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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.


Charles Darvin R.,Defence Avionics Research Establishment | Paranjape H.,Defence Avionics Research Establishment | Mohanan S.K.,Defence Avionics Research Establishment | Elango V.,Indian Institute of Technology Madras
IEEE CONECCT 2014 - 2014 IEEE International Conference on Electronics, Computing and Communication Technologies | Year: 2014

The instantaneous frequency estimation of received signal is very important in Electronic Warfare and communication systems, and the performance of radar classification depends on the accuracy of frequency measurements. Hence, different approaches to the instantaneous measurement of the frequency of a radio wave signal are proposed and analysed. The auto-correlation factor based algorithm is optimised to estimate the signal frequency more accurately. The algorithm is also able to estimate the maximum error in the estimated frequency for any input frequency. Simulation results ascertain the robustness of the algorithm and confirm that it is not affected by clock jitter and is capable of detecting pulses from 100 ns width and SNR ≥ 0 dB, over a 4 GHz bandwidth. For SNR ≥ 20 dB, the algorithm is able to estimate 99.4% of the frequencies in the 4 GHz bandwidth within an error of 2 MHz. This algorithm has the potential to be coded and ported on to a Field Programmable Gate Array. © 2014 IEEE.


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.


Raji R.A.,Defence Avionics Research Establishment | Kumar A.P.R.,Defence Avionics Research Establishment | Purohit S.,Defence Avionics Research Establishment | Lakshmi T.,Defence Avionics Research Establishment | And 2 more authors.
Defence Science Journal | Year: 2014

The paper presents advanced mission management system (MMS) for unmanned aerial vehicles, based on integrated modular avionics (IMA) architecture. IMA architecture enables the MMS to host high end functions for autonomous navigation and attack. MMS is a collection of systems to execute the mission objectives. The system constitutes mission computer (MC), sensors and other sub-systems. The MMS-MC needs to execute advanced algorithms like terrain referenced navigation, vision-aided navigation, automatic target recognition, sensor fusion, online path planning, and tactical planning for autonomy and safety. This demands high-end architecture in terms of hardware, software, and communication. The MMS-MC is designed to exploit the benefits of IMA concepts such as open system architecture, hardware and software architecture catering for portability, technology transparency, scalability, system reconfigurability and fault tolerance. This paper investigates on advanced navigation methods for augmenting INS with terrain-referenced navigation and vision-aided navigation during GPS non-availability. This paper also includes approach to implement these methods and simulation results are provided accordingly, and also discusses in a limited way, the approach for implementing online path planning. © 2014 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.


Kulkarni A.S.,Defence Avionics Research Establishment | Vijesh P.,Defence Avionics Research Establishment | Paranjape H.V.,Defence Avionics Research Establishment | Reddy K.M.,Defence Avionics Research Establishment
Defence Science Journal | Year: 2013

This paper compares different digital receiver signal processing schemes as applied to current ESM/RWR systems. The schemes include fast fourier transform (FFT)-based, FIR filter-based and mixed architectures. Use of polyphase FFT and IIR filters is also discussed. The specifications and signal processing requirements of a modern digital electronic warfare (EW) receiver are discussed. The design procedures and architectures for all the schemes are brought out. The tradeoffs involved in selection of different parameters for these schemes are also discussed. The digital receiver schemes are modeled and analyzed for different metrics such as, Parameter measurement accuracies, Pulse handling capability, Frequency separation capability, Number of multipliers required for implementation etc. The analysis is done for a 500 MHz BW digital receiver and assumes 8 bit ADC in the front end. The results obtained for the comparison are discussed in the paper. Limited simulations show that overlapped FFT scheme is a better approach for digital receiver processing. © 2013 DESIDOC.


Singh S.A.,Defence Avionics Research Establishment | Bineesh P.K.,Defence Avionics Research Establishment | Satish Shetty K.,Defence Avionics Research Establishment
Defence Science Journal | Year: 2013

Current and future aircraft systems require real-time embedded software with greater flexibility compared to what was previously available due to the continuous advancements in the technology leading to large and complex systems. Portability of software as one of the aspects of this flexibility is a major concern in application development for avionics domain for fast development and integration of systems. Abstractions of the hardware platform which have been already introduced by the operating system community allow the software modules to be reused on different hardware and with different physical resources. Now operating system community has come up with an abstraction layer called operating system abstraction layer (OSAL) which along with the hardware abstraction unifies the OS architecture too. It provides a common set of primitives independent of the underlying operating system and its particular architecture. Factors such as reliability, scalability and determinism of any application largely depend on the design and architecture of the application. This is the most important and critical factor of real time systems such as mission computers of avionics systems, missile control system or control computers of space shuttle. It demands developer to perform feasibility of different software architecture to select the best alternative. Authors' analysis shows that to make any real time application more secure, scalable, deterministic, and highly portable, OSAL has to be extended to more than just operating system abstraction. This new view of OSAL will be called as system software abstraction layer (SSAL). In this paper, authors attempt to highlight the efficiency of SSAL as well as detailed description of its main features and design considerations. Authors have implemented the SSAL on top of two well known OS (WinCE and Vxworks) and performed extensive evaluations, which shows that it effectively reduces portability efforts while achieving simplicity, predictability, security and determinism. This paper presents in brief, the API functionalities, its components, implementation, interfaces, advantages and overheads along with a case study. © 2013 DESIDOC.


Pitchammal R.,Defence Avionics Research Establishment | Sadda V.,Defence Avionics Research Establishment
Defence Science Journal | Year: 2013

Increasing the complexity of fighter aircraft like modern cockpit environments, covering highly integrated, and complex automatic functions, pose various demands on the crew and adding a heavy workload. Cognitive systems appear to be a promising approach to overcome these deficiencies in future combat aircraft. Developing humancentered automation and designing advanced technology that will capitalize on the relative strengths of humans and machines, are key to the success. This paper presents the approach of applying the artificial intelligence (AI) techniques in the critical mission computer (MC). The mission computer is the central controller of the entire avionics and acts as the front end to the pilot and all other avionic systems by providing all the sensors information, presenting the pilot-vehicle interface and thereby helping a lot in reducing the heavy workload of the pilot. Hence cognitive processing in the MC will make MC to act as an electronic crew assistant sharing the workload of the pilot and helping him in severe situations. Intricate aircraft systems increase the need for intelligent cooperation between pilots and aircraft which will be fulfilled by making the MC as smart or intelligent MC. © 2013 DESIDOC.

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