STK/GIS --The Unique Analytical Link Between ArcView GIS Information and
Space/Air-Based Assets Modeled in Satellite Tool Kit (STK)

Author: Travis Langster (travis@stk.com)
Organization: Analytical Graphics, Inc (http://www.stk.com)
 
 

STK/GIS--The Unique Analytical Link Between ArcView GIS Information and
Space/Air-Based Assets Modeled in Satellite Tool Kit (STK)

ABSTRACT

Satellite Tool Kit/Geographic Information System (STK/GIS) provides the interface between Esri's industry-leading ArcView® GIS and the powerful analytical capabilities of STK. The STK/GIS extension broadens the analytical capabilities of both STK and ArcView GIS by interfacing STK sensor footprints and swaths, antenna gain contours, coverage regions, ground areas, and facility sites with detailed GIS databases. ArcView® GIS is able to use sensor and antenna coverage information for bounding information queries, while STK can utilize the query-based data in coverage analysis for remote sensing and communications applications. Unique solutions made possible by this interface will be presented in the areas of defense, search and rescue, telecommunications coverage, and image acquisition.

The STK/GIS package utilizes the bi-directional data exchange capabilities with ArcView. This information and data sharing links the power of Esri's ArcView® software and databases with the aerospace systems analysis and visualization tools of STK. This paper will examine several uses and applications for the STK/GIS interaction with ArcView and provide relevant examples of these applications. Inherent space systems analysis capabilities within STK will be reviewed along the way.

STK/GIS Background and Description

Satellite Tool Kit/Geographic Information System (STK/GIS) provides the ability to perform a complex geographic and demographic analyses within space-to-Earth geometries, such as satellite to ground area targets, satellite fields of regard and swaths, and coverage regions of interest. The STK/GIS bundle can assist the user in optimally selecting ground stations, gateways, or remotely located satellite tracking stations based on an unlimited number of complex demographic, environmental and other geographically-referenced information. As a powerful analysis tool, it can analyze the effectiveness of a satellite system or the demographics of a supporting ground network by referencing STK objects against numerous GIS detailed information databases.

STK/GIS Applications

Users are able to produce GIS-industry standard "shapefiles" through detailed GIS analyses, then import the shapefiles into STK to optimally create STK facilities, satellite footprints and swaths, area targets, constellations and coverage regions. Similarly, users can take the following STK data sets:

and export this data as shapefiles to perform informative GIS analyses within ArcView®. STK/GIS works with STK or STK Professional for more complex analysis requirements. STK/GIS with STK/Coverage is design and analysis tool. In a design environment, a satellite television provider may wish to create a geostationary satellite sensor footprint and position it so it covers the maximum number of middle-income households possible. Using the STK/GIS bundle with a STK/Coverage and a GIS income database, the user can converge upon an optimal design.

As an analysis tool, a current satellite operator may use the STK/GIS bundle to analyze what geographical and demographical environments their satellite passes over each day, such as people, automobiles, homes, cellular areas, zip codes, televisions, fast food restaurants, in order to maximize their assets and revenues.

Military analyst could make use of STK's visibility calculations to a region or deck of ground based targets from space assets. This analysis could be perfected by GIS queries within ArcView that differentiate between SAM sites, airfields, base camps, or emitter locations. Space surveillance users may assess potential pokethrough locations or define antenna locations for interference calculations with STK/Communications module. The linked image shows a calculation with STK/Comm to determine the power levels (25db) from a geostationary satellite covering South America. The STK/GIS functionality with ArcView® allows the user to determine the cities over 200K in population that fall within the specified gain contours. The application to a specific problem becomes more relevant as the appropriate database within ArcView® is utilized.

Sample STK/GIS Data Results with ArcView

Commercial Satellite Communications
The typical analysis and visualization results that can be produced with STK/GIS and ArcView® will be examined. The first example will provide results of a satellite based commercial communications system. This scenario application computes the potential impact of sun radio frequency interference (RFI) in a GEO communications downlink around the time of the autumnal equinox. In this case a geostationary communications satellite is orbiting at -80 degrees west longitude and is tasked to provide television coverage to South America. The spacecraft is configured with a transmitter (40Mbps data rate and BPSK modulation) using the ITU GIMROC antenna pattern file, Gimroc4-30dbgain. The ground facility, manaus, is configured with a parabolic receive antenna. The ground receiver models the location TV station's satellite dish. The TV system requires a certain link closure quality for the best TV reception. This is equivalent to a maximum bit error rate (BER) constraint of 1x10e-9. STK/Coverage is used to evaluate the ability of the satellite to cover the defined service area.

