Diagram Capture and Electronic Notification with GIMS 1'61

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Diagram Capture and Electronic Notification with
GIMS 1.61

• Nangapuram Venkatesh
• Radiocommunication Bureau

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Introduction to GIMS

• Graphical Interference Management System
• Graphical Reference Database Browser
• View the diagrams stored in REFDB
• Capture of new diagrams
• Gain contours, service area, gain towards
  geostationary orbit
• GXT Manipulation
• Interactive calculations
• Power Flux Density
• Gain Interpolation

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GIMS is Interactive

• One can interact with diagram elements
• Mouse click select an element (contour)
• Cut, copy, paste, delete, apply action
• Mouse double-click show/modify properties
• Gain value, position

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Overall Data Flow
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Create a Diagram
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1
Enter key elements
Select diagram type
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3
Filter
Complex diagrams (map recognition)
Simple diagrams
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Simple Gain Contours Diagrams
Capture a boresight with its coordinates
Define a contour by a constant earth station
elevation angle
Define a contour that has the shape of an ITU
region
A digitized contour limited by an ITU region
A digitized contour limited by an elevation angle
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Simple Service Area Diagrams
Turn an existing gain contour into a service area
Just a location onthe earth
A country or ITU region
A constant earthstation elevationangle
Polygon on the earth
A digitized area limited by an ITU region
A digitized area limited by an elevation angle
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Digitize a Footprint Diagram

• Apply to diagrams in paper form
• Map recognition process
• Select the type of data (gain contour or service
  area information)
• Use the digitizer mouse
• To digitize points by clicking
• To digitize lines by clickn drag
• Filtering

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Digitizer Get It Connected

• Summasketch III, 4-button mousehttp//www.gtcocal
  comp.com/
• Connect to serial port
• GIMS File Digitiser Setup
• Check the connection with map recognition
• Works only under Windows NT/2000

Do NOT install any driver for the tablet
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Map Recognition

• Definition of the mapping of digitizers
  coordinates into earth coordinates.
• Click on at least 6 points of known earth
  coordinates
• Select the projection that has the lowest fit
  value

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Diagram Type Information

• Specifies how digitized lines and points are
  interpreted

Point boresight Line gain contour
Point discrete service point Line service
area limit
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Filtering

• Initially, remove inaccuracies of manual
  digitizing
• Evolved to provide contour correction (useful in
  correcting GXT files)

Select a contour
Reduction Factor Digitized contours often
contains too many points
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GIMS Databases
REFDB
REFDB is Read-Only
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CONTADM

• GIMS databases administrator
• Create/Delete containers
• Add/Remove databases
• View database statistics
• Change database files location
• Manage database access security

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Create a GXT File

• Save first in a database
• Menu File Save or File Save As
• This ensures the diagram is valid.
• Check Confirmation Dialog
• Save As allows to change the satellite
  position.
• Export into a GXT file
• Menu File Gxt Files Export

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GXT Validation ( I )

• To be used when GXT is created manually or
  programmatically
• Ensures diagram is valid
• Validation of syntax
• Validation of content
• Make sure the diagram is correct in the sense
  that gain interpolation will give sensible
  results.
• It is your interest to send us a correct diagram

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GXT Validation ( II )

• Menu File Gxt Files Validate

Select a file to validate
Choose items to validate
Syntax is always validated
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Check Points Visibility

• Category WARNING
• Some points are not visible from the satellite
• No major consequences since they will always be
  ignored (they will not even be displayed).

Check the satellite position
Import/Save/Export in GIMS will discard non
visible points
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Check Open/Closed Contours Layout

• Category WARNING
• Close contours have matching end points
• Open contours should have their end points on the
  horizon
• Critical when end points are really far from the
  horizon
• Can help discovering small holes in contours

Filtering always extends open contours to the
horizon
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Check Loops in ContoursCheck Contours Crossing

• Category FATAL
• Physically not possible
• Gain interpolation would be wrong

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Check for Double Points

• Category FATAL !
• Points too close to each other
• Nothing wrong theoretically but some GIMS
  routines fail to handle such a situation
  correctly.

Select Use Pre-Filtering in validation option
Select Pre-filter the line in the Filter
Options dialog box
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Check for Maximum Distance Between Points ( I )

• Category WARNING and could be FATAL
• Gain interpolation is done in 2D space and
  therefore goes wrong when
• Contours are closed to the horizon
• Contours are closed to each other
• Points are far from each other
• Contours points are linked by line segments.
  This is an approximation which is valid only for
  short distances.

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Check for Maximum Distance Between Points ( II )

• Current limit is strict
• Most of the time there is no problem
• Check the diagram manually
• File Gxt Files Import
• Select gain tool on the toolbar
• Click on map

Filtering can solve the problem. If you do not
want to filter there is an option that makes the
filtering only add points in the contour.
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Check Diagram Size

• Category FATAL
• Too big diagrams will produce unpredictable gain
  values.
• Footprint can have up to about 4000 points.

Use the filtering to reduce the number of points.
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GXT Validation ( III )
File edition
Fast navigation
Validation summary
List of errors warnings
Double-click
Description of selectedmessage
Validate againwith new options
Change validation options
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GIMS 1.61 Setup ( I )

• Developed on Windows 2000
• Limited testing on Windows 9x
• Would recommend Windows 98 SE
• No tests done on Windows Me / NT 4.0
• Digitizer does not work on Windows 9x
• On Windows NT / 2000
• Enough privilege to have write access to registry
  HKEY_LOCAL_MACHINE\Software

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GIMS 1.61 Setup ( II )
GIMS
GIMS ReferenceDatabase
CONTADM
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GIMS Help

• On-line help
• F1 key
• Menu Help Help topics
• Frequently Asked Questions document
• Menu Help FAQ
• http//www.itu.int/brsoft/space/GIMS/index.html
• Olivier.Evrard_at_itu.int