Testset for Cis-Lunar Communications and Navigation

When people again walk on the moon they will benefit from communications and navigation services that were unimaginable on our first visits. NASA is procuring Lunar Relay Communications Navigation System (LCRNS) as a ‘turnkey’ system. The contractor is responsible for providing a complete system that consists of the Space segment (one or more lunar satellites) and the Ground segment (one or more ground stations). The LunaN et Interoperability Specifcation (LNIS) specifies the interfaces and services that LCRNS provides to the lunar Users. LCRNS provides data and navigation (PNT) services. The data services include real-time frame service, real-time network service and non-real time delay tolerant network (DTN). Both types of data services can be delivered over a relatively low-rate S-band or the high-rate Ka-band links. The S-band link supports data rates from a few kbps to a few Mbps, as well as an ‘emergency’ mode at 15 bps. The Ka-band link supports data rates from 1 to 50 Mbps. LCRNS also provides one-way and two-way ranging, position, and timing using a signal derived from the terrestrial L1C GPS. This signal also carries low-rate broadcast messages (in-phase channel for PNT, quadrature for data). This paper describes a novel, software-centric architecture for a testset that is being developed to verify functionality, compliance, and performance of contractor hardware. The bulk of the testset functionality is made up of ‘golden reference’ modems that are used to verify contractor implementations. It is designed to support up to two simultaneous Users and up to four navigation signal transmitters. The signals and capabilities are expected to change as contractor(s) come on board and requirements are refined. The design of the testset is optimized for many and frequent updates. The proposed architecture takes advantage of the high-speed, multi-core CPU s to move most of the signal processing to the software domain.