TLAM Block III GFS - Software Upgrade of a Premier GPS Weapon

John Nielson, Phil Parker, Tony Smith, Steve Whittlesey

Abstract:	Rockwell Collins has just completed a software upgrade to the GPS flight software (GFS) of the Tomahawk Land Attack Cruise Missile (TLAM) Block III, quite possibly our nation’s premier GPS weapon. Presently the drift of TLAM’s inertial navigation system limits the maximum distance between the final Digital Scene Mapping and Correlation (DSMAC) scene and a target. The GFS software upgrade included the addition of Constellation Freeze Mode (CFM) which freezes the satellite constellation to the optimum set of satellites that will be visible over the CFM period to allow the receiver to maintain a near constant bias after a DSMAC update has been made. This feature allows targets to be further from the final DSMAC scene than is presently possible. The software upgrade also included a modification to allow the receiver to track-through or rapidly recover from pyrotechnic shock levels of thousands of Gs (potentially in a high jamming environment) as occur when the payload doors or the DSMAC camera lens are jettisoned. This change improves TLAM’s ability to attack multiple targets. A number of other smaller modifications were made including enhanced reacquisition after loss of lock due to jamming. The ability to provide performance improvements to an older generation GPS platform represents a significant enhancement in TLAM’s mission capability. This upgrade reflects a significant improvement in the United States’ operational readiness.
Published in:	Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999) September 14 - 17, 1999 Nashville, TN
Pages:	1115 - 1120
Cite this article:	Nielson, John, Parker, Phil, Smith, Tony, Whittlesey, Steve, "TLAM Block III GFS - Software Upgrade of a Premier GPS Weapon," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 1115-1120.
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