Navigation Software Design of the Rockwell International M/V DoD Receiver

Michael P. Taylor, Larry D. Synstelien

Abstract:	This paper is an introduction to the design of the navigation software used within the Phase III Rockwell International Man­pack/Vehicular (M/V) User Equipment. The Collins Government Avionics Division M/V GPS receiver is also known as Receiver Processor Unit !-channel (RPU) with military designation R-2401/U. The paper begins with a review of the overall software design of the M/V User Equipment followed by a description of the navigation software design and sample performance data. The Collins Government Avionics Division GPS software architecture is generally designed for maximum commonality across the entire baseline of one, two and five channel DoD standard receivers. Major receiver equipment differences, such as differences in hardware interfaces, or differences in the number of receiver tracking channels, make it necessary for some tailoring of the GPS software. This paper will emphasize the design of the Receiver Manager and Navigation software functions which are unique to the M/V receiver. The M/V Receiver Manager software controls the selection and acquisition of GPS Satellite Vehicles (SVs) which are tracked on the single receiver channel present within the M/V GPS receiver. After selecting the SV to be tracked, the software must also decide the code, frequency and anti-spoofing status to be used during the satellite acquisition. Code and frequency window search sizes and method of search must also be determined. The method of search depends on various factors including: current internal Receiver Manager conditions; Navigation software estimates of error in position, velocity and time; and estimates of external RF jamming conditions. Receiver Manager software is also responsible for collecting 50 Hz SV down-link data from the satellite tracking (Receiver Processor) software function and passing this information to the Satellite Data Base Manager Software function. GPS pseudo range and delta range measurements are also passed from the Receiver Processor function to the Navigation Software function. The M/V Navigation software function is responsible for maintaining position, velocity and time estimates for the M/V receiver using an eight state Kalman filter. The Kalman filter processes pseudo and delta range measurements from the GPS satellites and can process an auxiliary altitude measurement entered by the operator. In addition to the above duties, the M/V Navigation function also provides estimates of nominal Pseudo Random Noise (PRN) code position, velocity, and acceleration to the Receiver Processor function to aid in satellite acquisition and tracking.
Published in:	Proceedings of the 2nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1989) September 27 - 29, 1989 The Broadmoor Hotel Colorado Spring, CO
Pages:	227 - 233
Cite this article:	Taylor, Michael P., Synstelien, Larry D., "Navigation Software Design of the Rockwell International M/V DoD Receiver," Proceedings of the 2nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1989), Colorado Spring, CO, September 1989, pp. 227-233.
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