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Binu S.,Kerala University | Kochunarayanan K.,Kerala University | Mahadevan Pillai V.P.,Kerala University | Chandrasekaran N.,Defence Avionics Research Establishment
Microwave and Optical Technology Letters | Year: 2010

This article reports the principle of operation, design aspects, experimentation, and performance of a noncontact fiber optic liquid level sensor. The sensor is based on the phenomenon of reflective concept. The device consists of fiber optic transmitter, fiber optic probe, floating reflector, photodiode detector, and digital multimeter. The fiber optic probe consists of two 60-cm-long PMMA (polymethyl methacrylate) fibers of diameter 1 mm, numerical aperture 0.5, core refractive index 1.492, and cladding refractive index 1.402. The fiber optic sensor is a promising alternative to other well-established methods for the measurement of liquid level due to its simplicity of design, high precision, long-term stability, linearity, high degree of sensitivity, dynamic range, noncontact sensing, and low cost of the fabrication make it suitable for applications in precise level control in analytical and process chemistry, biochemistry, bioanalytics, and on-line measurement or inspection of liquid level. © 2010 Wiley Periodicals.


Binu S.,Indian Institute of Technology Delhi | Chandrasekaran N.,Defence Avionics Research Establishment
Optoelectronics and Advanced Materials, Rapid Communications | Year: 2010

This paper reports the principle of operation, design aspects, experimentation and performance of an extrinsic PMMA (polymethyl methacrylate) fibre optic probe for the measurement of micro displacement. The device consists of fibre optic transmitter, fibre optic probe, reflective surface, photodiode detector and digital multimeter. The fibre optic probe consists of three 80 cm long PMMA (polymethyl methacrylate) fibres of diameter 1mm, numerical aperture 0.5, core refractive index 1.492 and cladding refractive index 1.402. The sensor can work in either the positive slope region or the negative slope region. The sensor is capable of measuring displacement ranging from 0.1 to 0.8mm with sensitivity of 3.002 V/mm in the positive slope region and 1.4 to 2.6 mm in the negative slope region with a sensitivity of -1.031V/mm. The fibre optic sensor is a promising alternative to other well-established methods for the measurement of displacement due to its simplicity of design, high precision, long term stability, linearity, high degree of sensitivity, dynamic range, non-contact sensing and low cost of the fabrication make it suitable for applications in industries for position control, measurement in the hazardous regions and on-line measurement or inspection of test components.


Rao M.S.,Defence Avionics Research Establishment | Mishra C.C.,Indian Defence Institute of Advanced Technology | Naik K.K.,Indian Defence Institute of Advanced Technology | Reddy K.M.,Defence Avionics Research Establishment
Defence Science Journal | Year: 2015

Electronic warfare receiver works in the wide electromagnetic spectrum in dense radar signal environment. Current trends in radar systems are ultra wideband and low probability of intercept radar technology. Detection of signals from various radar stations is a concern. Performance and probability of intercept are mainly dependent on high speed ADC technology. The sampling and reconstruction functions have to be optimized to capture incoming signals at the receiver to extract characteristics of the radar signal. The compressive sampling of the input signal with orthonormal base vectors, projecting the basis in the union of subspaces and recovery through convex optimisation techniques is the current traditional approach. Modern trends in signal processing suggest the random modulator pre-integrator (RMPI), which sample the input signal at information rate non-adaptively and recovery by the processing of discrete and finite vectors. Analysis of RMPI theory, application to EW receiver, simulation and recovery of EW receiver signals are discussed. © 2015, DESIDOC.


Vanitha D.,Defence Avionics Research Establishment | Kundhavai R.M.,Defence Avionics Research Establishment
Defence Science Journal | Year: 2013

This paper presents a holistic solution to the navigation requirements in a time critical electronic warfare systems like missile warning systems (MWS). In a passive MWS using IR sensors the efficiency of the system is determined by attributes such as low false alarm rate, minimal response time and ability to track different IR radiating objects by association and correlation of consecutive detections through time. Such a system is required to be supported by a navigation system capable of accurate estimation of the aircraft position, attitude angles and altitude. In this paper, estimation techniques used to accurately calculate aircraft navigation data at the time of capture of IR frames are discussed. The paper discusses about synchronization of INGPS, IR sensors &Processor on to same timeline. The paper also intends to evaluate the performance of wavelet transform filter in effective elimination of noise in navigation parameters like acceleration and attitude angle rates for a better estimation of position and attitude. © 2013 DESIDOC.


Pitchammal R.,Defence Avionics Research Establishment | Sarala S.,Defence Avionics Research Establishment
Defence Science Journal | Year: 2013

Mastering increasing complexity of electronic warfare (EW) airborne equipment systems needs new architectural concepts mainly based on modular design, generic resources and reliable communication buses. Less is more architectural concept replaces separate EW line replaceable units with fewer centralized processing units. This approach leads to a robust architecture for the next generation EW suite development in a unified fashion and thereby promising significant weight reduction and maintenance savings. In general, this approach is represented by a blanket term called integrated modular avionics (IMA). IMA architecture based EW suite development concentrates with the main goals of IMA such as technology transparency, resource sharing, incremental qualification, reduced maintenance cost, and so on. © 2013 DESIDOC.

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