As described in “JWST Integrated Simulation and Test (JIST) Core” (GSC-16739-1) on page 25, the JIST system is a software-based simulator that uses the James Webb Space Telescope (JWST) operational ground system, ground system command/telemetry databases, simulated flight computers, and unmodified flight software binaries to provide dynamic analysis capabilities. There is no hardware in the loop; the flight software communicates over a simulated MIL-STD-1553 and Spacewire port. The JIST SSR Simulator is a reusable component of the JIST system, and is responsible for simulating basic SSR functionality.
In order to develop a software-only test environment for the JWST mission, a solution was needed to simulate the behaviors of the JWST SSR. The as-is solution requires the utilization of an Excalibur 1002 Single Board Computer running custom software to simulate SSR functions and interfaces to the JWST Command and Telemetry Processor (CTP).
The JIST SSR Simulator is a component of the JIST system and is responsible for simulating basic SSR functionality. The primary purpose of the SSR Simulator is to assist in performing independent verification and validation (IV&V) of the flight software. The SSR simulator is a software-only simulator that provides the necessary interface to the JWST flight software and typically simulates SSR management functions. Specific functions include playback, record, and telemetry transmission. The SSR simulator is also equipped with many different configurations that can be initialized using command line arguments.
The JIST SSR simulator is software-only and eliminates the need to acquire and maintain various hardware equivalent configurations. The simulator provides additional functionality and configurations to support specific independent testing objectives.
This work was done by Scott Zemerick of Goddard Space Flight Center. GSC-16741-1