Realtime Hierarchical Graphic Display Of Spacecraft Status Mimic 
Diagrams

G.C. Shashidhar

ISRO

Abstract:
Spacecraft mission operations have been conventionally supported by 
health display tools consisting of alphanumeric page formats for many 
years. Tools to generate parameter plots on graphic devices are also 
in use for quite sometime. Even though there have been instances of 
using mimic displays for some missions, this scheme has not made deep 
inroads in the area of mission operations.

This paper discusses a software tool called GDSP developed by ISRO to 
provide hierarchical graphic display of health/status of satellite 
subsystems. The tool has a real potential to replace the conventional 
scheme of alphanumeric displays. In addition to the multipaged 
graphic display of subsystems, it also facilitates the user to 
navigate through the hierarchical structure starting at any level - 
satellite, subsystem, package and proceeding to different levels of 
depths. At each level, the status is depicted in terms of animated 
mimic diagrams. These diagrams consist of static objects for system 
components without any varying attributes and dynamic objects for 
components with attributes associated with health parameters. Dynamic 
objects include analog and digital objects as relevant for the 
components. The attributes are indicated through different colours, 
patterns, icons, barcharts etc. The tool also provides display of 
parameters like temperatures, voltages wherever required.

The tool makes it possible to graphically monitor events like 
thruster firing, relay operations etc during critical manouvres / 
operations.

GDSP provides a user friendly interface for spacecraft controllers 
making it very useful specifically during initial / transfer orbit 
phase and contingency phases.

The tool also includes a graphic editor to define the layout of the 
mimic diagram at any level alongwith the associated linkages to other 
diagrams. This facilitates the tool to be configured with ease for 
any spacecraft.

GDSP has been effectively used for IRS-1C and INSAT-2C mission 
operations. The tool has been implemented on VMS/IGL and UNIX/PHIGS 
environment.

Enhancements on GDSP currently under development include multiple 
window sessions, multimedia features, diagnostic features and event 
based graphic alarms for operator attention.