Time reversal mirror (TRM) is a principle by which the physical channel can be exploited to perform in-situ equalization and thereby counter channel dispersion. TRM-based signaling can be used to spatially and temporally achieve a sharp signal focus, thereby significantly enhancing signal to noise ratio. TRM signaling can find application in sonar detection as well as communication underwater. In the course of the project, a simulation environment for propagation, signaling and detection for sonars was developed in Matlab. We also constructed a tank-facility for underwater experiments supporting the project. In this NRB sponsored project, we successfully demonstrated the principle of time-reversal mirror in sonar signaling experimentally in an Underwater Tank Facility. Rs. 2.5 Million funded from NRB [2009-2013].
Underwater acoustic communication is severely limited in bandwidth and multipath distortion in addition to reverberation. TRM signaling with multicarrier OFDM modulation is proposed here to alleviate problems of dispersion and noise in underwater communication. In this project, we explore the use of multicarrier modulation for acoustic communication in underwater channels. A mathematical signal model of underwater acoustic communication using multicarrier modulation (OFDM) and time-reversal mirror in shallow-ocean was developed. Through careful analysis, we also designed a framework for comparison of OFDM and TRM-based underwater acoustic communication methods so as to recommend suitable regimes of operation for each mode of communication (OFDM and TRM). In the course of the project, we developed algorithms for simulation of propagation and communication in underwater channels. We also tested several features in underwater experiments. Rs.1.0 Million funded from VTU. [2011- 2014].
Concentrated solar power (CSP) is a serious contender for tapping solar energy, and avoids huge outlays required for manufacture of typical solar-PV systems. It is possible to use reflector arrays with simple mirrors to build sun-synchronous heliostats, which upon focusing sunlight can achieve very high temperatures. These could be used for industrial heating or for driving a Stirling Engine to produce energy. A working solar-tracker has been developed by us in this project with wireless control for a CSP solar farm. These are readily usable for heating and drying such as in food-processing. We would like to test them next in a farm configuration with a Stirling Engine or equivalent heat engine. PES funded the project [2012-14].
The backdrop for this project was the IRNSS system for regional navigation planned by ISRO. The project goal was to design an efficient CDMA code-set that has the most desirable autocorrelation and cross-correlation properties to be used across various satellites. Conducting interference studies to study the effect of spurious radiation and its effect on signal acquisition for IRNSS (especially in the 2.4GHz ISM band) was another major objective. As part of the project, a link-level simulator to demodulate, detect and decode the satellite transmissions for radio-location with minimal acquisition time and low enough C/I levels was developed. A set of CDMA codes were designed and delivered for use in civilian or military navigation using satellites for IRNSS system. Rs.1.5 Million funded by ISRO [2011-13].