Calculations utilizing STK/Comm determine that the system loses link closure (BER constraint exceeded) around 17:23:15 during the calculation time period. Further analysis of the sun noise temperature also shows the effect the sun has on the system's performance. Dynamic coverage analysis using STK/Coverage reveals the of Received Isotropic Power (RIP) contour levels for the service area of interest. The hole in the contour level dynamically indicates where the reception would be most affected because of the Sun RFI.

Utilizing STK/GIS export capability, a shape file is generate for performing queries on the data sets within ArcView. Once a theme is created STK/GIS extension is used to analyze the contour shape representing the 25dbi antenna gain. The query performed produces a new theme that highlights the World Cities that intersect the 25dbi contour and has a population greater than 200K. This represents higher density population areas and identifies locations that a TV station may need to make alternative communication links within this service area.

Space Based Remote Sensing

The importance and growing market of space based remotes sensing requires that these resources are used efficiently and intelligently to maximize benefits to customers and owner/operators of these systems. Visibility calculations in STK/Professional provide the owner/operators the ability to perform mission planning and operational tasking of these systems. Imaging systems capabilities to collect ground point and area targets of interest can be vary based on many constraints. A few of these constraints that are considered in STK/Professional include:

The objective of the scenario is to determine when and where stereo imaging exist by the active LANDSAT and SPOT satellites. The orbital elements for each satellite were obtained from the STK satellite database included with the standard version of STK. The database may be updated regularly either through the Satellite Database Tool or by going directly to the AGI website (http://www.stk.com). For this application a 20 degree minimum elevation angle constraint and direct sun lighting constraint over the global coverage was implemented. STK/Coverage with a N Asset Figure Of Merit (FOM) set to at least 2 is used to determine the occasions when the global area will have access to at least 2 satellites. The results can be seen visually (2D map), as a report or as a graph. This graphic view represents the instantaneous stereo opportunities on the 2-D display. Notice that opportunities are only available on the lit side of the solar terminator. Utilizing STK/GIS to export the sensor swaths (for Landsat7 and Spot2) that represent 20 degree minimum elevation angle, shapefiles are generated and added as a theme in ArcView. The overlapping stereo imaging shapefile and the world cities that are contained within are represented in the Stereo Cities theme. Essentially we have a target deck of potential world cities that stereo images could be obtained. This target deck can be further analyzed by Importing into STK with STK/GIS extension. The resulting displays in 2D and STK/VO show the overlapping stereo coverages for the 2 remote sensing satellites and the target deck determined within ArcView.

The remote sensing application is quite often analogous to Space Intelligence, Surveillance, and Reconnaissance (ISR) missions. Depending on the capabilities of the systems and the collection requirements, Space ISR missions utilize similar constraints. The STK/Chain capabilities allow ISR collection managers to plan, predict, and task collection systems based on maximized collection opportunities against a target deck.

Ground To Space Based Signal Interception/Interference
Space-based receivers can detect signal emissions from ground antennas. These transmissions, although not desired, can be intercepted for intelligence or competitive advantages. This can occur from a ground antenna that is located at high latitudes and directs a transmission that is low in the horizon. This example animation provides a sample case of what is sometimes known as a pokethrough. During an unexpected intercept a geostationary satellite with a beam that is off boresight happens to be tuned to the frequency of a ground antenna. After a query from a known emitter database from within ArcView, an STK/GIS user can import these targets into STK to perform coverage and link analysis. The link analysis can provide a detailed dynamic link budget report that defines the gains and losses of the signal interception or interference.

ArcView Extensions and STK/GIS
Several scripts and extensions developed by users allow more automated functionality between ArcView and STK/GIS. Functionality of these scripts include:

The complimentary features and expandable capabilities and automation complete a package that provides satellite systems analysis for complex geometries and payload parameters and the ability to perform GIS queries and analyses against these systems. Visualization of both types of data deliver extremely invaluable ways to understand and present the results.

The power of the ArcView and STK/GIS relationship will continue to grow across market segments as more commercial and government systems become dependent on space based information systems and technology. These systems are designed and operated on how well they meet criteria such as:


Accurate space system modeling and GIS data sets provide the tools for assessing the characteristics of design, modeling, operating, and visualizing the above mentioned criteria. The STK/GIS package provides the path to share and manipulate data within the GIS environment.

Acknowledgements
James Koppersmith
Product Manager and Business Partner Lead
Analytical Graphics, Inc.
Jkoppersmith@stk.com