International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Spacecraft communication simulators are extremely useful for integration and testing of spacecraft control centers and supporting ground systems. To reduce development costs, a Windows NT PC-based simulation system is being developed to support testing for upcoming NASA missions. The spacecraft simulation suite of tools integrates modules within a core infrastructure and is customized to meet mission unique specifications not met by the baseline system.