A Qualitative Study on Microwave Remote Sensing and Challenges Faced in India

Over the past few decades remote sensing has expanded its limits with exponential rise in technology that facilitates accurate data fetching in real time. In view of some of the major problems faced by developing nations, particularly India with its recent advancement in space technology, remote sensing has a vital role to play in resolving many such problems. In the light of recent Global Space Programs where several satellites have been launched for large area mapping using microwave sensors, microwave remote sensing can play a vital role as India experiences a large number of disasters every year. Also, majority of Indian population relies on farming for their livelihood. Microwave remote sensing can have significant effects in both these two scenarios as opposed to its conventional counterpart, optical remote sensing under diverse conditions and facilitate better results in terms of disaster management, prediction and increasing crop yield. The current paper brings out the various details on the work done by using active microwave remote sensing, with specific illustrative examples, for disaster management support, crop management techniques and the challenges associated on carrying out such researches in a diverse terrain like India

Analysis of sandstone pore space fluid saturation and mineralogy variation via application of monostatic K-band frequency modulated continuous wave radar

In this paper we present the preliminary findings from a world first investigation into monostatic frequency modulated continuous wave (FMCW) radar analysis of porous sandstones and their fluid content. FMCW results, within 24 to 25.5 GHz, provide insights into the rock/pore system as well as into mineral and liquid distributions, both crucial for quantitative representation of the fluid-rock system for subsequent assessment of the sandstones. Sandstone samples, here characterised using known techniques of energy dispersive x-ray analysis, gaseous secondary electron and backscattered electron imaging are: Darney, Lazonby Locharbriggs and Red St. Bees sandstones, with FMCW results indicating that, in the K-Band, calculated values for relative permittivity, utilising free-space radiation reflection data, give results that are consistent with the known rock elemental constituents, where each sandstone has different distributions of the dominant quartz and subsidiary other minerals and of grain size and shape distributions. The experimental results support the sensitivity of this sensing modality to variances in rock properties in typical sandstones with complex relative permittivity, ε_r^*, values for unsaturated sandstones ranging from 5.76 to 6.76 and from 12.96 to 48.3 for partially saturated sandstones, with the highest values indicating high permittivity mineral inclusion and/or grain angularity

Laser Based Altimetry for Unmanned Aerial Vehicle Hovering Over a Snow Surface

A microwave radar for non-invasive snow stratigraphy measurements has been developed. Results were promising, but it failed to detect light powder snow in the air-snowpack interface. The aim of this thesis is to find and verify a system for estimating altitude on centimeter scale over a snow surface, independent of snow conditions. Also, relative pitch and roll angle estimation between the UAV and local surface should be resolved, to help directing the radar beam perpendicularly to the surface. After a variety of technical solutions were examined, we propose a system of three time-of-flight near-infrared altimeters pointing at different directions towards the surface. Experimental results showed RMS error of 1.39 cm for range estimation averaged over the most common snow types, and 2.81 cm for wet snow, which was the least reflective medium. An experiment conducted for an array of two altimeters scanning over a snow surface, showed that the local, relative surface tilt was found to be accurate within ±2° given that it was sufficiently planar. Further, the altitude RMS error was estimated to 1.57 cm. We conclude that the chosen altimeter was within the requirements, and that an array of three altimeters would give acceptable relative tilt estimation in to planes on the snow surface. The system should be subject to flight testing and implemented on UAV platform such that it can aid the microwave radar system during snow scanning

Millimeter-Wave Radar Sensor for Snow Height Measurements

International audienceA small and lightweight frequency-modulated continuous-wave (FMCW) radar system is used for the determination of snow height by measuring the distance to the snow surface from a platform. The measurements have been performed at the Centre des Études de la Neige (Col de Porte), which is located near Grenoble in the French Alps. It is shown that the FMCW radar at millimeter-wave frequencies is an extremely promising approach for distance measurements to snow surfaces, e.g., in the mountains or in an Arctic environment. The characteristics of the radar sensor are described in detail. The relevant accuracy to measure the distance to a snow layer is shown at different heights and over an extended time duration. A dedicated laser snow telemeter is used as reference. In addition, the reflection from different types of snow is shown

Frequency synthesizer for integrated FMCW radar sensors in the millimeter-wave band

Primene prenosivih beskontaktnih radarskih senzora kratkog dometa, koji daju informacije o prisustvu, položaju i relativnoj brzini, prakticno su neprebrojive. Ovi radarski sistemi ne samo da imaju potencijal da poboljšaju kvalitet usluga u mnogim oblastima, vec se ocekuje da budu pokretac mnogih inovativnih rešenja ubuduce...Applications of portable short-range noncontact radar sensors, which provide information on presence, position, and relative speed, are virtually countless. These radar systems not only have the potential to improve the service quality in numerous existing fields, but are also expected to be the driving force for many novel applications in the near future..