Airborne GNSS Reflectometry for Water Body Detection

This article is dedicated to the study of airborne GNSS-R signal processing techniques for water body detection and edge localization using a low-altitude airborne carrier with high rate reflectivity measurements. A GNSS-R setup on-board a carrier with reduced size and weight was developed for this application. We develop a radar technique for automatic GNSS signal segmentation in order to differentiate in-land water body surfaces based on the reflectivity measurements associated to different areas of reflection. Such measurements are derived from the GNSS signal amplitudes. We adapt a transitional model to characterize the changes in the measurements of the reflected GNSS signals from one area to another. We propose an on-line/off-line change detection algorithm for GNSS signal segmentation. A real flight experimentation took place in the context of this work obtaining reflections from different surfaces and landforms. We show, using the airborne GNSS measurements obtained, that the proposed radar technique detects in-land water body surfaces along the flight trajectory with high temporal (50 Hz ) and spatial resolution (order of 10 to 100 m2). We also show that we can localize the edges of the detected water body surfaces at meter accuracy.

Sector wise echoes study and climatology around Jaisalmer

The capability of Weather Radar to see through the thunder clouds and rain has made it a unique observation tool for remotely surveying the atmosphere. Pulsed radar technique has been applied with remarkable success to map the rain field of various duration and intensities along with movement of storms in real time within the effective detection range of radar. It is a very good tool for forecaster to provide better warning for impending storms and heavy rainfall over the area under radar surveillance and thereby losses due to storm can be minimized while their benefits can be continued like water resource management. In the present work attention has been focused on conducting a comprehensive study of frequencies of occurrence of echoes around Jaisalmer up to 200 km from radar site and the surrounding of it has divided into four equal sectors, i.e., sector-1 (NW, 270°-360° ) , sector-2 (NE, 0°-90°) , sector-3 (SE, 90°-180° ) and sector-4 (SW, 180°-270°). Total number of echoes under the study was 28918 for the period from 19th April, 1993 to 31st December, 2010. Total number of echoes analyzed in Sector-1, were 5441(18.8%), in sector-2, number of echoes analyzed were 9554(33.0%), in sector-3, number of echoes analyzed were 9479 (32.8%) and in sector-4, number of echoes analyzed were 4444(15.4%). Radar echoes to be classified month-wise and the lowest number of average echoes observed in the month of December was 0.4%, in the month of November 0.5%, in October and March 1.6% and in the month of January and February 2.0% .The highest number of annual average echoes observed in the month of July was 30.1% followed by August 24.6%, June 17.2%, May 8.3%, April 6.3% and September 5.8%. Height wise echoes analyzed and the highest number of echoes found for 3 km in all the four sectors were 29.0% and the lowest were for 16 km as 0.2%.

Transportation Among Returning Citizens: “You Just Want to Stay Down and Get High”

The United States is releasing more individuals from prisons than ever before. However, returning citizens face numerous challenges transitioning back into community life and many communities remain ill-equipped in successfully supporting them. This study focuses on transportation as in integral component to the success of returning citizens. Rapid and rigorous qualitative data analysis (RADaR technique) is applied to interviews ( n = 15) with individuals having returned to their community about the impact of transportation on their reentry. Analysis resulted in three primary themes; interviewees reinforced existing knowledge of the issues with transportation disadvantage, transportation is an extension of freedom, and transportation is directly connected to reentry success. These findings suggest a tiered structure of transportation freedom for returning citizens. This model of transportation will aid future researchers and policymakers in considering how to better resource returning citizens to maximize their success.

A study of microwave over-sea propagation with high-potential x-band doppler radar

Subject and Purpose. The paper is devoted to the microwave propagation over the sea in the nearshore region. Emphasis is on microwave attenuation measurements in the semi-shade and deep-shade areas with a view to study conditions of the microwave propagation on a beyond-the-horizon path in the nearshore area using a radar method. Methods and Methodology. A radar technique, developed and tested, provides measuring a microwave attenuation coefficient along a 60 km long beyond-the-horizon path in the tropospheric surface layer. High-grade radar and Doppler radar beacons (racons) are employed. Of interest are experimentally obtained temporal dependences of signals from racons situated at different heights and, also, spatial field distribution curves from a steadily moving racon running a height 1 to 27 m for 25 minutes. Results. A prototype of high-grade X-band coherent continuous-wave (Doppler) radar has been designed and fabricated. A radar technique has been developed and tested for the analysis of microwave beyond-the-horizon propagation conditions in the shadow region, which involves continuous-wave (Doppler) radar and Doppler racons with a radar cross section (RCS) of about 60 m2. Conclusions. The technique proposed enables reliable tracking of racon responses up to a double radiohorizon range on over-sea paths. This technique can be used for radar calibrations when dealing with various location problems in the nearshore area, including detection and tracking small-size and low-flying targets and their radar identification.