compression matrix of the required dimension is constructed for compressing the input GPS signal. The improvement in the acquisition performance of the model is discussed.

Keywords

Acquisition, Compression, GPS, L2C, Modernised GPS

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