SAASM: Rockwell Collins' next generation GPS receiver design

Rockwell Collins has leveraged its position as a primary military Global Positioning System (GPS) supplier by developing a new, low cost version of the Selective Availability Anti-Spoofing Module (SAASM) for use in multiple applications. The Rockwell Collins SAASM has been designed as a common module that can be used to support all internal SAASM applications. Its architecture provides an advanced set of core functions while at the same time supporting easy integration into various applications. This paper presents the architecture, features, and status of the Rockwell Collins SAASM and describes three applications that incorporate this module, specifically, NavStrike/sup TM/, the small serial interface (SSI) receiver, and GPS Embedded Module (GEM) V/sup TM/. "NavStrike" is a very small, high A/J, high G, fast direct Y (DY), receiver specifically designed for precision guided munitions (PGM) applications. Through the use of a proprietary technique, this receiver provides unclassified GPS measurement data for use in tightly coupled integrations. Position, velocity and time (PVT) outputs are also available. NavStrike uses special features such as a high-speed serial interface, a unique frequency standard and a clock calibration mode to perform fast DY acquisitions after up to 20 years of storage. A SSI product is being developed using the common SAASM module. Among the users of this GPS technology are the ground (low dynamics, minimal environmental) applications that embed the GPS directly within their own equipment. The PVT data provided by the SSI receiver can be easily integrated with the host system providing additional navigation performance with minimal space and cost impact. This SSI module, which uses the new GPS receiver applications module (GRAM) SSI standard, is being designed to be a seamless drop in replacement of existing ground applications embedded receivers. GEM V is the most recent member of the GEM product line. The GEM receivers are designed for high performance, high dynamic embedded applications. GEM V is a SAASM-based module that features the high A/J characteristics and direct Y capabilities of previous GEM products. The GEM V/sup TM/ is integrated with a host system through a dual port RAM or a serial port (RS-422) interface. Once integrated, the GEM can perform as a fully functional guidance system, as a PVT engine, or as a GPS measurement sensor.