The significance of airborne radiometric and airborne magnetic (AM) surveys in prospecting for atomic minerals was recognised by AMD as early as 1955 when the survey was undertaken by hiring a Dakota aircraft with indigenously designed and fabricated Total Count system on board. In 1972 the total count system was replaced with in-house designed high sensitivity Airborne Gamma Ray Spectrometer and Proton Precession Magnetometer fitted on the hired Dakota aircraft.
The continuous hardware upgradation and refinement of the data acquisition, processing and interpretation capabilities resulted in the development of high sensitivity Notebook PC-based gamma ray spectrometer with larger NaI (Tl) detector crystals. From 1997 till 2002, this unit, interfaced with Cs-vapour magnetometer and Global Positioning System, was flown by hiring Beechcraft B-200 aircraft of National Remote Sensing Agency. The Flight line interval ranged from 500 to 2000 meters.
In 2003 heliborne EM survey was carried out by outsourcing the operation to NGRI (National Geophysical Research Institute) with their instruments. The flight line interval was 250 meters.
Calibration pads as per IAEA standards were constructed, at Nagpur airport for calibration of spectrometer and calculation of system sensitivities and stripping ratios. This is the only facility in the entire southeast Asia. Two test strips of natural terrain, located at Devarkonda, Nalgonda dist, Andhra Pradesh and at Malharbodi, Bhandara dist., Maharashtra, were identified. These are being used for the determination of height attenuation coefficients for each of the radioelements and total gamma radioactivity.
Digital image processing techniques were customized to generate images from the airborne geophysical (AGRS & AM) data as well as for enhancing georeference images and integration of the derived information with other data sets.Radioelemental and total magnetic intensity contour maps and images are generated based on corrected and processed data. These images are useful to study the distribution of U, Th and K with respect to ground geology. A composite Ternary image of K-Th-U by assigning R-G-B colours depicts better ground geology and helps in refining geological maps particularly in granitic terrain. The softwares used to generate outputs are Golden Software Surfer, ERDAS Imagine, Ilwis and ENVI.
The outputs are being utilised for atomic minerals exploration, in locating uranium, beach and inland heavy mineral placer deposits, geological mapping and environmental monitoring. Such surveys over Krishna-Godavari, Cauvery and South Rewa Gondwana Basins were taken up, on contract, for the Oil & Natural Gas Corporation in the Exploration of hydrocarbons. Aero-radiometric surveys were also carried out by AMD over Madras Atomic Power Plant (MAPP) at Kalpakkam and Rajasthan Atomic Power Plant (RAPP) at Kota for monitoring the environmental radiation.
AMD has covered an area of about 5.365 lakh sq. km (till March 2004) by high sensitivity AGRS and AM surveys. The contour maps, digital images and processed data are available with AMD headquarters, Hyderabad. AMD dedicates these efforts to those scientists, engineers and pilots, who while exploring new horizons, did not return during 1962 & 1977
A catalogue of AGRS survey data and maps prepared in this regard are available at AMD headquarters, Hyderabad.
The organization has well equipped remote sensing laboratories with opto-mechanical instruments, digital image processing systems, scanners, printers, plotters and expertise in processing, enhancements, Geo-referencing, interpretation and thematic map generation.
The remote sensing data inputs include B&W aerial photographs, hard copies and transparencies of FCC satellite images and digital data of various satellite sensors like IRS-WIFS, LISS-II, LISS-III, PAN, LANDSAT-MSS, TM and SPOT-VHRR.Golden Software Surfer, ERDAS Imagine, ILWIS and ENVI Softwares are used for the image generation and enhancement.All the Regional Headquarters are equipped with remote sensing laboratories.
Spatial database creation of atomic minerals exploration is being carried out for data storage, retrieval, integration, analyses, thematic map generation and target area identification. The spatial database being created includes geological maps, lithostructural maps, AGRS & AM contour maps and images, detailed ground uranium exploration maps, litho-, pedo- and hydro-geochemical maps and enhanced satellite images. The digital maps are stored in ArcView Shape file format along with attribute data. The software used are ESRI ArcGIS Desktop and Workstation, AutoCAD, Golden Software Surfer, ERDAS and ENVI.