Today's Editorial - 08 November 2020
Agreement for geo-spatial co-operation
Source: By Milind Kulshreshtha: The Financial Express
The Indo-US Basic Exchange and Cooperation Agreement for Geo-Spatial Cooperation (BECA) pertains to exchange of Geospatial Intelligence (GEOINT) information for use by the governments for defence and other purposes. It defines the use and analysis of imagery and geospatial information to describe geographically referenced activities on the earth. It identifies the geographic location and characteristics of natural or man-made features on Earth, and includes the statistical data, sensing data, mapping and Survey data so as to create processed data like mapping, charting, geodetic data and related information.
Military Context of GEOINT
Geo-data referencing framework and Timing accuracy (via an Atomic clock) are essential for Real-time computation of Air, Surface and Sub-surface warfare functions to achieve a successful missile impact. The complexity in precise Geo-tagging of a target begins with the Geo-reference plane problem caused due to Earth’s shape being spheroid (or ellipsoid) and various other factors like Geo-corrections emanating from varying gravitational profiles etc. Obtaining a precise and accurate location of a digital target track for warfare algorithms and mathematical computations to work is likely to be highly error-prone in case Geo referencing the framework is not well defined or regularly updated.
A track reported by radars and a plethora of other sensors (sonars, EW sensors etc.) fitted on a geographically disperse static or dynamic platform makes this solution all the more inaccurate for a perfect weapon launch. Further, any lack of Real ‘timeliness’ of the signal information on the target can add to calculations being run on a ‘stale’ track, i.e. a weapon launch at a position where a target may have never existed or likely to be in the future. The weapons are launched at a future position for a dynamic target and in today’s Netcentric Warfare which is highly dependent on a Multi-platform Multi-sensor data Fusion (MPMSDF) engine, such errors can lead to serious consequences since the fast-moving hostile fighter jets or incoming missiles may not give a second opportunity to intercept them. This is a cause of concern against a technologically advanced adversary like China.
Geo Reference Systems
Geo Reference systems define constants, conventions, models and parameters, which serve as the necessary basis for the mathematical representation of geometric and physical quantities on Earth realized in terms of geometric coordinates. Here, the geodetic datum fixes unambiguously the relationship between a ‘Reference frame’ to a ‘Reference system’ by allocating a set of parameters like coordinates of the origin of the system (X0, Y0, Z0) along with the directions of coordinate axes, and specifies a scale like a unit of length (e.g. km) etc. Geodesy concepts of measurements are corrected for three fundamental properties of the Earth viz. Earth’s geometric shape, gravitational field variations, Earth’s orientation in space, along with discrepancies in these properties caused by varying time dimensions. From the military point of view, the position of any place, object or point can be represented by means of its geographical coordinates expressed in terms of three-dimensional form viz. Latitude, Longitude and height. Here, the Latitude and Longitude are measured from the intersection of lines of Prime Meridian (passing through Greenwich) and the Equator. Similarly, the height (or elevation) is normally measured from the Mean Sea Level (MSL). Satellites are used for these measurements, corrections and better accuracy.
Global Navigation Satellite System (GNSS) is the constellation of satellites sending signals from Space to GNSS Receivers, ideally providing global coverage. This signal information pertains to positioning and timing data, which is utilised by the Receivers to determine their location. GNSS includes US Navstar Global Positioning System (GPS), Europe’s Galileo, Russia’s Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS) and China’s Beidou Navigation Satellite System.
The interoperability for multiple GNSS systems is achieved through a consistent reference coordinate system and time system. The GNSS performance is enhanced by the use of Regional Satellite-based Augmentation Systems (SBAS) e.g. EGNOS (European Geo Stationary Navigation Overlay Service), which improves GPS accuracy and reliability. India too shall have a similar capability when ISRO’s PNT (Position, Navigation and Time) services are available using Indian satellite constellations as part of NavIC system.
