Flight software verification methods in Frontier Radio for solar probe plus mission

Success of deep space missions requires comprehensive performance verification for all hardware and software systems on the spacecraft over a broad scope of conditions and configurations, including the telecommunications subsystem. NASA Solar Probe Plus mission uses a software-defined radio for its telecommunications; thus a dedicated suite of tests are required for verification of the radio software in addition to traditional hardware verification procedures. Frontier Radio, developed by Johns Hopkins University Applied Physics Laboratory with near-Earth mission flight heritage, uses its software as a means to enhance its digital signal processing capabilities with no loss of robustness; thus, the testing required to validate its features is commensurately more complex. For this reason, a suite of tests were developed to interface with the radio software via a proprietary PC-based software platform to exercise the full scope of radio software functionality through a methodical and repeatable process. Automated logging functions embedded in the tests ensured that tests were documented with minimal operator intervention for greater accuracy and consistency than manual procedures used for hardware-only radios. Similarly, software-based interfaces to ground station equipment were developed to minimize the probability of operator error when testing the radio under varying signal conditions simulated by external instruments. The testing process identified several issues with radio software whose discovery would have been unlikely without the strenuous operating conditions created by the test procedure; the issues were subsequently mitigated resulting in a later software upgrade. Repeatability, and consequently the reduction of testing costs, was demonstrated through the execution of regression testing when the upgraded radio software was released. Results of the tests were examined and verified both internally and by external resources, namely NASA Independent Verification & Validation (IV&V), and the test procedures and results have been documented to the extent required for its reuse with future adaptations of Frontier Radio for other space mission applications. Additional software testing was performed that verified radio receiver functionality to a greater depth and complexity than that defined by formal requirements; the results were nominal as determined by the process of internal documentation and review.