Combat Track Data Fusion
The radar ‘plots’ are created at the signal processing level and, in turn, generate the radar tracks. Every new track is held in the category of a tentative track and called as ‘confirmed’ track after subsequent plot updates are obtained, but unfortunately, the time delays start from here. At a Theatre Command level, multiple tracks from varied sources are fused to achieve a Common Operational Picture (COP) for optimal exploitation of resources. During Track fusion, two Real-time tracks with similar type and identity are fused centrally using a strict military algorithm, which no nation ever reveals. However, fusion accuracy is highly dependent on the Geo-reference errors of the reporting units or co-ordinate conversion inaccuracies, along with Time synchronization errors.
A datum is a base referred to which a ‘position’ is defined. India uses Everest Datum (named on first Surveyor General of India, Sir George Everest) where a mathematical spheroid roughly representing the shape of Indian sub-continent is used for all measurements.
In 1984, WGS 84 (World Geodetic Survey 1984) coordinate System was adopted universally as the standard form of Geographical Coordinates Representation System. All the century-long effort in collating the maps, records and data available in the form of Everest Datum was thus transformed into WGS84. But, error crept in when transforming the geographical coordinates from one system to other even when using various software modules.
In recent times, as per National Map Policy 2005, Survey of India is entrusted with the responsibility of producing, maintaining and disseminating topographic map database of the whole country. In order to make this information available smoothly across all organisations, India’s National Data Sharing and Accessibility policy 2012 exists, however, MoD is exempted from this policy. Army’s Military Survey organization is the custodian of Defence GIS (Geographic Information System) and supplies maps to the Defence Forces and, to MHA for Police work. A tri-services organization for handling satellite imagery exists as part of the Defence Space Agency. For nautical charts, Indian Navy has its own National Hydrographic Office (NHO) at Dehradun, which publishes Naval Charts under the aegis of International Hydrographic Organisation (IHO) for use by all sea-going vessels. The sea charts are regularly updated and printed in Digital form and all updates and current information transmitted as a broadcast regularly to ships at sea.
US Spatial Coordinate System
Presently US uses NAD 83 (North American Datum of 1983) and NAVD 88 (North American Vertical Datum) standards. However, US Surveys are continuously undertaken for data collection for greater data accuracy. The US plans to define a new Datum by 2022 to improve alignment with reference frames and improve accuracy of GPS-derived heights also. NAVD 88 too is planned to be replaced and collection of airborne gravity data to help improve future geoid models is in progress.
US Military uses Continuously Operating Reference Stations (CORS) to provide accurate coordinates to its Defence Forces. GPS/GNSS is used in the national spatial reference system for computing high-accuracy GPS orbits. The Airborne and terrestrial survey information, gravity data, and gravity-based geoids or datums are continuously collected for updates in a time-critical manner. Also, Geoid Slope Validation Surveys (GSVS) are conducted to test gravimetric geoid model accuracy for the next vertical Datum. The US has an active International Earth Rotation and Reference System Service (IERS) survey program in place for Geo measurement improvements.
BECA Agreement defines the Geospatial-intelligence information which emanates from GEOINT information collection or transformation. It comprises of geodetic, geomagnetic, topographic, hydrographic, cartographical, bathymetric and similar essential information data packets. The items include maps, nautical and aeronautical charts; geospatial information and data like geodetic, geophysical, geomagnetic and gravity data.
Under BECA, the US shall exchange technical and procedural information related to the standardization of methods, specifications and formats for the collection, processing and production of GEOINT information with India. This shall also include the Tools and Models to process GPS data and Transform Latitude, Longitude and Height coordinates across various Reference frames. Along with the GPS derived heights, an accurate geoid model will help determine the direction of water flows. The GNSS antenna calibration for the Antenna Reference Point (ARP) and North Reference Point (NRP) shall be part of the GEOINT for better Reference data.
In this Indo-US Agreement, initially the Geographical range of GEOINT information and data exchanged shall be limited to the Indian sub-continent and contiguous bordering regions. However, there is a likelihood of a clause where this term may be modified (as mutually agreed) when India requests for Defence, humanitarian assistance or disaster management assistance, where the US may expand the geographical range for GEOINT information exchange well beyond the Indian borders.